Re: [PATCH 0/2] drm: xlnx: zynqmp_kms: 16 bpp fixes for Xorg startup on AMD KV260

[Mikko Rapeli <mikko.rapeli@linaro.org>]

Hi,

On Fri, Dec 19, 2025 at 02:30:11PM +0200, Mikko Rapeli wrote:
> On Fri, Dec 19, 2025 at 01:59:14PM +0200, Tomi Valkeinen wrote:
> > On 05/12/2025 14:37, Mikko Rapeli wrote:
> > > Currently on default yocto images Xorg fails to start on AMD KV260
> > > because 24/32 color depth gets detected but does not actually work.
> > > 
> > > These two patches fix the issue and now 16 bpp gets detected
> > > and Xorg starts and draws on external HDMI display using
> > > kernel.org based linux-yocto kernel.
> > > 
> > > Anatoliy Klymenko (1):
> > >   drm: xlnx: zynqmp_kms: Init fbdev with 16 bit color
> > > 
> > > Mikko Rapeli (1):
> > >   drm: xlnx: zynqmp_kms: set preferred_depth to 16 bpp
> > > 
> > >  drivers/gpu/drm/xlnx/zynqmp_kms.c | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > 
> > 
> > Did you notice the few already sent serieses on the list where the topic
> > has been discussed?
> 
> > [PATCH] drm: xlnx: zynqmp_dp: Support DRM_FORMAT_XRGB8888
> > [PATCH 0/3] drm: zynqmp: Make the video plane primary
> 
> Oh I wasn't aware of these.
> 
> > Or is there something else on KV260 that messes up the 24 bit color?
> 
> These look very similar and likely fix the X11 startup. I will give them
> a try.

Right, now I've tested:

 * these patches from Anatoliy and me to help X11 use 16bpp mode by default
   and removes the need to manually setup Xorg for 16bpp
 * "drm: xlnx: zynqmp_dp: Support DRM_FORMAT_XRGB8888" which enables the X11 default
   24bpp to work, no need to set Xorg config to 16bpp
 * "drm: zynqmp: Make the video plane primary" which also fixes the X11 default
   24bpp to work, no need to set Xorg config to 16bpp

All of these fix HDMI graphics output on AMD KV260 board with yocto genericarm64 machine
and core-image-sato image which includes Xorg. The graphics rendering is still
very slow but I think that is a different problem.

I guess the last series from Sean Anderson is moving forward so I'll
reply to that thread separately.

Tested-by: Mikko Rapeli <mikko.rapeli@linaro.org>

Cheers,
-Mikko