[PATCH 0/2] drm/rockchip: dw_hdmi: Add 4k at 30 support

[Andy Yan]

Hi Sascha:

On 8/24/22 15:07, Sascha Hauer wrote:
> Hi Andy Et al.,
>
> On Mon, Aug 22, 2022 at 05:20:15PM +0200, Sascha Hauer wrote:
>> This series adds support for 4k at 30 to the rockchip HDMI controller. This
>> has been tested on a rk3568 rock3a board. It should be possible to add
>> 4k at 60 support the same way, but it doesn't work for me, so let's add
>> 4k at 30 as a first step.
> I tried adding 4k at 60 support the same way, just by adding the missing
> fields for 600MHz in the PLL/phy settings. I get a picture on the
> screen, but it's not very stable: The monitor often gets black, scans
> through the different HDMI inputs and then syncs again. Also when I
> re-plug the cable while weston is running I won't get any picture
> anymore (the same works fine with lower resolutions). I also tried
> the Rock3a 4.19 Kernel which is based on the Rockchip Kernel and I saw
> similar problems there.
>
> Do you have an idea what could go wrong there?


4K HDMI output from hdmi need very carefully tuning  of HDMI PHY and PLL.

I can make sure that HDMI 4K output on rk3399/rk3288/rk356x are work 
fine with our

vendor kernel, but the upstream kernel is only can run at 1080p output, 
I have tested

on rk3399 and rk3568-evb1[0]


I am not  familiar with hdmi tuning, so I am sorry i can't give detail 
idea about this issue,

maybe a more carefully comparison with hdmi driver and pll 
configuration  between upstream kernel and rockchip 4.19 kernel?

I think you have rk356x evb board, do you have a detail test about 4K 
HDMI output with this board? If you have issue about 4k hdmi output

on this board with rockchip 4.19 kernel, we can help to figure it out.

Anyway, I loop Algea to the list, he is maintaining our hdmi 
development, but I am sorry to say that he is

also very busy😅

I don't have a rock3a, so I can't confirm the problem you described on 
4.19 kernel.




[0]https://patchwork.kernel.org/project/linux-rockchip/patch/20220225075150.2729401-16-s.hauer@pengutronix.de/



>
> Sascha
>
>