[Mesa-dev] [PATCH] gbm/dri: Flush after unmap

[Eric Anholt]

Thomas Hellstrom <thellstrom at vmware.com> writes:

> Drivers may queue dma operations on the context at unmap time so we need
> to flush to make sure the data gets to the bo. Ideally the application
> would take care of this, but since there appears to be no exported gbm
> flush functionality we need to explicitly flush at unmap time.
>
> This fixes a problem where kmscube on vmwgfx in rgba textured mode would
> render using an uninitialized texture rather than the intended
> rgba pattern.
>
> Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
> ---
>  src/gbm/backends/dri/gbm_dri.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/src/gbm/backends/dri/gbm_dri.c b/src/gbm/backends/dri/gbm_dri.c
> index ac7ede8..6c2244c 100644
> --- a/src/gbm/backends/dri/gbm_dri.c
> +++ b/src/gbm/backends/dri/gbm_dri.c
> @@ -243,7 +243,7 @@ struct dri_extension_match {
>  };
>  
>  static struct dri_extension_match dri_core_extensions[] = {
> -   { __DRI2_FLUSH, 1, offsetof(struct gbm_dri_device, flush) },
> +   { __DRI2_FLUSH, 4, offsetof(struct gbm_dri_device, flush) },
>     { __DRI_IMAGE, 1, offsetof(struct gbm_dri_device, image) },
>     { __DRI2_FENCE, 1, offsetof(struct gbm_dri_device, fence), 1 },
>     { __DRI2_INTEROP, 1, offsetof(struct gbm_dri_device, interop), 1 },
> @@ -992,6 +992,13 @@ gbm_dri_bo_unmap(struct gbm_bo *_bo, void *map_data)
>        return;
>  
>     dri->image->unmapImage(dri->context, bo->image, map_data);
> +
> +   /*
> +    * Not all DRI drivers use direct maps. They may queue up DMA operations
> +    * on the mapping context. Since there is no explicit gbm flush
> +    * mechanism. We need to flush here.

With the following change:

s/mechanism. We/mechanism, we/

Reviewed-by: Eric Anholt <eric at anholt.net>

Reminder for anyone else looking at this patch: The context being
flushed here isn't some main GL context made by the app, it's this
little dummy context that was created internally in gbm so that these
kinds of GPU transfers could be done for the image mapping functions.

> +    */
> +   dri->flush->flush_with_flags(dri->context, NULL, __DRI2_FLUSH_CONTEXT, 0);
>  }
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 832 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20170328/121c0c60/attachment-0001.sig>