[PATCH 4/5] r600g, radeonsi: Use write-combined persistent GTT mappings

[Marek Olšák]

The resource flags actually tell you what you can do. If the COHERENT
flag is set, the mapping must be cached. If it's unset, it's up to
you.

If write-combining is faster for vertex uploads, then Glamor shouldn't
set the coherent flag.

Marek

On Thu, Jul 17, 2014 at 12:01 PM, Michel Dänzer <michel at daenzer.net> wrote:
> From: Michel Dänzer <michel.daenzer at amd.com>
>
> This is hopefully safe: The kernel makes sure writes to these mappings
> finish before the GPU might start reading from them, and the GPU caches
> are invalidated at the start of a command stream.
>
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
> ---
>  src/gallium/drivers/radeon/r600_buffer_common.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/gallium/drivers/radeon/r600_buffer_common.c b/src/gallium/drivers/radeon/r600_buffer_common.c
> index 40917f0..c8a0723 100644
> --- a/src/gallium/drivers/radeon/r600_buffer_common.c
> +++ b/src/gallium/drivers/radeon/r600_buffer_common.c
> @@ -131,7 +131,7 @@ bool r600_init_resource(struct r600_common_screen *rscreen,
>             res->b.b.flags & (PIPE_RESOURCE_FLAG_MAP_PERSISTENT |
>                               PIPE_RESOURCE_FLAG_MAP_COHERENT)) {
>                 res->domains = RADEON_DOMAIN_GTT;
> -               flags = 0;
> +               flags = RADEON_FLAG_GTT_WC;
>         }
>
>         /* Tiled textures are unmappable. Always put them in VRAM. */
> --
> 2.0.0
>
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