[Mesa-dev] [PATCH 2/2] isl/formats: Only advertise sampling for A4B4G4R4 on Broadwell

[Kenneth Graunke]

On Friday, January 27, 2017 2:18:35 PM PST Jason Ekstrand wrote:
> This causes hangs on Broadwell if you try to render to it.  I have no
> idea how we managed to not hit this earlier.
> 
> Cc: "13.0 17.0" <mesa-stable at lists.freedesktop.org>
> ---
>  src/intel/isl/isl_format.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/src/intel/isl/isl_format.c b/src/intel/isl/isl_format.c
> index c8daece..bc157d5 100644
> --- a/src/intel/isl/isl_format.c
> +++ b/src/intel/isl/isl_format.c
> @@ -218,9 +218,10 @@ static const struct surface_format_info format_info[] = {
>     SF(50, 50,  x,  x,  x,  x,  x,  x,  x,    x,   P8A8_UNORM_PALETTE1)
>     SF( x,  x,  x,  x,  x,  x,  x,  x,  x,    x,   A1B5G5R5_UNORM)
>     /* According to the PRM, A4B4G4R4_UNORM isn't supported until Sky Lake
> -    * but empirical testing indicates that it works just fine on Broadwell.
> +    * but empirical testing indicates that at least sampling works just fine
> +    * on Broadwell.
>      */
> -   SF(80, 80,  x,  x, 80,  x,  x,  x,  x,    x,   A4B4G4R4_UNORM)
> +   SF(80, 80,  x,  x, 90,  x,  x,  x,  x,    x,   A4B4G4R4_UNORM)
>     SF(90,  x,  x,  x,  x,  x,  x,  x,  x,    x,   L8A8_UINT)
>     SF(90,  x,  x,  x,  x,  x,  x,  x,  x,    x,   L8A8_SINT)
>     SF( Y,  Y,  x, 45,  Y,  Y,  Y,  x,  x,    x,   R8_UNORM)
> 

Still somewhat grumpy that there are mandatory 4-bit formats that
aren't supported in hardware.  We definitely don't want to advertise
rendering to this if it doesn't work.

You can always do your clever hacks in BLORP to make it work for e.g.
copyimage etc, like you did for RGB9E5 and friends.

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
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