Re: Dynamically change enumeration list of DRM enumeration property
On Wed, 03 Jun 2020 20:20:44 + (UTC) Jonas Karlman wrote: > Hi, > > On 2020-06-03 11:12, Pekka Paalanen wrote: > > On Wed, 3 Jun 2020 10:50:28 +0530 > > Yogish Kulkarni wrote: > > ... > >> The primary reason for why content producer masters video/gfx content as > >> limited range is for compatibility with sinks which only support limited > >> range, and not because video decoders are not capable of decoding > >> full-range content. > > > > What I was asking is, even if the video content is limited range, why > > would one not decode it into full-range pixels always and if the sink > > need limited range, then convert again in hardware? When done right, it > > makes no difference in output compared to using limited range > > through-out if both content and sink use limited range. > > For the Allwinner/Amlogic/Rockchip arm devices I mainly play with the > video decoder does not support range conversion (to my knowledge) and will > produce NV12/YU12 framebuffers in the range the video was encoded in. > > These devices typically lack a high-performance GPU/3D-accelerator > and may have limited CSC capabilities in the display controller. > The HDMI block can usually do simple RGB/YUV and full/limited conversions, > but using these conversions typically produce banding effects. > > Being able to passthrough decoded framebuffers in the entire pipeline from > decoder, display controller and hdmi block typically produce best results. This is very helpful. It means I really do need to take range into account in Wayland protocol and make sure it can be communicated. Thanks, pq pgpepNdQ3HDtN.pgp Description: OpenPGP digital signature ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Dynamically change enumeration list of DRM enumeration property
Hi, On 2020-06-03 11:12, Pekka Paalanen wrote: > On Wed, 3 Jun 2020 10:50:28 +0530 > Yogish Kulkarni wrote: > >> Inline.. >> >> On Mon, Jun 1, 2020 at 2:19 PM Pekka Paalanen wrote: >> >>> On Mon, 1 Jun 2020 09:22:27 +0530 >>> Yogish Kulkarni wrote: >>> Hi, For letting DRM clients to select output encoding: Sink can support certain display timings with high output bit-depths >>> using multiple output encodings, e.g. sink can support a particular timing with RGB 10-bit, YCbCr422 10-bit and YCbCr420 10-bit. So DRM client may want >>> to select YCbCr422 10-bit over RBG 10-bit output to reduce the link >>> bandwidth (and in turn reduce power/voltage). If DRM driver automatically selects output encoding then we are restricting DRM clients from making >>> appropriate choice. >>> >>> Hi, >>> >>> right, that seems to be another reason. >>> For selectable output color range: Certain applications (typically graphics) usually rendered in full range while some applications (typically video) have limited range content. >>> Since content can change dynamically, DRM driver does not have enough >>> information to choose correct quantization. Only DRM client can correctly select >>> which quantization to set (to preserve artist's intent). >>> >>> Now this is an interesting topic for me. As far as I know, there is no >>> window system protocol to tell the display server whether the >>> application provided content is using full or limited range. This means >>> that the display server cannot tell DRM about full vs. limited range >>> either. It also means that when not fullscreen, the display server >>> cannot show the limited range video content correctly, because it would >>> have to be converted to full-range (or vice versa). >>> >> Right, but there could be DRM client which doesn't use window system (e.g. >> Gstreamer video sink) and wants to select between full/limited color range. >> I agree that there is no window system protocol yet but maybe Wayland >> protocol could be added/extended for this purpose once we finalize things >> that needs to be done in DRM. > > Hi, > > right. If you have that use case and a userspace project welcomes such > feature, you're good. Kodi is a userspace application that is very interested in being able to control or set preferred HDMI output format (rgb444/yuv444/422/420) and quantization range (full/limited). Main reason is to allow end-users to make overrides when sink EDID don't fully match the TV/AVR features or when drm driver makes a bad automatic choice. Hans Verkuil's conclusion in HDMI RGB Quantization Range Lessons at [1] hold ture, it is total chaos. Right now, Kodi set the COLOR_ENCODING and COLOR_RANGE plane properties to let kernel know color encoding and color range of a YUV framebuffer. A single active plane showing a YUV framebuffer with limited range could hint a drm driver that end-user might want to use YUV and limited range output to prevent any banding effect when watching a movie. But in the case of when there is a second overlay plane for OSD or subtitles it may become very hard to guess what configuration works best for end-user. I have piggybacked on the "content type" connector property in [2] for my personal use to signal my drm driver if YUV (Movie) or RGB (Graphics) output is preferred this far but proper drm properties would really help :-) [1] https://elinux.org/images/5/53/Elce2017_0-hdmi.pdf [2] https://github.com/xbmc/xbmc/pull/14358 > > If you propose a KMS property for this, I would hope the patches > document or have links pointing to answers to all my questions here. > That would help both driver and userspace implementations to get into > the same mindset. > >>> But why would an application produce limited range pixels anyway? Is it >>> common that hardware video decoders are unable to produce full-range >>> pixels? >>> >> >> The primary reason for why content producer masters video/gfx content as >> limited range is for compatibility with sinks which only support limited >> range, and not because video decoders are not capable of decoding >> full-range content. > > What I was asking is, even if the video content is limited range, why > would one not decode it into full-range pixels always and if the sink > need limited range, then convert again in hardware? When done right, it > makes no difference in output compared to using limited range > through-out if both content and sink use limited range. For the Allwinner/Amlogic/Rockchip arm devices I mainly play with the video decoder does not support range conversion (to my knowledge) and will produce NV12/YU12 framebuffers in the range the video was encoded in. These devices typically lack a high-performance GPU/3D-accelerator and may have limited CSC capabilities in the display controller. The HDMI block can usually do simple RGB/YUV and full/limited conversions,
Re: Dynamically change enumeration list of DRM enumeration property
