[Mesa-dev] [PATCH 05/17] gallium: reserve one shader buffer for shared storage

[Marek Olšák]

I don't understand this. Can you explain it?

AFAIK, shared variables don't need a backing buffer.

Thanks,
Marek

On Sun, Jan 24, 2016 at 10:09 PM, Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
> At least, one shader buffer must be available for compute shaders.
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>  src/gallium/include/pipe/p_state.h     | 2 +-
>  src/mesa/state_tracker/st_extensions.c | 6 ++++--
>  2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/src/gallium/include/pipe/p_state.h b/src/gallium/include/pipe/p_state.h
> index 2e4d283..051856e 100644
> --- a/src/gallium/include/pipe/p_state.h
> +++ b/src/gallium/include/pipe/p_state.h
> @@ -61,7 +61,7 @@ extern "C" {
>  #define PIPE_MAX_SHADER_INPUTS    80 /* 32 GENERIC + 32 PATCH + 16 others */
>  #define PIPE_MAX_SHADER_OUTPUTS   80 /* 32 GENERIC + 32 PATCH + 16 others */
>  #define PIPE_MAX_SHADER_SAMPLER_VIEWS 32
> -#define PIPE_MAX_SHADER_BUFFERS   32
> +#define PIPE_MAX_SHADER_BUFFERS   33
>  #define PIPE_MAX_SHADER_IMAGES    32
>  #define PIPE_MAX_TEXTURE_LEVELS   16
>  #define PIPE_MAX_SO_BUFFERS        4
> diff --git a/src/mesa/state_tracker/st_extensions.c b/src/mesa/state_tracker/st_extensions.c
> index d066784..c198892 100644
> --- a/src/mesa/state_tracker/st_extensions.c
> +++ b/src/mesa/state_tracker/st_extensions.c
> @@ -219,8 +219,10 @@ void st_init_limits(struct pipe_screen *screen,
>                                            pc->MaxUniformBlocks);
>
>        pc->MaxAtomicCounters = MAX_ATOMIC_COUNTERS;
> -      pc->MaxAtomicBuffers = screen->get_shader_param(
> -            screen, sh, PIPE_SHADER_CAP_MAX_SHADER_BUFFERS) / 2;
> +      pc->MaxAtomicBuffers =
> +         _clamp(screen->get_shader_param(screen, sh,
> +                                         PIPE_SHADER_CAP_MAX_SHADER_BUFFERS),
> +                0, PIPE_MAX_SHADER_BUFFERS - 1) / 2;
>        pc->MaxShaderStorageBlocks = pc->MaxAtomicBuffers;
>
>        /* Gallium doesn't really care about local vs. env parameters so use the
> --
> 2.6.4
>
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