[PATCH] drm/fourcc: add LINEAR modifiers with an exact pitch alignment

[Marek Olšák]

Only for you: Attached.

Marek

On Sun, Dec 15, 2024 at 6:37 PM Joshua Ashton <joshua at froggi.es> wrote:

> You should just re-send the whole patch, probably.
>
> On 12/15/24 8:54 PM, Marek Olšák wrote:
> > Missed 2 lines from the diff:
> >
> > +#define DRM_FORMAT_MOD_LINEAR_PITCH_ALIGN_128B fourcc_mod_code(NONE, 2)
> > +#define DRM_FORMAT_MOD_LINEAR_PITCH_ALIGN_256B fourcc_mod_code(NONE, 3)
> >
> > Marek
> >
> > On Sun, Dec 15, 2024 at 3:53 PM Marek Olšák <maraeo at gmail.com
> > <mailto:maraeo at gmail.com>> wrote:
> >
> >     The comment explains the problem with DRM_FORMAT_MOD_LINEAR.
> >
> >     Signed-off-by: Marek Olšák <marek.olsak at amd.com
> >     <mailto:marek.olsak at amd.com>>
> >
> >     diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/
> >     drm_fourcc.h
> >     index 78abd819fd62e..8ec4163429014 100644
> >     --- a/include/uapi/drm/drm_fourcc.h
> >     +++ b/include/uapi/drm/drm_fourcc.h
> >     @@ -484,9 +484,27 @@ extern "C" {
> >        * modifier (e.g. not setting DRM_MODE_FB_MODIFIERS in the
> >     DRM_ADDFB2 ioctl),
> >        * which tells the driver to also take driver-internal information
> >     into account
> >        * and so might actually result in a tiled framebuffer.
> >     + *
> >     + * WARNING:
> >     + * There are drivers out there that expose DRM_FORMAT_MOD_LINEAR,
> >     but only
> >     + * support a certain pitch alignment and can't import images with
> >     this modifier
> >     + * if the pitch alignment isn't exactly the one supported. They can
> >     however
> >     + * allocate images with this modifier and other drivers can import
> >     them only
> >     + * if they support the same pitch alignment. Thus,
> >     DRM_FORMAT_MOD_LINEAR is
> >     + * fundamentically incompatible across devices and is the only
> >     modifier that
> >     + * has a chance of not working. The PITCH_ALIGN modifiers should be
> >     used
> >     + * instead.
> >        */
> >       #define DRM_FORMAT_MOD_LINEAR  fourcc_mod_code(NONE, 0)
> >
> >     +/* Linear layout modifiers with an explicit pitch alignment in
> bytes.
> >     + * Exposing this modifier requires that the pitch alignment is
> exactly
> >     + * the number in the definition.
> >     + */
> >     +#define DRM_FORMAT_MOD_LINEAR_PITCH_ALIGN_64B fourcc_mod_code(NONE,
> 1)
> >
>
> - Joshie 🐸✨
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/amd-gfx/attachments/20241215/f070c828/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-drm-fourcc-add-LINEAR-modifiers-with-an-exact-pitch-.patch
Type: text/x-patch
Size: 2098 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/amd-gfx/attachments/20241215/f070c828/attachment-0001.bin>