Hi all, On Wed, 3 Jun 2020 at 10:57, Ville Syrjälä wrote: > > On Wed, Jun 03, 2020 at 12:12:23PM +0300, Pekka Paalanen wrote: > > On Wed, 3 Jun 2020 10:50:28 +0530 > > Yogish Kulkarni wrote: > > > > > Inline.. > > > > > > On Mon, Jun 1, 2020 at 2:19 PM Pekka Paalanen wrote: > > > > > > > On Mon, 1 Jun 2020 09:22:27 +0530 > > > > Yogish Kulkarni wrote: > > > > > > > > > Hi, > > > > > > > > > > For letting DRM clients to select output encoding: > > > > > Sink can support certain display timings with high output bit-depths > > > > using > > > > > multiple output encodings, e.g. sink can support a particular timing > > > > > with > > > > > RGB 10-bit, YCbCr422 10-bit and YCbCr420 10-bit. So DRM client may > > > > > want > > > > to > > > > > select YCbCr422 10-bit over RBG 10-bit output to reduce the link > > > > bandwidth > > > > > (and in turn reduce power/voltage). If DRM driver automatically > > > > > selects > > > > > output encoding then we are restricting DRM clients from making > > > > appropriate > > > > > choice. > > > > > > > > Hi, > > > > > > > > right, that seems to be another reason. > > > > > > > > > For selectable output color range: > > > > > Certain applications (typically graphics) usually rendered in full > > > > > range > > > > > while some applications (typically video) have limited range content. > > > > Since > > > > > content can change dynamically, DRM driver does not have enough > > > > information > > > > > to choose correct quantization. Only DRM client can correctly select > > > > which > > > > > quantization to set (to preserve artist's intent). > > > > > > > > Now this is an interesting topic for me. As far as I know, there is no > > > > window system protocol to tell the display server whether the > > > > application provided content is using full or limited range. This means > > > > that the display server cannot tell DRM about full vs. limited range > > > > either. It also means that when not fullscreen, the display server > > > > cannot show the limited range video content correctly, because it would > > > > have to be converted to full-range (or vice versa). > > > > > > > Right, but there could be DRM client which doesn't use window system (e.g. > > > Gstreamer video sink) and wants to select between full/limited color > > > range. > > > I agree that there is no window system protocol yet but maybe Wayland > > > protocol could be added/extended for this purpose once we finalize things > > > that needs to be done in DRM. > > > > Hi, > > > > right. If you have that use case and a userspace project welcomes such > > feature, you're good. > > > > If you propose a KMS property for this, I would hope the patches > > document or have links pointing to answers to all my questions here. > > That would help both driver and userspace implementations to get into > > the same mindset. > > > > > > But why would an application produce limited range pixels anyway? Is it > > > > common that hardware video decoders are unable to produce full-range > > > > pixels? > > > > > > > > > > The primary reason for why content producer masters video/gfx content as > > > limited range is for compatibility with sinks which only support limited > > > range, and not because video decoders are not capable of decoding > > > full-range content. > > > > What I was asking is, even if the video content is limited range, why > > would one not decode it into full-range pixels always and if the sink > > need limited range, then convert again in hardware? When done right, it > > makes no difference in output compared to using limited range > > through-out if both content and sink use limited range. > > > > > Also, certain cinema-related content (e.g., movies) may > > > be better suited for limited range encoding due to the level of detail > > > that > > > they need to present/hide (see "Why does limited RGB even exist?" section > > > in > > > https://www.benq.com/en-us/knowledge-center/knowledge/full-rgb-vs-limited-rgb-is-there-a-difference.html#:~:text=Full%20RGB%20means%20the%20ability,less%20dark)%20than%20full%20RGB > > > ). > > > > That is a very nice link, thanks! > > > > But to me it seems the section "Why is this a problem?" gets "crushed > > blacks" backwards, so maybe I just don't get it. > > > > I would assume that if the source (computer) sends full-range pixel > > values on the wire and the sink (monitor) works in limited-range mode, > > then you would get crushed blacks and crushed whites. > > > > But if the source sends limited-range data and the sink works in > > full-range more, you'd get the "washed out" image. > > > > My thinking comes from the mapping of channel values: if 0-16 and > > 235-255 ranges show no difference within them, I'd call that "crushed". > > Similarly if one assumes 16 is darkest black and it's actually not, > > you'd get "washed out" (I might call it compressed instead, because it > > affects both black and white ends, unable to achieve both the darkest > > black
Re: Dynamically change enumeration list of DRM enumeration property
On Wed, Jun 03, 2020 at 12:12:23PM +0300, Pekka Paalanen wrote: > On Wed, 3 Jun 2020 10:50:28 +0530 > Yogish Kulkarni wrote: > > > Inline.. > > > > On Mon, Jun 1, 2020 at 2:19 PM Pekka Paalanen wrote: > > > > > On Mon, 1 Jun 2020 09:22:27 +0530 > > > Yogish Kulkarni wrote: > > > > > > > Hi, > > > > > > > > For letting DRM clients to select output encoding: > > > > Sink can support certain display timings with high output bit-depths > > > using > > > > multiple output encodings, e.g. sink can support a particular timing > > > > with > > > > RGB 10-bit, YCbCr422 10-bit and YCbCr420 10-bit. So DRM client may want > > > > > > > to > > > > select YCbCr422 10-bit over RBG 10-bit output to reduce the link > > > bandwidth > > > > (and in turn reduce power/voltage). If DRM driver automatically selects > > > > output encoding then we are restricting DRM clients from making > > > appropriate > > > > choice. > > > > > > Hi, > > > > > > right, that seems to be another reason. > > > > > > > For selectable output color range: > > > > Certain applications (typically graphics) usually rendered in full range > > > > while some applications (typically video) have limited range content. > > > Since > > > > content can change dynamically, DRM driver does not have enough > > > information > > > > to choose correct quantization. Only DRM client can correctly select > > > which > > > > quantization to set (to preserve artist's intent). > > > > > > Now this is an interesting topic for me. As far as I know, there is no > > > window system protocol to tell the display server whether the > > > application provided content is using full or limited range. This means > > > that the display server cannot tell DRM about full vs. limited range > > > either. It also means that when not fullscreen, the display server > > > cannot show the limited range video content correctly, because it would > > > have to be converted to full-range (or vice versa). > > > > > Right, but there could be DRM client which doesn't use window system (e.g. > > Gstreamer video sink) and wants to select between full/limited color range. > > I agree that there is no window system protocol yet but maybe Wayland > > protocol could be added/extended for this purpose once we finalize things > > that needs to be done in DRM. > > Hi, > > right. If you have that use case and a userspace project welcomes such > feature, you're good. > > If you propose a KMS property for this, I would hope the patches > document or have links pointing to answers to all my questions here. > That would help both driver and userspace implementations to get into > the same mindset. > > > > But why would an application produce limited range pixels anyway? Is it > > > common that hardware video decoders are unable to produce full-range > > > pixels? > > > > > > > The primary reason for why content producer masters video/gfx content as > > limited range is for compatibility with sinks which only support limited > > range, and not because video decoders are not capable of decoding > > full-range content. > > What I was asking is, even if the video content is limited range, why > would one not decode it into full-range pixels always and if the sink > need limited range, then convert again in hardware? When done right, it > makes no difference in output compared to using limited range > through-out if both content and sink use limited range. > > > Also, certain cinema-related content (e.g., movies) may > > be better