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

[Joshua Ashton]

Not really for my benefit, more that it's the proper thing to do if you 
want anyone to apply your patch.

You should really just be using git send-email.

On 12/15/24 11:57 PM, Marek Olšák wrote:
> Only for you: Attached.
> 
> Marek
> 
> On Sun, Dec 15, 2024 at 6:37 PM Joshua Ashton <joshua at froggi.es 
> <mailto: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>
>      > <mailto: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>
>      >     <mailto: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 🐸✨
> 

- Joshie 🐸✨