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

[Ilia Mirkin]

On Fri, Jan 27, 2017 at 5:18 PM, Jason Ekstrand <jason at jlekstrand.net> 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.

Not sure what all these tables affect, but I've had no end of trouble
from nouveau supporting BGRA4 sampling but not rendering - the latest
fail is doing a copy image from a "BGRA4" renderbuffer (which gets
upgraded to RGBA8) and a BGRA4 texture. But also (buggy) applications
get weirded out by being unable to render to a fb with a BGRA4 texture
attachment.

  -ilia