suited for limited range encoding due to the level of detail that > > they need to present/hide (see "Why does limited RGB even exist?" section > > in > > https://www.benq.com/en-us/knowledge-center/knowledge/full-rgb-vs-limited-rgb-is-there-a-difference.html#:~:text=Full%20RGB%20means%20the%20ability,less%20dark)%20than%20full%20RGB > > ). > > That is a very nice link, thanks! > > But to me it seems the section "Why is this a problem?" gets "crushed > blacks" backwards, so maybe I just don't get it. > > I would assume that if the source (computer) sends full-range pixel > values on the wire and the sink (monitor) works in limited-range mode, > then you would get crushed blacks and crushed whites. > > But if the source sends limited-range data and the sink works in > full-range more, you'd get the "washed out" image. > > My thinking comes from the mapping of channel values: if 0-16 and > 235-255 ranges show no difference within them, I'd call that "crushed". > Similarly if one assumes 16 is darkest black and it's actually not, > you'd get "washed out" (I might call it compressed instead, because it > affects both black and white ends, unable to achieve both the darkest > black and the brightest white). > > Anyway, I believe I do understand that if you have content in one > range and the sink assumes a different range, the content will show > poorly. I don't doubt that. > > My question instead is: why would it be bad to always
Re: Dynamically change enumeration list of DRM enumeration property
On Wed, 3 Jun 2020 10:50:28 +0530 Yogish Kulkarni wrote: > Inline.. > > On Mon, Jun 1, 2020 at 2:19 PM Pekka Paalanen wrote: > > > On Mon, 1 Jun 2020 09:22:27 +0530 > > Yogish Kulkarni wrote: > > > > > Hi, > > > > > > For letting DRM clients to select output encoding: > > > Sink can support certain display timings with high output bit-depths > > using > > > multiple output encodings, e.g. sink can support a particular timing with > > > RGB 10-bit, YCbCr422 10-bit and YCbCr420 10-bit. So DRM client may want > > to > > > select YCbCr422 10-bit over RBG 10-bit output to reduce the link > > bandwidth > > > (and in turn reduce power/voltage). If DRM driver automatically selects > > > output encoding then we are restricting DRM clients from making > > appropriate > > > choice. > > > > Hi, > > > > right, that seems to be another reason. > > > > > For selectable output color range: > > > Certain applications (typically graphics) usually rendered in full range > > > while some applications (typically video) have limited range content. > > Since > > > content can change dynamically, DRM driver does not have enough > > information > > > to choose correct quantization. Only DRM client can correctly select > > which > > > quantization to set (to preserve artist's intent). > > > > Now this is an interesting topic for me. As far as I know, there is no > > window system protocol to tell the display server whether the > > application provided content is using full or limited range. This means > > that the display server cannot tell DRM about full vs. limited range > > either. It also means that when not fullscreen, the display server > > cannot show the limited range video content correctly, because it would > > have to be converted to full-range (or vice versa). > > > Right, but there could be DRM client which doesn't use window system (e.g. > Gstreamer video sink) and wants to select between full/limited color range. > I agree that there is no window system protocol yet but maybe Wayland > protocol could be added/extended for this purpose once we finalize things > that needs to be done in DRM. Hi, right. If you have that use case and a userspace project welcomes such feature, you're good. If you propose a KMS property for this, I would hope the patches document or have links pointing to answers to all my questions here. That would help both driver and userspace implementations to get into the same mindset. > > But why would an application produce limited range pixels anyway? Is it > > common that hardware video decoders are unable to produce full-range > > pixels? > > > > The primary reason for why content producer masters video/gfx content as > limited range is for compatibility with sinks which only support limited > range, and not because video decoders are not capable of decoding > full-range content. What I was asking is, even if the video content is limited range, why would one not decode it into full-range pixels always and if the sink need limited range, then convert again in hardware? When done right, it makes no difference in output compared to using limited range through-out if both content and sink use limited range. > Also, certain cinema-related content (e.g., movies) may > be better suited for limited range encoding due to the level of detail that > they need to present/hide (see "Why does limited RGB even exist?" section > in > https://www.benq.com/en-us/knowledge-center/knowledge/full-rgb-vs-limited-rgb-is-there-a-difference.html#:~:text=Full%20RGB%20means%20the%20ability,less%20dark)%20than%20full%20RGB > ). That is a very nice link, thanks! But to me it seems the section "Why is this a problem?" gets "crushed blacks" backwards, so maybe I just don't get it. I would assume that if the source (computer) sends full-range pixel values on the wire and the sink (monitor) works in limited-range mode, then you would get crushed blacks and crushed whites. But if the source sends limited-range data and the sink works in full-range more, you'd get the "washed out" image. My thinking comes from the mapping of channel values: if 0-16 and 235-255 ranges show no difference within them, I'd call that "crushed". Similarly if one assumes 16 is darkest black and it's actually not, you'd get "washed out" (I might call it compressed instead, because it affects both black and white ends, unable to achieve both the darkest black and the brightest white). Anyway, I believe I do understand that if you have content in one range and the sink assumes a different range, the content will show poorly. I don't doubt that. My question instead is: why would it be bad to always convert everything to full-range inside the source (e.g. decoder -> app -> display server all in full-range), and then convert for the wire into what the sink expects? Because that is how Wayland color management is going to handle differing color spaces, more or less. (Actually, quite likely the
Re: Dynamically change enumeration list of DRM enumeration property
