Em 29-06-2011 09:51, Tomasz Stanislawski escreveu:
> The 1080p59_94 is supported by latest Samsung SoC.
>
> Signed-off-by: Tomasz Stanislawski <[email protected]>
> Signed-off-by: Kyungmin Park <[email protected]>
> Reviewed-by: Hans Verkuil <[email protected]>
> ---
> drivers/media/video/v4l2-common.c | 1 +
> include/linux/videodev2.h | 1 +
> 2 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/media/video/v4l2-common.c
> b/drivers/media/video/v4l2-common.c
> index 06b9f9f..003e648 100644
> --- a/drivers/media/video/v4l2-common.c
> +++ b/drivers/media/video/v4l2-common.c
> @@ -582,6 +582,7 @@ int v4l_fill_dv_preset_info(u32 preset, struct
> v4l2_dv_enum_preset *info)
> { 1920, 1080, "1080p@30" }, /* V4L2_DV_1080P30 */
> { 1920, 1080, "1080p@50" }, /* V4L2_DV_1080P50 */
> { 1920, 1080, "1080p@60" }, /* V4L2_DV_1080P60 */
> + { 1920, 1080, "[email protected]" }, /* V4L2_DV_1080P59_94 */
> };
>
> if (info == NULL || preset >= ARRAY_SIZE(dv_presets))
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index 8a4c309..7c77c4e 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -872,6 +872,7 @@ struct v4l2_dv_enum_preset {
> #define V4L2_DV_1080P30 16 /* SMPTE 296M */
> #define V4L2_DV_1080P50 17 /* BT.1120 */
> #define V4L2_DV_1080P60 18 /* BT.1120 */
> +#define V4L2_DV_1080P59_94 19
>
> /*
> * D V B T T I M I N G S
This patch deserves further discussions, as the specs that define the presets
are not so clear with respect to 60Hz and 60/1.001 Hz.
Let me summarize the issue.
1) PRESET STANDARDS
====== =========
There are 3 specs involved with DV presets: ITU-R BT 709 and BT 1120 and CEA
861.
At ITU-R BT.709, both 60Hz and 60/1.001 Hz are equally called as "60 Hz".
BT.1120
follows the same logic, as it uses BT.709 as a reference for video timings.
The CEA-861-E spec says at item 4, that:
A video timing with a vertical frequency that is an integer multiple of
6.00 Hz (i.e. 24.00, 30.00, 60.00,
120.00 or 240.00 Hz) is considered to be the same as a video timing
with the equivalent detailed timing
information but where the vertical frequency is adjusted by a factor of
1000/1001 (i.e., 24/1.001, 30/1.001,
60/1.001, 120/1.001 or 240/1.001). That is, they are considered two
versions of the same video timing but
with slightly different pixel clock frequencies. Therefore, a DTV that
declares it is capable of displaying a
video timing with a vertical frequency that is either an integer
multiple of 6 Hz or an integer multiple of 6
Hz adjusted by a factor of 1000/1001 shall be capable of displaying
both versions of the video timing.
At the same item, the table 2 describes several video parameters for each
preset, associating the
Video Identification Codes (VIC) for each preset.
Table 4 associates each VIC with the supported formats. For example, VIC 16
means a resolution of
1920x1080 at 59.94Hz/60Hz. The spec does explicitly allow that all vertical
frequencies that are
multiple of 6 Hz to accept both 59.94 Hz and 60 Hz, as said at note 3 of table
2:
3. A video timing with a vertical frequency that is an integer multiple
of 6.00 Hz (i.e. 24.00, 30.00, 60.00, 120.00 or
240.00 Hz) is considered to be the same as a video timing with the
equivalent detailed timing information but where
the vertical frequency is adjusted by a factor of 1000/1001 (i.e.,
24/1.001, 30/1.001, 60/1.001, 120/1.001 or
240/1.001). That is, they are considered two versions of the same video
timing but with slightly different pixel clock
frequencies. The vertical frequencies of the 240p, 480p, and 480i video
formats are typically adjusted by a factor of
exactly 1000/1001 for NTSC video compatibility, while the 576p, 576i,
and the HDTV video formats are not. The
VESA DMT standard [65] specifies a ± 0.5% pixel clock frequency
tolerance. Therefore, the nominally 25.175 MHz
pixel clock frequency value given for video identification code 1 may
be adjusted to 25.2 MHz to obtain an exact 60
Hz vertical frequency.
