On Wed, Mar 6, 2024 at 4:18 AM Thomas Zimmermann <tzimmerm...@suse.de> wrote:
>
> 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.
OTOH it is fixing a kernel change that broke userspace
> >
> > 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?
Probably any driver where ARGB8888 is equivalent to XRGB8888 (ie.
single primary plane, etc) should advertise both.
BR,
-R
> Best regards
> Thomas
>
> >
> > Fixes: c91acda3a380 ("drm/gem: Check for valid formats")
> > Signed-off-by: Douglas Anderson <diand...@chromium.org>
> > ---
> >
> > 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)
>