Inline.. On Mon, Jun 1, 2020 at 2:19 PM Pekka Paalanen wrote: > On Mon, 1 Jun 2020 09:22:27 +0530 > Yogish Kulkarni wrote: > > > Hi, > > > > For letting DRM clients to select output encoding: > > Sink can support certain display timings with high output bit-depths > using > > multiple output encodings, e.g. sink can support a particular timing with > > RGB 10-bit, YCbCr422 10-bit and YCbCr420 10-bit. So DRM client may want > to > > select YCbCr422 10-bit over RBG 10-bit output to reduce the link > bandwidth > > (and in turn reduce power/voltage). If DRM driver automatically selects > > output encoding then we are restricting DRM clients from making > appropriate > > choice. > > Hi, > > right, that seems to be another reason. > > > For selectable output color range: > > Certain applications (typically graphics) usually rendered in full range > > while some applications (typically video) have limited range content. > Since > > content can change dynamically, DRM driver does not have enough > information > > to choose correct quantization. Only DRM client can correctly select > which > > quantization to set (to preserve artist's intent). > > Now this is an interesting topic for me. As far as I know, there is no > window system protocol to tell the display server whether the > application provided content is using full or limited range. This means > that the display server cannot tell DRM about full vs. limited range > either. It also means that when not fullscreen, the display server > cannot show the limited range video content correctly, because it would > have to be converted to full-range (or vice versa). > > Right, but there could be DRM client which doesn't use window system (e.g. Gstreamer video sink) and wants to select between full/limited color range. I agree that there is no window system protocol yet but maybe Wayland protocol could be added/extended for this purpose once we finalize things that needs to be done in DRM. But why would an application produce limited range pixels anyway? Is it > common that hardware video decoders are unable to produce full-range > pixels? > The primary reason for why content producer masters video/gfx content as limited range is for compatibility with sinks which only support limited range, and not because video decoders are not capable of decoding full-range content. Also, certain cinema-related content (e.g., movies) may be better suited for limited range encoding due to the level of detail that they need to present/hide (see "Why does limited RGB even exist?" section in https://www.benq.com/en-us/knowledge-center/knowledge/full-rgb-vs-limited-rgb-is-there-a-difference.html#:~:text=Full%20RGB%20means%20the%20ability,less%20dark)%20than%20full%20RGB ). I am asking, because I have a request to add limited vs. full range > information to Wayland. > > What about video sinks, including monitors? Are there devices that > accept limited-range only, full-range only, or switchable? > Yes, there are sinks which support selectable quantization range and there are sinks which don't. If the quantization range is not selectable, then in general, sources should output full-range for IT timings, and output limited for CE timings. At a high-level, IT timings are part of a standard developed by VESA for computer monitor-like displays. CE (Consumer Electronics) timings are a separate standard for timings more applicable to sinks like consumer TVs, etc. > > Why not just always use full-range everywhere? > > Or if a sink supports only limited-range, have the display chip > automatically convert from full-range, so that software doesn't have to > convert in software. > I think it is ok to convert from limited range to full range in display HW pipeline. By "automatically" if you mean display HW or DRM driver should look at the content to figure out whether it is limited range content and then program display pipeline to do the conversion, I don't think that is a good idea since we would need to inspect each pixel. Also, there may be some post-processing done to full-range content that happens to cause the pixel component values to fall within the limited quantization range. How about adding a new DRM KMS plane property to let client convey the driver about input content range? More details on this below. > > If you actually have a DRM KMS property for the range, does it mean that: > - the sink is configured to accept that range, and the pixels in the > framebuffer need to comply, or > - the display chip converts to that range while framebuffer remains in > full-range? > I would imagine this as: (1) Add new read DRM KMS connector property which DRM client will read to know whether sink support selectable quantization range. (2) Add new read/write DRM KMS connector property which DRM client will write to set output quantization range and read to know the current output quantization range. (3) Add new read/write DRM KMS plane property which DRM client will write to set
Re: Dynamically change enumeration list of DRM enumeration property
On Mon, 1 Jun 2020 09:22:27 +0530 Yogish Kulkarni wrote: > Hi, > > For letting DRM clients to select output encoding: > Sink can support certain display timings with high output bit-depths using > multiple output encodings, e.g. sink can support a particular timing with > RGB 10-bit, YCbCr422 10-bit and YCbCr420 10-bit. So DRM client may want to > select YCbCr422 10-bit over RBG 10-bit output to reduce the link bandwidth > (and in turn reduce power/voltage). If DRM driver automatically selects > output encoding then we are restricting DRM clients from making appropriate > choice. Hi, right, that seems to be another reason. > For selectable output color range: > Certain applications (typically graphics) usually rendered in full range > while some applications (typically video) have limited range content. Since > content can change dynamically, DRM driver does not have enough information > to choose correct quantization. Only DRM client can correctly select which > quantization to set (to preserve artist's intent). Now this is an interesting topic for me. As far as I know, there is no window system protocol to tell the display server whether the application provided content is using full or limited range. This means that the display server cannot tell DRM about full vs. limited range either. It also means that when not fullscreen, the display server cannot show the limited range video content correctly, because it would have to be converted to full-range (or vice versa). But why would an application produce limited range pixels anyway? Is it common that hardware video decoders are unable to produce full-range pixels? I am asking, because I have a request to add limited vs. full range information to Wayland. What about video sinks, including monitors? Are there devices that accept limited-range only, full-range only, or switchable? Why not just always use full-range everywhere? Or if a sink supports only limited-range, have the display chip automatically convert from full-range, so that software doesn't have to convert in software. If you actually have a DRM KMS property for the range, does it mean that: - the sink is configured to accept that range, and the pixels in the framebuffer need to comply, or - the display chip converts to that range while framebuffer remains in full-range? If we look at I915 driver's "Broadcast RGB" property, it seems to say to me that the framebuffer is always primarily assumed to be in full-range, and the conversion to limited-range happens in the scanout circuitry. So that property would not help with video content that is already in limited-range. To recap, there are two orthogonal things: application content or framebuffer range, and video sink / monitor range. The display server between the two, at last if it is a Wayland compositor, would be able to convert as necessary. > For how to use selectable output encoding with Weston: > I was thinking that DRM should have separate property to list the encodings > supported by sink and Weston will present this list to its client. Your Not client. A configuration tool perhaps, but not generically to all Wayland clients, not as a directly settable knob at least. > idea to validate encodings using TEST_ONLY commit and present a list of > timings along with encodings supported by particular timing seems better. > Instead of validating all possible encodings, does it make sense to > validate only those supported by sink? Irrespective of this we would Yes, having a list of what the sink actually supports would be nice. As for Wayland clients, there is an extension brewing at https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/8 that would allow suggesting the optimal encoding (pixel format