[PATCH v13 0/6] Add Synopsys DesignWare HDMI RX Controller

[Tim Surber]

Hi,

so the 4:4:4 issue was just a gstreamer bug and it worked when I applied 
an experimental fix [1].

So everything works for me using the default EDID now.

Tested-by: Tim Surber <me at timsurber.de>

[1]: 
https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8534

On 3/5/25 10:09, Dmitry Osipenko wrote:
> On 3/5/25 12:03, Dmitry Osipenko wrote:
>> On 3/5/25 11:10, Hans Verkuil wrote:
>>> On 05/03/2025 01:59, Tim Surber wrote:
>>>> Hi Dmitry,
>>>>
>>>> I did some more testing. That the Apple TV did not work was a bit
>>>> misleading.
>>>>
>>>> It was just, that the Apple TV defaulted to 4:4:4 Chroma which does not
>>>> work at all for me. (The same happens using the vendor driver).
>>>>
>>>> When I changed the EDID to match the vendor driver the HDMI handshake
>>>> happened with 4:2:0 chroma, where I could verify even 4k60fps using your
>>>> driver, nice!
>>>>
>>>> So the remaining problems I see are:
>>>> - 4:4:4 chroma not working in any resolution
>>>> - 4:2:2 and RGB not working in 4k60fps (is this a hardware limitation?)
>>>>
>>>> A possible workaround could be to disable these non supported formats in
>>>> the default EDID.
>>> I would like to merge this driver this week, since otherwise it will likely
>>> slip to v6.16. So if there is a working EDID, perhaps it can be used for now,
>>> and later on it can be patched if there is a better EDID.
>>>
>>> Would this EDID work? Tim, can you try this?
>>>
>>> v4l2-ctl --set-edid type=hdmi-4k-600mhz,ycbcr444,ycbcr422
>>>
>>> Alternatively, if there is indeed a HW limitation that prevents 4kp60 to work,
>>> try this:
>>>
>>> v4l2-ctl --set-edid type=hdmi-4k-300mhz,ycbcr444,ycbcr422
>>>
>>> Whichever of the two works is what we can use as default EDID.
>>
>> Disabling 444 and 422 is an option. Though, they work on my setup at
>> 4k at 60p.
>>
>> In general, it often a challenge to get 4k at 60p properly with any of
>> these small board devices. 4k at 60p works only using a short HDMI cable
>> for me. Also, not everyone aware that the micro HDMI adapter needs to be
>> compliant with HDMI 2.0 for 4k at 60, that's why 300MHz is the default.
>>
>> Will be nice to have the good EDID enabled by default in the defconfig.
>> Dealing with problems like that will be a headache for majority of
>> people, IMO.
> 
> BTW, I don't see it as a blocker. Driver works in general, new issues
> can be resolved with additional patches.
>