In other words, the preset for 1920x1080p@60Hz can be used for both 60Hz and
59.94 Hz,
according with the above note, being 59.94 Hz the typical value (e. g. the
value that
should be used on most places).
However, there are some "60 Hz" vertical resolutions that have VIC's with
different framerates (like 59.94Hz, 60.054Hz, etc). Those seem to not be
covered by the "multiple of 6.00 Hz" rule.
2. V4L2 API
==== ===
The V4L2 specs define a DV timing as having those fields:
__u32 width Width of the active video in pixels
__u32 height Height of the active video in lines
__u32 interlaced Progressive (0) or interlaced (1)
__u32 polarities This is a bit mask that defines polarities of sync
signals.
__u64 pixelclock Pixel clock in Hz. Ex. 74.25MHz->74250000
__u32 hfrontporch Horizontal front porch in pixels
__u32 hsync Horizontal sync length in pixels
__u32 hbackporch Horizontal back porch in pixels
__u32 vfrontporch Vertical front porch in lines
__u32 vsync Vertical sync length in lines
__u32 vbackporch Vertical back porch in lines
__u32 il_vfrontporch Vertical front porch in lines for bottom field of
interlaced field formats
__u32 il_vsync Vertical sync length in lines for bottom field of
interlaced field formats
__u32 il_vbackporch Vertical back porch in lines for bottom field of
interlaced field formats
[1] http://linuxtv.org/downloads/v4l-dvb-apis/vidioc-g-dv-timings.html
So, it basically allows adjusting the timings for each of the VIC's, but it
seems that there
is one limitation at the current API:
vblank is an integer value, for both frames 0 and 1. So, it doesn't allow to
adjust vblanks
like 22.5. This prevents specifying presets like VICs 10/11.
The presets ioctl's [2] provide the following fields:
__u32 index Number of the DV preset, set by the application.
__u32 preset This field identifies one of the DV preset values listed in
Table A.15, “struct DV Presets”.
__u8 name[24] Name of the preset, a NUL-terminated ASCII string, for
example: "720P-60", "1080I-60". This information is intended for the user.
__u32 width Width of the active video in pixels for the DV preset.
__u32 height Height of the active video in lines for the DV preset.
[2]
http://linuxtv.org/downloads/v4l-dvb-apis/vidioc-enum-dv-presets.html#v4l2-dv-presets-vals
Where "preset" can mean:
V4L2_DV_INVALID 0 Invalid preset value.
V4L2_DV_480P59_94 1 720x480 progressive video at 59.94 fps as per
BT.1362.
V4L2_DV_576P50 2 720x576 progressive video at 50 fps as per
BT.1362.
V4L2_DV_720P24 3 1280x720 progressive video at 24 fps as per
SMPTE 296M.
V4L2_DV_720P25 4 1280x720 progressive video at 25 fps as per
SMPTE 296M.
V4L2_DV_720P30 5 1280x720 progressive video at 30 fps as per
SMPTE 296M.
V4L2_DV_720P50 6 1280x720 progressive video at 50 fps as per
SMPTE 296M.
V4L2_DV_720P59_94 7 1280x720 progressive video at 59.94 fps as per
SMPTE 274M.
V4L2_DV_720P60 8 1280x720 progressive video at 60 fps as per
SMPTE 274M/296M.
V4L2_DV_1080I29_97 9 1920x1080 interlaced video at 29.97 fps as per
BT.1120/SMPTE 274M.
V4L2_DV_1080I30 10 1920x1080 interlaced video at 30 fps as per
BT.1120/SMPTE 274M.
V4L2_DV_1080I25 11 1920x1080 interlaced video at 25 fps as per
BT.1120.
V4L2_DV_1080I50 12 1920x1080 interlaced video at 50 fps as per
SMPTE 296M.
V4L2_DV_1080I60 13 1920x1080 interlaced video at 60 fps as per
SMPTE 296M.