and modifier really) in flight. That said, we are talking about the two different things here: framebuffer format vs. encoding on the wire. Whether making them match has benefits is another matter. > anyway need some mechanism which will allow user to select particular > encoding for a particular mode. I was thinking to allow this using new DRM > property "Encoding". Do you have anything better in mind? I think that is a reasonable and useful goal and idea. Just remember to document it when proposing, even if it seems obvious. The details on how to formulate that into UAPI is up for debate. As said, changing KMS properties after they have been exposed to userspace won't really work from either kernel or userspace point of view. So you'd probably need to expose one blob type property listing the encodings that may work as an array, and another property for setting the one to use. IN_FORMATS property is somewhat similar, although more complicated because it is the combination of format and modifier. > (Since I am using my Gmail Id, I feel I should mention that I work at > Nvidia) Nice to know the source of interest. :-) Thanks, pq > > Thanks, > -Yogish > > On Thu, May 28, 2020 at 6:18 PM Pekka
Re: Dynamically change enumeration list of DRM enumeration property
Hi, For letting DRM clients to select output encoding: Sink can support certain display timings with high output bit-depths using multiple output encodings, e.g. sink can support a particular timing with RGB 10-bit, YCbCr422 10-bit and YCbCr420 10-bit. So DRM client may want to select YCbCr422 10-bit over RBG 10-bit output to reduce the link bandwidth (and in turn reduce power/voltage). If DRM driver automatically selects output encoding then we are restricting DRM clients from making appropriate choice. For selectable output color range: Certain applications (typically graphics) usually rendered in full range while some applications (typically video) have limited range content. Since content can change dynamically, DRM driver does not have enough information to choose correct quantization. Only DRM client can correctly select which quantization to set (to preserve artist's intent). For how to use selectable output encoding with Weston: I was thinking that DRM should have separate property to list the encodings supported by sink and Weston will present this list to its client. Your idea to validate encodings using TEST_ONLY commit and present a list of timings along with encodings supported by particular timing seems better. Instead of validating all possible encodings, does it make sense to validate only those supported by sink? Irrespective of this we would anyway need some mechanism which will allow user to select particular encoding for a particular mode. I was thinking to allow this using new DRM property "Encoding". Do you have anything better in mind? (Since I am using my Gmail Id, I feel I should mention that I work at Nvidia) Thanks, -Yogish On Thu, May 28, 2020 at 6:18 PM Pekka Paalanen wrote: > On Thu, 28 May 2020 17:38:59 +0530 > Yogish Kulkarni wrote: > > > I am trying to find a way through Weston which will allow setting > specific > > encoding at display output. > > Hi, > > why do *you* want to control that? > > Why not let the driver always choose the highest possible encoding > given the video mode and hardware capability? > > I can understand userspace wanting to know what it got, but why should > userspace be able to control it? > > Would people want to pick the encoding first, and then go for the > highest possible video mode? > > > Could you please elaborate on why it is best > > to let DRM driver automatically configure which encoding to choose rather > > than making it selectable by DRM client ? I am not able to find reference > > to past discussion about this. I was only able to find a proposed change > - > > https://lists.freedesktop.org/archives/intel-gfx/2017-April/125451.html > but > > am not able to find why it got rejected. > > > > Alternatively, is there existing way through which DRM clients can > specify > > preference for output encoding ? Or currently it's all up to the DRM > driver > > to choose what output encoding to use. > > There must be some reason why userspace needs to be able to control it. > I'm also asking as a Weston maintainer, since I'm interested in how > this affects e.g. color reproduction or HDR support. > > One thing that comes to my mind is using atomic TEST_ONLY commits to > probe all the possible video modes × encodings for presenting a list to > the user to choose from, if you have a display configuration GUI. E.g > with some TV use cases, maybe the user wants to avoid sub-sampling, use > the native resolution, but limit refresh rate to what's actually > possible. Or any other combination of the three. > > > Thanks, > pq > > > > > Thanks, > > -Yogish > > > > On Thu, May 28, 2020 at 1:54 PM Daniel Vetter wrote: > > > > > On Thu, May 28, 2020 at 12:29:43PM +0530, Yogish Kulkarni wrote: > > > > For creating new source property, is it good to follow > > > > "drm_mode_create_hdmi_colorspace_property()" as an example ? It > seems > > > that > > > > currently there is no standard DRM property which allows DRM client > to > > > set > > > > a specific output encoding (like YUV420, YUV422 etc). Also, there is > no > > > > standard property for letting client select YUV/RGB color range. I > see > > > > there are two ways to introduce new properties, 1. do something like > > > > drm_mode_create_hdmi_colorspace_property 2. create custom property > > > similar > > > > to "Broadcast RGB". Is there opinion on which is a preferable way > to > > > expose > > > > encoding and color rage selection property ? > > > > > > I guess first question is "why?" Thus far we've gone with the opinion > that > > > automatically configuring output stuff as much as possible is best. > What's > > > the use-case where the driver can't select this? > > > -Daniel > ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Dynamically change enumeration list of DRM enumeration property
On Thu, 28 May 2020 17:38:59 +0530 Yogish Kulkarni wrote: > I am trying to find a way through Weston which will allow setting specific > encoding at display output. Hi, why do *you* want to control that? Why not let the driver always choose the highest possible encoding given the video mode and hardware capability? I can understand userspace wanting to know what it got, but why should userspace be able to control it? Would people want to pick the encoding first, and then go for the highest possible video mode? > Could you please elaborate on why it is best > to let DRM driver automatically configure which encoding to choose rather > than making it selectable by DRM client ? I am not able to find reference > to past discussion about this. I was only able to find a proposed change - > https://lists.freedesktop.org/archives/intel-gfx/2017-April/125451.html but > am not able to find why it got rejected. > > Alternatively, is there existing way through which DRM clients can specify > preference for output encoding ? Or currently it's all up to the DRM driver > to choose what output encoding to use. There must be some reason why userspace needs to be able to control it. I'm also asking as a Weston maintainer, since I'm interested in how this affects e.g. color reproduction or HDR support. One thing that comes to my mind is using atomic TEST_ONLY commits to probe all the possible video modes × encodings for presenting a list to the user to choose from, if you have a display configuration GUI. E.g with some TV use cases, maybe the user wants to avoid sub-sampling, use