[Mesa-dev] EXT_shader_image_load_store requires format-less loads?

[Pelloux-prayer, Pierre-eric]

Hi Ilia,

Actually I wasn't sure that the PIPE_CAP_IMAGE_LOAD_FORMATTED was needed.
Your reasonning and your patch series make sense, thanks for fixing this.

Best,
Pierre-Eric

On 07/08/2019 02:10, Ilia Mirkin wrote:
> Hi Pierre-Eric,
> 
> I see you recently added EXT_shader_image_load_store - nice. It seems
> like you're relying on the format-less read access feature to make it
> happen:
> 
> +   extensions->EXT_shader_image_load_store &=
> +      screen->get_param(screen, PIPE_CAP_IMAGE_LOAD_FORMATTED);
> 
> Can you elaborate why this is necessary? From a quick read of the
> spec, it seems like the format is required, and maps to a format same
> way that ARB_image_load_store does (well, *slightly* different, but in
> the end, we get one of those same enum values out). The LOAD_FORMATTED
> thing enables you to read from an image with PIPE_FORMAT_NONE (which
> normally can only be written to).
> 
> I don't see anything in the spec which requires it, but perhaps I
> missed something. I'd be a bit surprised though, since this is rather
> non-trivial on NVIDIA GPUs.
> 
> Cheers,
> 
>   -ilia
>