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

[Dmitry Osipenko]

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.

-- 
Best regards,
Dmitry