the native resolution, but limit refresh rate to what's actually possible. Or any other combination of the three. Thanks, pq > > Thanks, > -Yogish > > On Thu, May 28, 2020 at 1:54 PM Daniel Vetter wrote: > > > On Thu, May 28, 2020 at 12:29:43PM +0530, Yogish Kulkarni wrote: > > > For creating new source property, is it good to follow > > > "drm_mode_create_hdmi_colorspace_property()" as an example ? It seems > > that > > > currently there is no standard DRM property which allows DRM client to > > set > > > a specific output encoding (like YUV420, YUV422 etc). Also, there is no > > > standard property for letting client select YUV/RGB color range. I see > > > there are two ways to introduce new properties, 1. do something like > > > drm_mode_create_hdmi_colorspace_property 2. create custom property > > similar > > > to "Broadcast RGB". Is there opinion on which is a preferable way to > > expose > > > encoding and color rage selection property ? > > > > I guess first question is "why?" Thus far we've gone with the opinion that > > automatically configuring output stuff as much as possible is best. What's > > the use-case where the driver can't select this? > > -Daniel pgpOB1bCPb_Bt.pgp Description: OpenPGP digital signature ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Dynamically change enumeration list of DRM enumeration property
I am trying to find a way through Weston which will allow setting specific encoding at display output. Could you please elaborate on why it is best to let DRM driver automatically configure which encoding to choose rather than making it selectable by DRM client ? I am not able to find reference to past discussion about this. I was only able to find a proposed change - https://lists.freedesktop.org/archives/intel-gfx/2017-April/125451.html but am not able to find why it got rejected. Alternatively, is there existing way through which DRM clients can specify preference for output encoding ? Or currently it's all up to the DRM driver to choose what output encoding to use. Thanks, -Yogish On Thu, May 28, 2020 at 1:54 PM Daniel Vetter wrote: > On Thu, May 28, 2020 at 12:29:43PM +0530, Yogish Kulkarni wrote: > > For creating new source property, is it good to follow > > "drm_mode_create_hdmi_colorspace_property()" as an example ? It seems > that > > currently there is no standard DRM property which allows DRM client to > set > > a specific output encoding (like YUV420, YUV422 etc). Also, there is no > > standard property for letting client select YUV/RGB color range. I see > > there are two ways to introduce new properties, 1. do something like > > drm_mode_create_hdmi_colorspace_property 2. create custom property > similar > > to "Broadcast RGB". Is there opinion on which is a preferable way to > expose > > encoding and color rage selection property ? > > I guess first question is "why?" Thus far we've gone with the opinion that > automatically configuring output stuff as much as possible is best. What's > the use-case where the driver can't select this? > -Daniel > > > > > Thanks, > > -Yogish > > > > On Tue, May 26, 2020 at 5:44 PM Daniel Vetter wrote: > > > > > On Tue, May 26, 2020 at 9:39 AM Pekka Paalanen > > > wrote: > > > > > > > > On Tue, 26 May 2020 10:01:23 +0530 > > > > Yogish Kulkarni wrote: > > > > > > > > > Hi, > > > > > > > > > > Is it possible to dynamically change enumeration list of DRM > > > enumeration > > > > > property ? Motivation behind this question is to understand > whether it > > > is > > > > > possible to create connector enum property (e.g a property which > will > > > list > > > > > supported output encodings - like yuv420, yuv422 etc) whose list > of > > > > > supported enum values could be changed dynamically e.g. based on > which > > > sink > > > > > is connected. > > > > > > > > > > I think there is existing EDID connector property whose value > changes > > > based > > > > > on connected sink. EDID is a BLOB property, I am trying to > understand > > > if > > > > > this is also possible for ENUM type property. There is > > > > > "drm_property_replace_blob" to replace blob but I wasn't able to > find > > > any > > > > > API which could replace list of supported enums. Alternatively, > would > > > it be > > > > > good idea to destroy custom enum property created by a driver and > > > create > > > > > new enum property with new list of supported enums e.g when there > is a > > > > > HOTPLUG event. > > > > > > > > Hi, > > > > > > > > looking at Weston code, it *might* cope with it. A hotplug event does > > > > cause Weston to re-discover all properties of a connector. This is > > > > specific to connectors only. > > > > > > Currently the kernel doesn't cope with that. Only objects which can be > > > added/removed are connectors, blobs and fbs (iow the refcounted ones). > > > Adding/removing properties isn't supported, nor is adding/removing > > > which properties are attached to which object while that object is > > > life. > > > > > > Also I think the uapi risk for this is way too big, see my other reply > > > for what we've done in the past for stuff like this. > > > -Daniel > > > > > > > The race exists though: userspace might be poking at KMS after you > > > > changed the property in the kernel but before userspace handles the > > > > hotplug event. You'd have to check that does not cause regressions. I > > > > guess for a completely new property, the risk seems low, as userspace > > > > does not know to poke at it (risk of using outdated property
Re: Dynamically change enumeration list of DRM enumeration property
On Thu, May 28, 2020 at 12:29:43PM +0530, Yogish Kulkarni wrote: > For creating new source property, is it good to follow > "drm_mode_create_hdmi_colorspace_property()" as an example ? It seems that > currently there is no standard DRM property which allows DRM client to set > a specific output encoding (like YUV420, YUV422 etc). Also, there is no > standard property for letting client select YUV/RGB color range. I see > there are two ways to introduce new properties, 1. do something like > drm_mode_create_hdmi_colorspace_property 2. create custom property similar > to "Broadcast RGB". Is there opinion on which is a preferable way to expose > encoding and color rage selection property ? I guess first question is "why?" Thus far we've gone with the opinion that automatically configuring output stuff as much as possible is best. What's the use-case where the driver can't select this? -Daniel > > Thanks, > -Yogish > > On Tue, May 26, 2020 at 5:44 PM Daniel Vetter wrote: > > > On Tue, May 26, 2020 at 9:39 AM Pekka Paalanen > > wrote: > > > > > > On Tue, 26 May 2020 10:01:23 +0530 > > > Yogish Kulkarni wrote: > > > > > > > Hi, > > > > > > > > Is it possible to dynamically change enumeration list of DRM > > enumeration > > > > property ? Motivation behind this question is to understand whether it > > is > > > > possible to create connector enum property (e.g a property which will > > list > > > > supported output encodings - like yuv420, yuv422 etc) whose list of > > > > supported enum values could be changed dynamically e.g. based on which > > sink > > > > is connected. > > > > > > > > I think there is existing EDID connector property whose value changes > > based > > > > on connected sink. EDID is a BLOB property, I am trying to understand > > if > > > > this is also possible for ENUM type property. There is > > > > "drm_property_replace_blob" to replace blob but I wasn't able to find > > any > > > > API which could replace list of supported enums. Alternatively, would > > it be > > > > good idea to destroy custom enum property