[Intel-gfx] [PATCH v13 2/7] drm: Introduce RGB 64-bit 16:16:16:16 float format

[Zhang, Tina]

> -----Original Message-----
> From: Daniel Vetter [mailto:daniel.vetter at ffwll.ch] On Behalf Of Daniel Vetter
> Sent: Tuesday, August 15, 2017 10:50 PM
> To: Zhang, Tina <tina.zhang at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; intel-gvt-dev at lists.freedesktop.org; dri-
> devel at lists.freedesktop.org; ville.syrjala at linux.intel.com;
> zhenyuw at linux.intel.com; Lv, Zhiyuan <zhiyuan.lv at intel.com>; Wang, Zhi A
> <zhi.a.wang at intel.com>; alex.williamson at redhat.com; kraxel at redhat.com;
> chris at chris-wilson.co.uk; daniel at ffwll.ch; kwankhede at nvidia.com; Tian, Kevin
> <kevin.tian at intel.com>; Chen, Xiaoguang <xiaoguang.chen at intel.com>
> Subject: Re: [PATCH v13 2/7] drm: Introduce RGB 64-bit 16:16:16:16 float
> format
> 
> On Tue, Jul 25, 2017 at 05:28:15PM +0800, Tina Zhang wrote:
> > The RGB 64-bit 16:16:16:16 float pixel format is needed by windows
> > guest VM. This patch is to introduce the format to drm.
> >
> > v1:
> > Suggested by Ville to submit this patch to dri-devel.
> >
> > Signed-off-by: Xiaoguang Chen <xiaoguang.chen at intel.com>
> > Signed-off-by: Tina Zhang <tina.zhang at intel.com>
> > ---
> >  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 7586c46..3e002e3 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 */
> > +#define DRM_FORMAT_XRGB161616  fourcc_code('X', 'R', '4', '8') /*
> > +[63:0] x:R:G:B 16:16:16:16 little endian */ #define
> > +DRM_FORMAT_XBGR161616  fourcc_code('X', 'B', '4', '8') /* [63:0]
> > +x:B:G:R 16:16:16:16 little endian */
> 
> I think the comment should go a bit more into detail what the float format is
> supposed to look like. And I think we should have a F or _FLOAT suffix to the
> defined name, since the same layout could also work for integers (and some hw
> somewhere probably has that. Maybe also put that F into the last slot of the
> fourcc.
Thanks. I prefer to add F and also put F into the last slot of the fourcc. 
I'm not sure about the code rule. Does it make sense?
#define	DRM_FORMAT_XRGB161616F fourcc_code('X', 'R', '3', 'F')
Where '3' stands for the three fields (R, G, B) without Alpha.

BR,
Tina
> -Daniel
> > +
> >  /*
> >   * 2 plane RGB + A
> >   * index 0 = RGB plane, same format as the corresponding non _A8
> > format has
> > --
> > 2.7.4
> >
> 
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch