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

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Message-ID: <5f570a3b-7bee-43e0-9a36-3d106984fec6@suse.de>
Date: Tue, 6 Jan 2026 08:41:37 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Mikko Rapeli <mikko.rapeli@...aro.org>,
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org,
 Laurent Pinchart <laurent.pinchart@...asonboard.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Michal Simek <michal.simek@....com>,
 Bill Mills <bill.mills@...aro.org>,
 Ilias Apalodimas <ilias.apalodimas@...aro.org>
Subject: Re: [PATCH 0/2] drm: xlnx: zynqmp_kms: 16 bpp fixes for Xorg startup
 on AMD KV260

Hi

Am 22.12.25 um 09:58 schrieb Mikko Rapeli:
> 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.

Just want to say that the series here improves xlnx and makes it a 
'better' driver. IMHO the changes should be merged independently from 
what happens with the other series.

Best regards
Thomas

>
> Tested-by: Mikko Rapeli <mikko.rapeli@...aro.org>
>
> Cheers,
> -Mikko

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)