created by a driver and > > create > > > > new enum property with new list of supported enums e.g when there is a > > > > HOTPLUG event. > > > > > > Hi, > > > > > > looking at Weston code, it *might* cope with it. A hotplug event does > > > cause Weston to re-discover all properties of a connector. This is > > > specific to connectors only. > > > > Currently the kernel doesn't cope with that. Only objects which can be > > added/removed are connectors, blobs and fbs (iow the refcounted ones). > > Adding/removing properties isn't supported, nor is adding/removing > > which properties are attached to which object while that object is > > life. > > > > Also I think the uapi risk for this is way too big, see my other reply > > for what we've done in the past for stuff like this. > > -Daniel > > > > > The race exists though: userspace might be poking at KMS after you > > > changed the property in the kernel but before userspace handles the > > > hotplug event. You'd have to check that does not cause regressions. I > > > guess for a completely new property, the risk seems low, as userspace > > > does not know to poke at it (risk of using outdated property or value > > > IDs causing unexpected atomic commit failure). Also I'm not aware of > > > any KMS program that would yet attempt blind KMS state save & restore > > > to sanitize the KMS state after dropping and re-gaining DRM master. > > > > > > You'd have to check all other KMS using programs too: every Wayland > > > compositor, Xorg, DRM Vulkan WSI(?), ... > > > > > > > > > Thanks, > > > pq > > > ___ > > > dri-devel mailing list > > > dri-devel@lists.freedesktop.org > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > > > > > -- > > Daniel Vetter > > Software Engineer, Intel Corporation > > +41 (0) 79 365 57 48 - http://blog.ffwll.ch > > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Dynamically change enumeration list of DRM enumeration property
For creating new source property, is it good to follow "drm_mode_create_hdmi_colorspace_property()" as an example ? It seems that currently there is no standard DRM property which allows DRM client to set a specific output encoding (like YUV420, YUV422 etc). Also, there is no standard property for letting client select YUV/RGB color range. I see there are two ways to introduce new properties, 1. do something like drm_mode_create_hdmi_colorspace_property 2. create custom property similar to "Broadcast RGB". Is there opinion on which is a preferable way to expose encoding and color rage selection property ? Thanks, -Yogish On Tue, May 26, 2020 at 5:44 PM Daniel Vetter wrote: > On Tue, May 26, 2020 at 9:39 AM Pekka Paalanen > wrote: > > > > On Tue, 26 May 2020 10:01:23 +0530 > > Yogish Kulkarni wrote: > > > > > Hi, > > > > > > Is it possible to dynamically change enumeration list of DRM > enumeration > > > property ? Motivation behind this question is to understand whether it > is > > > possible to create connector enum property (e.g a property which will > list > > > supported output encodings - like yuv420, yuv422 etc) whose list of > > > supported enum values could be changed dynamically e.g. based on which > sink > > > is connected. > > > > > > I think there is existing EDID connector property whose value changes > based > > > on connected sink. EDID is a BLOB property, I am trying to understand > if > > > this is also possible for ENUM type property. There is > > > "drm_property_replace_blob" to replace blob but I wasn't able to find > any > > > API which could replace list of supported enums. Alternatively, would > it be > > > good idea to destroy custom enum property created by a driver and > create > > > new enum property with new list of supported enums e.g when there is a > > > HOTPLUG event. > > > > Hi, > > > > looking at Weston code, it *might* cope with it. A hotplug event does > > cause Weston to re-discover all properties of a connector. This is > > specific to connectors only. > > Currently the kernel doesn't cope with that. Only objects which can be > added/removed are connectors, blobs and fbs (iow the refcounted ones). > Adding/removing properties isn't supported, nor is adding/removing > which properties are attached to which object while that object is > life. > > Also I think the uapi risk for this is way too big, see my other reply > for what we've done in the past for stuff like this. > -Daniel > > > The race exists though: userspace might be poking at KMS after you > > changed the property in the kernel but before userspace handles the > > hotplug event. You'd have to check that does not cause regressions. I > > guess for a completely new property, the risk seems low, as userspace > > does not know to poke at it (risk of using outdated property or value > > IDs causing unexpected atomic commit failure). Also I'm not aware of > > any KMS program that would yet attempt blind KMS state save & restore > > to sanitize the KMS state after dropping and re-gaining DRM master. > > > > You'd have to check all other KMS using programs too: every Wayland > > compositor, Xorg, DRM Vulkan WSI(?), ... > > > > > > Thanks, > > pq > > ___ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch > ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Dynamically change enumeration list of DRM enumeration property
On Tue, May 26, 2020 at 9:39 AM Pekka Paalanen wrote: > > On Tue, 26 May 2020 10:01:23 +0530 > Yogish Kulkarni wrote: > > > Hi, > > > > Is it possible to dynamically change enumeration list of DRM enumeration > > property ? Motivation behind this question is to understand whether it is > > possible to create connector enum property (e.g a property which will list > > supported output encodings - like yuv420, yuv422 etc) whose list of > > supported enum values could be changed dynamically e.g. based on which sink > > is connected. > > > > I think there is existing EDID connector property whose value changes based > > on connected sink. EDID is a BLOB property, I am trying to understand if > > this is also possible for ENUM type property. There is > > "drm_property_replace_blob" to replace blob but I wasn't able to find any > > API which could replace list of supported enums. Alternatively, would it be > > good idea to destroy custom enum property created by a driver and create > > new enum property with new list of supported enums e.g when there is a > > HOTPLUG event. > > Hi, > > looking at Weston code, it *might* cope with it. A hotplug event does > cause Weston to re-discover all properties of a connector. This is > specific to connectors only. Currently the kernel doesn't cope with that. Only objects which can be added/removed are connectors, blobs and fbs (iow the refcounted ones). Adding/removing properties isn't supported, nor is adding/removing which properties are attached to which object while that object is life. Also I think the uapi risk for this is way too big, see my other reply for what we've done in the past for stuff like this. -Daniel > The race exists though: userspace might be poking at KMS after you > changed the property in the kernel but before userspace handles the > hotplug event. You'd have to check that does not cause regressions. I > guess for a completely new property, the risk seems low, as userspace > does not know to poke at it (risk of using outdated property or value > IDs causing unexpected atomic commit failure). Also I'm not aware of > any KMS program that would yet attempt blind KMS state save & restore > to sanitize the KMS state after dropping and re-gaining DRM master. > > You'd have to check all other KMS using programs too: every Wayland > compositor, Xorg, DRM Vulkan WSI(?), ... > > > Thanks, > pq > ___ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Dynamically change enumeration list of DRM enumeration property
Thanks, Daniel & Pekka. It might be bad idea to destroy and re-create the connector enum property from HOTPLUG handler in DRM. But if this is done through DRM_IOCTL_MODE_GETCONNECTOR, there won't be race, right ? From code walk through it seems that Weston will call this IOCTL for newly connected display found through HOTPLUG event and DRM driver will update the EDID through the call sequence triggered by this IOCTL. On the similar line if existing connector property is destroyed and re-created with new enmu list through this IOCTL call chain, then there won't be race ? Thanks, -Yogish On Tue, May 26, 2020 at 1:09 PM Pekka Paalanen wrote: > On Tue, 26 May 2020 10:01:23 +0530 > Yogish Kulkarni wrote: > > > Hi, > > > > Is it possible to dynamically change enumeration list of DRM enumeration > > property ? Motivation behind this question is to understand whether it is > > possible to create connector enum property (e.g a property which will > list > > supported output encodings - like yuv420, yuv422 etc) whose list of > > supported enum values could be changed dynamically e.g. based on which > sink > > is connected. > > > > I think there is existing EDID connector property whose value changes > based > > on connected sink. EDID is a BLOB property, I am trying to understand if > > this is also possible for ENUM type property. There is > > "drm_property_replace_blob" to replace blob but I wasn't able to find any > > API which could replace list of supported enums. Alternatively, would it > be > > good idea to destroy custom enum property created by a driver and create > > new enum property with new list of supported enums e.g when there is a > > HOTPLUG event. > > Hi, > > looking at Weston code, it *might* cope with it. A hotplug event does > cause Weston to re-discover all properties of a connector. This is > specific to connectors only. > > The race exists though: userspace might be poking at KMS after you > changed the property in the kernel but before userspace handles the > hotplug event. You'd have to check that does not cause regressions. I > guess for a completely new property, the risk seems low, as userspace > does not know to poke at it (risk of using outdated property or value > IDs causing unexpected atomic commit failure). Also I'm not aware of > any KMS program that would yet attempt blind KMS state save & restore > to sanitize the KMS state after dropping and re-gaining DRM master. > > You'd have to check all other KMS using programs too: every Wayland > compositor, Xorg, DRM Vulkan WSI(?), ... > > > Thanks, > pq > ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Dynamically change enumeration list of DRM enumeration property
On Tue, 26 May 2020 10:01:23 +0530 Yogish Kulkarni wrote: > Hi, > > Is it possible to dynamically change enumeration list of DRM enumeration > property ? Motivation behind this question is to understand whether it is > possible to create connector enum property (e.g a property which will list > supported output encodings - like yuv420, yuv422 etc) whose list of > supported enum values could be changed dynamically e.g. based on which sink > is connected. > > I think there is existing EDID connector property whose value changes based > on connected sink. EDID is a BLOB property, I am trying to understand if > this is also possible for ENUM type property. There is > "drm_property_replace_blob" to replace blob but I wasn't able to find any > API which could replace list of supported enums. Alternatively, would it be > good idea to destroy custom enum property created by a driver and create > new enum property with new list of supported enums e.g when there is a > HOTPLUG event. Hi, looking at Weston code, it *might* cope with it. A hotplug event does cause Weston to re-discover all properties of a connector. This is specific to connectors only. The race exists though: userspace might be poking at KMS after you changed the property in the kernel but before userspace handles the hotplug event. You'd have to check that does not cause regressions. I guess for a completely new property, the risk seems low, as userspace does not know to poke at it (risk of using outdated property or value IDs causing unexpected atomic commit failure). Also I'm not aware of any KMS program that would yet attempt blind KMS state save & restore to sanitize the KMS state after dropping and re-gaining DRM master. You'd have to check all other KMS using programs too: every Wayland compositor, Xorg, DRM Vulkan WSI(?), ... Thanks, pq pgpj4PR91PW3k.pgp Description: OpenPGP digital signature ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Dynamically change enumeration list of DRM enumeration property
On Tue, May 26, 2020 at 6:31 AM Yogish Kulkarni wrote: > > Hi, > > Is it possible to dynamically change enumeration list of DRM enumeration > property ? Motivation behind this question is to understand whether it is > possible to create connector enum property (e.g a property which will list > supported output encodings - like yuv420, yuv422 etc) whose list of > supported enum values could be changed dynamically e.g. based on which sink > is connected. > > I think there is existing EDID connector property whose value changes based > on connected sink. EDID is a BLOB property, I am trying to understand if this > is also possible for ENUM type property. There is "drm_property_replace_blob" > to replace blob but I wasn't able to find any API which could replace list of > supported enums. Alternatively, would it be good idea to destroy custom enum > property created by a driver and create new enum property with new list of > supported enums e.g when there is a HOTPLUG event. Neither works, properties and their value ranges are static. Also generally the idea is that the properties on the drm_connector reflect what the source side can do, irrespective of the sink capabilities. Since a lot of sinks have bad EDID and you might want to overwrite what the sink claims works. Usually how we do this is a second property that the kernel sets, and userspace can only read, which shows what the sink is capable of. Sometimes we also just let userspace re-decode the EDID and figure that out itself, but that's kinda a bad interface. Also for anything new, please keep in mind our rules for new uapi: https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#testing-and-validation Cheers, Daniel -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Dynamically change enumeration list of DRM enumeration property
Hi, Is it possible to dynamically change enumeration list of DRM enumeration property ? Motivation behind this question is to understand whether it is possible to create connector enum property (e.g a property which will list supported output encodings - like yuv420, yuv422 etc) whose list of supported enum values could be changed dynamically e.g. based on which sink is connected. I think there is existing EDID connector property whose value changes based on connected sink. EDID is a BLOB property, I am trying to understand if this is also possible for ENUM type property. There is "drm_property_replace_blob" to replace blob but I wasn't able to find any API which could replace list of supported enums. Alternatively, would it be good idea to destroy custom enum property created by a driver and create new enum property with new list of supported enums e.g when there is a HOTPLUG event. Thanks, -Yogish ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