V4L2_DV_1080P24 14 1920x1080 progressive video at 24 fps as per
SMPTE 296M.
V4L2_DV_1080P25 15 1920x1080 progressive video at 25 fps as per
SMPTE 296M.
V4L2_DV_1080P30 16 1920x1080 progressive video at 30 fps as per
SMPTE 296M.
V4L2_DV_1080P50 17 1920x1080 progressive video at 50 fps as per
BT.1120.
V4L2_DV_1080P60 18 1920x1080 progressive video at 60 fps as per
BT.1120.
3. ISSUES AT V4L2 API
====== == ==== ===
There are some troubles at the way we currently define the presets:
3.1) The preset macros have the name of the active video lines, but this is
also present at
the height field;
3.2) The preset macros don't have the name of the active video columns;
3.3) If someone would want to add a preset for some CEA-861-E VICs, namespace
conflicts will
happen. For example, a preset for 1440x576@50Hz would have the same name
as a preset
for 2880x576p at 50 Hz. Both would be called as V4L2_DV_576P50.
3.4) It doesn't mind what DV timing is used, CEA-861-E and BT.709 allows to use
the 60Hz
timings as either 60Hz or 59.94 Hz. That applies to all VIC format timings
at table 2
for 60 Hz, 120 Hz and 240 Hz.
3.5) There are lots of format at CEA-861-E without a V4L2 preset.
4. PROPOSED SOLUTION
======== ========
In order to fix the issue, we need change the API without breaking the current
apps that
use the timings ioctls. Also, the vertical rate clock for 60Hz formats needs to
allow
a fractional adjustment of either 1 or 1000/1001, in order to support the specs.
4.1) Preset renaming
---------------
To avoid having duplicated namespace conflicts, the better seems to rename the
existing
presets to contain both width and height at their macro definitions, like:
#define V4L2_DV_1920_1080P60 18 1920x1080 progressive video at 60 fps
as per BT.1120
(for the sake of simplicity, I just took one value from the table. The same fix
is needed
to be applied for the other macro definitions)
To avoid breaking userspace, the old names need to be associated with the new
ones, with:
#define V4L2_DV_1080P60 V4L2_DV_1920_1080P60
This fixes issue 3.2 and 3.3. Unfortunately, fixing 3.1 is not possible
anymore, so,
we have to keep the same information duplicated on two places (at the macro
name and
at the width/height).
The question that remains unsolved is what an userspace application would
handle a driver
that might eventually provide inconsistent data at width/height and at the
macro names?
4.2) Framerate selection for 60Hz preset
-----------------------------------
As the spec allows using any format that it is multiple of 6.00 Hz multiplied
by either
1 or 1000/1001, the selection betweem them should be done via
VIDIOC_G_PARM/VIDIOC_S_PARM.
So, V4L2 spec should say, at the "Digital Video (DV) Timings" section:
Devices that implement DV timings shall implement
VIDIOC_G_PARM/VIDIOC_S_PARM,
in order to allow controlling the vertical frame rate for the presets
whose
vertical rate is multiple of 6.00 Hz, in order to allow setting the
timing
between 60 Hz and 59.94 Hz. The default value, at device init, shall be
59.94 Hz.
4.3) Add the missing CEA-861-E presets
---------------------------------
As those formats are part of the spec that is implemented by this V4L2 API, the
better
would be to implement all the missing formats at the V4L2 spec. As a generic
rule, we
don't add support at the Kernel without having a driver using it, but, in this
specific
case, we want to be able to be compatible with the specs, so, it seems a good
idea to
implement the remaining ones, or, at least reserve its namespace at the
DocBook. This
solves issue 3.5.
5) S5P-TV SUPPORT FOR 59.94 HZ
===========================
It is not clear, from this patch, if you're really wanting to implement support
for VIC
16 format @59.94 Hz, or something else. From CEA-861-E, it seems to be the
case, as
this is the only 1920x1080p format for 60 Hz. If this is the case, according
with my
proposal, the driver should be using the 60Hz format, instead, and implement
S_PARM
to allow selecting between 60Hz and 59.94Hz.
Comments?
Cheers,
Mauro
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