[PATCH 1/5] drm/fourcc: Add 16 bpc fixed point framebuffer formats.

[Mario Kleiner]

On Fri, Mar 19, 2021 at 10:16 PM Ville Syrjälä
<ville.syrjala at linux.intel.com> wrote:
>
> On Fri, Mar 19, 2021 at 10:03:13PM +0100, Mario Kleiner wrote:
> > These are 16 bits per color channel unsigned normalized formats.
> > They are supported by at least AMD display hw, and suitable for
> > direct scanout of Vulkan swapchain images in the format
> > VK_FORMAT_R16G16B16A16_UNORM.
> >
> > Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
> > ---
> >  drivers/gpu/drm/drm_fourcc.c  | 4 ++++
> >  include/uapi/drm/drm_fourcc.h | 7 +++++++
> >  2 files changed, 11 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> > index 03262472059c..ce13d2be5d7b 100644
> > --- a/drivers/gpu/drm/drm_fourcc.c
> > +++ b/drivers/gpu/drm/drm_fourcc.c
> > @@ -203,6 +203,10 @@ const struct drm_format_info *__drm_format_info(u32 format)
> >               { .format = DRM_FORMAT_ARGB16161616F,   .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> >               { .format = DRM_FORMAT_ABGR16161616F,   .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> >               { .format = DRM_FORMAT_AXBXGXRX106106106106, .depth = 0, .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> > +             { .format = DRM_FORMAT_XRGB16161616,    .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1 },
> > +             { .format = DRM_FORMAT_XBGR16161616,    .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1 },
> > +             { .format = DRM_FORMAT_ARGB16161616,    .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> > +             { .format = DRM_FORMAT_ABGR16161616,    .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> >               { .format = DRM_FORMAT_RGB888_A8,       .depth = 32, .num_planes = 2, .cpp = { 3, 1, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> >               { .format = DRM_FORMAT_BGR888_A8,       .depth = 32, .num_planes = 2, .cpp = { 3, 1, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> >               { .format = DRM_FORMAT_XRGB8888_A8,     .depth = 32, .num_planes = 2, .cpp = { 4, 1, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true },
> > diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> > index f76de49c768f..f7156322aba5 100644
> > --- a/include/uapi/drm/drm_fourcc.h
> > +++ b/include/uapi/drm/drm_fourcc.h
> > @@ -168,6 +168,13 @@ extern "C" {
> >  #define DRM_FORMAT_RGBA1010102       fourcc_code('R', 'A', '3', '0') /* [31:0] R:G:B:A 10:10:10:2 little endian */
> >  #define DRM_FORMAT_BGRA1010102       fourcc_code('B', 'A', '3', '0') /* [31:0] B:G:R:A 10:10:10:2 little endian */
> >
> > +/* 64 bpp RGB */
> > +#define DRM_FORMAT_XRGB16161616      fourcc_code('X', 'R', '4', '8') /* [63:0] x:R:G:B 16:16:16:16 little endian */
> > +#define DRM_FORMAT_XBGR16161616      fourcc_code('X', 'B', '4', '8') /* [63:0] x:B:G:R 16:16:16:16 little endian */
> > +
> > +#define DRM_FORMAT_ARGB16161616      fourcc_code('A', 'R', '4', '8') /* [63:0] A:R:G:B 16:16:16:16 little endian */
> > +#define DRM_FORMAT_ABGR16161616      fourcc_code('A', 'B', '4', '8') /* [63:0] A:B:G:R 16:16:16:16 little endian */
>
> These look reasonable enough to me. IIRC we should be able to expose
> them on some recent Intel hw as well.
>
> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
>

Thanks Ville!

Indeed i looked over the Intel PRM's, and while fp16 support seems to
be rather recent (Gen8? Gen9? Gen10? Can't remember atm.), iirc, I
found references to rgb16 fixed point back to gen5 / Ironlake. That
would be pretty cool! The precision limit for the encoders on Intel is
also 12 bpc atm., right?

-mario

> --
> Ville Syrjälä
> Intel