Re: [PATCH v3 00/19] drm: starfive: jh7110: Enable display subsystem

[Michal Wilczynski]

On 9/6/26 05:55, Dominique Belhachemi wrote:
> On Sat, Sep 5, 2026 at 1:21 AM Maud Spierings <maud_spierings@xxxxxxxxx>
> wrote:
> 
>> Hello Michal,
>>
>> This new version added some more issues on my fml13v01 board, this time
>> 2 registers in the VOUT_CRG are misconfigured that were correct in v2,
>> namely:
>>
>> 0x295c0004 was 0x00000004 on the previous version but is now 0x00000006
>> 0x295c001c was 0x81000000 on the previous version but is now 0x80000000
>>
>> xx04 sets a slightly different clock divider, but it doesn't seem to
>> matter, display also works with this changed value.
>>
>> xx1c seems to select the wrong clock mux?
>>
>> After correcting 0x295c001c (and the ones that I mentioned before in the
>> hdmitx block), the display comes to life again.
>>
>> Not sure why these are changed.
>>
>> Same here on a VisionFive 2. The dc8200_pix0 mux register (0x295c001c)
> comes up 0x80000000 instead of 0x81000000 (which selects hdmitx0_pixelclk
> from the PHY).
> 
> v3 added CLK_SET_RATE_NO_REPARENT to stop clk_set_rate() from silently
> switching which clock feeds the display, but nothing then assigns the
> parent,
> so it is left on whatever the bootloader selected.
> 
> You could pin the two pixel-clock muxes to the HDMI PHY, is that acceptable?
> 
> dc8200: display@29400000 {
>   +                             assigned-clocks = <&voutcrg
> JH7110_VOUTCLK_DC8200_PIX0>,
>   +                                               <&voutcrg
> JH7110_VOUTCLK_DC8200_PIX1>;
>   +                             assigned-clock-parents = <&hdmi_phy>,
> <&hdmi_phy>;
> };
> 
> I tested this on the vf2.

Thank you Maud and Dominique,


I've tested this as well and it does seem like a good fix, will include
this in a v4.

> 
> Best
> -Dominique
> 

Best regards,
-- 
Michal Wilczynski <m.wilczynski@xxxxxxxxxxx>