Re: [PATCH] drm/udl: Add ARGB8888 as a format

From: Thomas Zimmermann
Date: Wed Mar 06 2024 - 07:07:16 EST


Hi,

sorry that I did not see the patch before.

Am 27.02.24 um 23:19 schrieb Douglas Anderson:
Even though the UDL driver converts to RGB565 internally (see
pixel32_to_be16() in udl_transfer.c), it advertises XRGB8888 for
compatibility. Let's add ARGB8888 to that list.

We had a heated discussion about the emulation of color formats. It was decided that XRGB8888 is the only format to support; and that's only because legacy userspace sometimes expects it. Adding other formats to the list should not be done easily.


This makes UDL devices work on ChromeOS again after commit
c91acda3a380 ("drm/gem: Check for valid formats"). Prior to that
commit things were "working" because we'd silently treat the ARGB8888
that ChromeOS wanted as XRGB8888.

This problem has been caused by userspace. Why can it not be fixed there?

And udl is just one driver. Any other driver without ARGB8888, such as simpledrm or ofdrm, would be affected. Do these work?

Best regards
Thomas


Fixes: c91acda3a380 ("drm/gem: Check for valid formats")
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---

drivers/gpu/drm/udl/udl_modeset.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
index 7702359c90c2..0f8d3678770e 100644
--- a/drivers/gpu/drm/udl/udl_modeset.c
+++ b/drivers/gpu/drm/udl/udl_modeset.c
@@ -253,6 +253,7 @@ static int udl_handle_damage(struct drm_framebuffer *fb,
static const uint32_t udl_primary_plane_formats[] = {
DRM_FORMAT_RGB565,
DRM_FORMAT_XRGB8888,
+ DRM_FORMAT_ARGB8888,
};
static const uint64_t udl_primary_plane_fmtmods[] = {

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)