Re: [PATCH v4 2/2] drm: Add HDMI 2.0 VIC support for AVI info-frames

[Jose Abreu <Jose.Abreu@synopsys.com>]

Hi Shashank,


On 23-03-2017 16:08, Sharma, Shashank wrote:
> Regards
>
> Shashank
>
>
> On 3/23/2017 5:57 PM, Jose Abreu wrote:
>> Hi Ville,
>>
>>
>> On 23-03-2017 15:45, Ville Syrjälä wrote:
>>> On Thu, Mar 23, 2017 at 03:28:29PM +0000, Jose Abreu wrote:
>>>> Hi Shashank,
>>>>
>>>>
>>>> On 23-03-2017 15:14, Shashank Sharma wrote:
>>>>> HDMI 1.4b support the CEA video modes as per range of
>>>>> CEA-861-D (VIC 1-64).
>>>>> For any other mode, the VIC filed in AVI infoframes should
>>>>> be 0.
>>>>> HDMI 2.0 sinks, support video modes range as per CEA-861-F
>>>>> spec, which is
>>>>> extended to (VIC 1-107).
>>>>>
>>>>> This patch adds a bool input variable, which indicates if
>>>>> the connected
>>>>> sink is a HDMI 2.0 sink or not. This will make sure that we
>>>>> don't pass a
>>>>> HDMI 2.0 VIC to a HDMI 1.4 sink.
>>>>>
>>>>> This patch touches all drm drivers, who are callers of this
>>>>> function
>>>>> drm_hdmi_avi_infoframe_from_display_mode but to make sure
>>>>> there is
>>>>> no change in current behavior, is_hdmi2 is kept as false.
>>>>>
>>>>> In case of I915 driver, this patch checks the
>>>>> connector->display_info
>>>>> to check if the connected display is HDMI 2.0.
>>>>>
>>>>> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
>>>>> Cc: Jose Abreu <jose.abreu@synopsys.com>
>>>>> Cc: Andrzej Hajda <a.hajda@samsung.com>
>>>>> Cc: Alex Deucher <alexander.deucher@amd.com>
>>>>> Cc: Daniel Vetter <daniel.vetter@intel.com>
>>>>>
>>>>> PS: This patch touches a few lines in few files, which were
>>>>> already above 80 char, so checkpatch gives 80 char warning
>>>>> again.
>>>>> - gpu/drm/omapdrm/omap_encoder.c
>>>>> - gpu/drm/i915/intel_sdvo.c
>>>>>
>>>>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>>>>> ---
>>>>>   drivers/gpu/drm/amd/amdgpu/dce_v10_0.c    |  2 +-
>>>>>   drivers/gpu/drm/amd/amdgpu/dce_v11_0.c    |  2 +-
>>>>>   drivers/gpu/drm/amd/amdgpu/dce_v8_0.c     |  2 +-
>>>>>   drivers/gpu/drm/bridge/analogix-anx78xx.c |  3 ++-
>>>>>   drivers/gpu/drm/bridge/sii902x.c          |  2 +-
>>>>>   drivers/gpu/drm/bridge/synopsys/dw-hdmi.c |  2 +-
>>>>>   drivers/gpu/drm/drm_edid.c                | 12 +++++++++++-
>>>>>   drivers/gpu/drm/exynos/exynos_hdmi.c      |  2 +-
>>>>>   drivers/gpu/drm/i2c/tda998x_drv.c         |  2 +-
>>>>>   drivers/gpu/drm/i915/intel_hdmi.c         |  5 ++++-
>>>>>   drivers/gpu/drm/i915/intel_sdvo.c         |  3 ++-
>>>>>   drivers/gpu/drm/mediatek/mtk_hdmi.c       |  2 +-
>>>>>   drivers/gpu/drm/omapdrm/omap_encoder.c    |  3 ++-
>>>>>   drivers/gpu/drm/radeon/radeon_audio.c     |  2 +-
>>>>>   drivers/gpu/drm/rockchip/inno_hdmi.c      |  2 +-
>>>>>   drivers/gpu/drm/sti/sti_hdmi.c            |  2 +-
>>>>>   drivers/gpu/drm/tegra/hdmi.c              |  2 +-
>>>>>   drivers/gpu/drm/tegra/sor.c               |  2 +-
>>>>>   drivers/gpu/drm/vc4/vc4_hdmi.c            |  2 +-
>>>>>   drivers/gpu/drm/zte/zx_hdmi.c             |  2 +-
>>>>>   include/drm/drm_edid.h                    |  3 ++-
>>>>>   21 files changed, 38 insertions(+), 21 deletions(-)
>>>>>
>>>> [snip]
>>>>
>>>>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>>>>> b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>>>>> index af93f7a..5ff2886 100644
>>>>> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>>>>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
>>>>> @@ -1146,7 +1146,7 @@ static void hdmi_config_AVI(struct
>>>>> dw_hdmi *hdmi, struct drm_display_mode *mode)
>>>>>       u8 val;
>>>>>         /* Initialise info frame from DRM mode */
>>>>> -    drm_hdmi_avi_infoframe_from_display_mode(&frame, mode);
>>>>> +    drm_hdmi_avi_infoframe_from_display_mode(&frame, mode,
>>>>> false);
>>>>>         if (hdmi->hdmi_data.enc_out_format == YCBCR444)
>>>>>           frame.colorspace = HDMI_COLORSPACE_YUV444;
>>>>>
>>>> dw-hdmi controller has full support for HDMI 2.0 features.
>>>> It all
>>>> depends on the platform it is integrated.
>>>>
>>>> I think adding a parameter to
>>>> drm_hdmi_avi_infoframe_from_display_mode is not the best idea
>>>> because of this case: A bridge can have support for HDMI 2.0
>>>> features but the platform may limit this support. I guess it
>>>> can
>>>> happen in other drivers too.
>>> Your driver is in full control of what gets passed here. So I
>>> don't see
>>> why that would be a problem.
>>>
>>> Also this doesn't really have anything to do with the
>>> capabilities of
>>> the source. All we want to make sure is that we don't send a
>>> VIC the
>>> sink will not understand.
>>>
>> But the driver is not aware of the platform limitations, its
>> generic to the controller only. We could add a field in pdata
>> which tells if platform is HDMI 2.0+ but what about other bridge
>> drivers or HDMI drivers? They will have to replicate the same
>> thing also.
>>
>> Best regards,
>> Jose Miguel Abreu
> I think the driver would be aware of the platform's
> capabilities, isn't it ?
> Else how would it even decide which mode to allow, and which to
> reject ?

The DRM core propagates the mode to the chain of configuration
before reaching the bridge driver also, there is a callback
supplied by pdata (mode_valid) which can check if the mode is
valid. (see
https://cgit.freedesktop.org/~airlied/linux/tree/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c?h=drm-next#n1740)

Best regards,
Jose Miguel Abreu


>
> Regards
> Shashank

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