[PATCH] drm: Introduce RGB 64-bit 16:16:16:16 float format

[PATCH] drm: Introduce RGB 64-bit 16:16:16:16 float format

[Tina Zhang]

This patch is from "[PATCH v19 0/6] drm/i915/gvt: Dma-buf support for GVT-g":
https://lists.freedesktop.org/archives/intel-gvt-dev/2017-November/002508.html

The RGB 64-bit 16:16:16:16 float pixel format is needed by some Apps in
windows. The float format in each component is 1:5:10 MSb-sign:exponent:
fraction.

This patch is to introduce the format to drm, so that the windows guest's
framebuffer in this kind of format can be recognized and used by linux
host.

Tina Zhang (1):
  drm: Introduce RGB 64-bit 16:16:16:16 float format

 include/uapi/drm/drm_fourcc.h | 4 ++++
 1 file changed, 4 insertions(+)

-- 
2.7.4

[PATCH] drm: Introduce RGB 64-bit 16:16:16:16 float format

[Tina Zhang]

The RGB 64-bit 16:16:16:16 float pixel format is needed by some Apps in
windows. The float format in each component is 1:5:10 MSb-sign:exponent:
fraction.

This patch is to introduce the format to drm, so that the windows guest's
framebuffer in this kind of format can be recognized and used by linux
host.

v14:
- add some details about the float pixel format. (Daniel)
- add F suffix to the defined name. (Daniel)

v12:
- send to dri-devel at lists.freedesktop.org. (Ville)

v9:
- separated from framebuffer decoder patch. (Zhenyu) (Xiaoguang)

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 include/uapi/drm/drm_fourcc.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index 3ad838d..391d2e6 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -113,6 +113,10 @@ extern "C" {
 
 #define DRM_FORMAT_AYUV		fourcc_code('A', 'Y', 'U', 'V') /* [31:0] A:Y:Cb:Cr 8:8:8:8 little endian */
 
+/* 64 bpp RGB 16:16:16:16 Floating Point */
+#define DRM_FORMAT_XRGB161616F  fourcc_code('X', 'R', '3', 'F') /* [63:0] x:R:G:B 16:16:16:16 little endian */
+#define DRM_FORMAT_XBGR161616F  fourcc_code('X', 'B', '3', 'F') /* [63:0] x:B:G:R 16:16:16:16 little endian */
+
 /*
  * 2 plane RGB + A
  * index 0 = RGB plane, same format as the corresponding non _A8 format has
-- 
2.7.4

Re: [PATCH] drm: Introduce RGB 64-bit 16:16:16:16 float format

[Ville Syrjälä]

On Thu, Nov 23, 2017 at 04:56:56PM +0800, Tina Zhang wrote:
> The RGB 64-bit 16:16:16:16 float pixel format is needed by some Apps in
> windows. The float format in each component is 1:5:10 MSb-sign:exponent:
> fraction.
> 
> This patch is to introduce the format to drm, so that the windows guest's
> framebuffer in this kind of format can be recognized and used by linux
> host.
> 
> v14:
> - add some details about the float pixel format. (Daniel)
> - add F suffix to the defined name. (Daniel)
> 
> v12:
> - send to dri-devel at lists.freedesktop.org. (Ville)
> 
> v9:
> - separated from framebuffer decoder patch. (Zhenyu) (Xiaoguang)
> 
> Signed-off-by: Tina Zhang <tina.zhang@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  include/uapi/drm/drm_fourcc.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> index 3ad838d..391d2e6 100644
> --- a/include/uapi/drm/drm_fourcc.h
> +++ b/include/uapi/drm/drm_fourcc.h
> @@ -113,6 +113,10 @@ extern "C" {
>  
>  #define DRM_FORMAT_AYUV		fourcc_code('A', 'Y', 'U', 'V') /* [31:0] A:Y:Cb:Cr 8:8:8:8 little endian */
>  
> +/* 64 bpp RGB 16:16:16:16 Floating Point */

As before this is still extremely vague. Stating that each component is
a IEEE-754 half-precision float (binary16) should cover it. Well, assuming
that it really is one.

> +#define DRM_FORMAT_XRGB161616F  fourcc_code('X', 'R', '3', 'F') /* [63:0] x:R:G:B 16:16:16:16 little endian */
> +#define DRM_FORMAT_XBGR161616F  fourcc_code('X', 'B', '3', 'F') /* [63:0] x:B:G:R 16:16:16:16 little endian */

Missing one 16 from that name to be consistent with the non-float stuff.

Also maybe it should be (... '4', 'F')? '3' would seem to imply a 48 bit
pixel.

And of course it's still missing the actual implemntation for any driver.

> +
>  /*
>   * 2 plane RGB + A
>   * index 0 = RGB plane, same format as the corresponding non _A8 format has
> -- 
> 2.7.4

-- 
Ville Syrjälä
Intel OTC