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

[Dmitry Osipenko <dmitry.osipenko@collabora.com>]

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@60p.
> 
> In general, it often a challenge to get 4k@60p properly with any of
> these small board devices. 4k@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@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.

-- 
Best regards,
Dmitry