[Intel-gfx] [PATCH 0/3] Support 64 bpp half float formats

[Ville Syrjälä]

On Wed, Nov 28, 2018 at 10:38:10PM -0800, Kevin Strasser wrote:
> This series defines new formats and adds a plane property to be used for
> floating point framebuffer content. Implementation is then added to i915.
> 
> I have shared an IGT branch which adds test coverage for the new formats:
>   https://github.com/strassek/xorg-intel-gpu-tools/tree/fp16

Looks about similar as what I had written. I wrote my half<->full
conversion thing from scratch which probably means it has more rounding
errors and whatnot. The speed of mine wasn't exactly stellar and looks
like your version probably has the same issue. So I was actually
thinking of using the sse<something> instructions meant for this
could provide a nice speedup. I guess we might want the pure c version
as a backup though. Hmm. Now I also seem to recall that I noticed
there being a compiler intrinsic even for single value half<->full
precision conversion. Did you look into using that (if I didn't imagine
it)?

BTW I just rebased my fp16 for pre-icl platforms:
git://github.com/vsyrjala/linux.git fp16_scanout_2

Apart from the ivb/hsw w/a there isn't all that much unexpected
when it comes to fp16 on those platforms either.

> 
> Kevin Strasser (3):
>   drm/fourcc: Add 64 bpp half float formats
>   drm: Add optional PIXEL_NORMALIZE_RANGE property to drm_plane
>   drm/i915: Implement half float formats and pixel normalize property
> 
>  drivers/gpu/drm/drm_atomic.c         |  2 +
>  drivers/gpu/drm/drm_atomic_uapi.c    |  4 ++
>  drivers/gpu/drm/drm_color_mgmt.c     | 67 +++++++++++++++++++++++
>  drivers/gpu/drm/drm_crtc_internal.h  |  1 +
>  drivers/gpu/drm/drm_fourcc.c         |  4 ++
>  drivers/gpu/drm/i915/i915_reg.h      | 15 ++++-
>  drivers/gpu/drm/i915/intel_display.c | 47 ++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h     |  5 ++
>  drivers/gpu/drm/i915/intel_sprite.c  | 82 ++++++++++++++++++++++++++--
>  include/drm/drm_color_mgmt.h         |  9 +++
>  include/drm/drm_fourcc.h             |  3 +
>  include/drm/drm_plane.h              | 14 +++++
>  include/uapi/drm/drm_fourcc.h        |  6 ++
>  13 files changed, 252 insertions(+), 7 deletions(-)
> 
> -- 
> 2.17.1
> 
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-- 
Ville Syrjälä
Intel