On Thu, Mar 8, 2018 at 11:29 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote: > On Mon, Mar 5, 2018 at 7:33 AM, Ilia Mirkin <imir...@alum.mit.edu> wrote: >> On Mon, Mar 5, 2018 at 1:17 AM, Mario Kleiner >> <mario.kleiner...@gmail.com> wrote: >>> On 03/03/2018 12:59 AM, Ilia Mirkin wrote: >>>> >>>> On Fri, Mar 2, 2018 at 6:46 PM, Mario Kleiner >>>> <mario.kleiner...@gmail.com> wrote: >>>>> >>>>> On 03/02/2018 11:29 PM, Ilia Mirkin wrote: >>>>>> >>>>>> OK, so even if you're passing 1024 to xf86HandleColormaps, gamma_set >>>>>> still only gets called with a 256-entry LUT? If so, that works nicely >>>>>> here, but is not intuitive :) >>>>> >>>>> >>>>> Yes. Lots of remapping in the server, i get dizzy everytime i look at it, >>>>> and forget almost immediately how stuff fits together when i don't look >>>>> at >>>>> it. Anyway, the final downsampling from 1024 -> 256 hw lut happens in >>>>> xf86RandR12CrtcComputeGamma(), see >>>>> >>>>> >>>>> https://cgit.freedesktop.org/xorg/xserver/commit/?id=b5f9fcd50a999a00128c0cc3f6e7d1f66182c9d5 >>>>> >>>>> for the latest. I'll propose that one to get cherry-picked into the >>>>> server-1.19 branch as well. >>>> >>>> >>>> Hrmph. That means we should try to adjust the gamma_set helper to do >>>> the sampling when receiving a 1024-sized LUT, if people will use older >>>> X servers (seems likely). Should hopefully be straightforward, to >>>> handle just that one case. >>> >>> >>> I think we never receive anything but a 256 slot LUT via gamma_set afaics? >>> The server initializes xf86Crtc's gamma_size to 256 at startup, and none of >>> the ddx'es ever overrides that with actual info from the kernel. >>> >>> What happens on older servers without that patch iff color depth 30 is >>> selected is simply that the gamma table updates no-op, so the server runs >>> with an identity gamma table setup at startup. Not perfect, but also not >>> that bad, given that probably most people run their setups with a gamma of >>> 1.0 anyway. At default depth 24 stuff works as usual. >> >> Ah OK. That's not so bad. I'll try to play around with it this week. >> Thanks for the explanation! > > I just tested this out against xorg 1.19.5. With your patch, I get an > extremely dark screen. I think it's just getting the first 256 of the > 1024 values (I checked -- gamma_set is still only getting 256 values). > So we have to do something a bit cleverer to fix this scenario... > ideas?
Mario, Have you given this any thought? Is there a way to detect one or the other scenario? I'd rather not put something in where we check the X version at compile time. Did the ABI get bumped in 1.20 perhaps? -ilia _______________________________________________ Nouveau mailing list Nouveau@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/nouveau
