[Mesa-dev] [PATCH 1/2] i965: Apply depthstencil alignment workaround when doing fast clears.

[Eric Anholt]

Paul Berry <stereotype441 at gmail.com> writes:

> Fast depth clears have the same depth/stencil alignment requirements
> as other drawing operations.  Therefore, we need to call
> brw_workaround_depthstencil_alignment() from both the clear and
> drawing paths.
>
> Without this fix, we get image corruption if the following conditions
> hold: (a) the first ever drawing operation to a depth miplevel (or the
> first drawing operation after having used the texture for sampling) is
> a clear, (b) the depth miplevel has a size that is eligible for fast
> depth clears, and (c) the depth miplevel has an offset within the
> miptree that isn't 8x8 aligned.
>
> Fixes piglit "depthstencil-render-miplevels" tests with size 273.
>
> NOTE: This is a candidate for stable branches
> ---
>  src/mesa/drivers/dri/i965/brw_clear.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_clear.c b/src/mesa/drivers/dri/i965/brw_clear.c
> index 53d8e54..cde1a06 100644
> --- a/src/mesa/drivers/dri/i965/brw_clear.c
> +++ b/src/mesa/drivers/dri/i965/brw_clear.c
> @@ -40,6 +40,8 @@
>  #include "intel_mipmap_tree.h"
>  #include "intel_regions.h"
>  
> +#include "brw_context.h"
> +
>  #define FILE_DEBUG_FLAG DEBUG_BLIT
>  
>  static const char *buffer_names[] = {
> @@ -219,7 +221,8 @@ brw_fast_clear_depth(struct gl_context *ctx)
>  static void
>  brw_clear(struct gl_context *ctx, GLbitfield mask)
>  {
> -   struct intel_context *intel = intel_context(ctx);
> +   struct brw_context *brw = brw_context(ctx);
> +   struct intel_context *intel = &brw->intel;
>  
>     if (!_mesa_check_conditional_render(ctx))
>        return;
> @@ -229,6 +232,7 @@ brw_clear(struct gl_context *ctx, GLbitfield mask)
>     }
>  
>     intel_prepare_render(intel);
> +   brw_workaround_depthstencil_alignment(brw);

It seems like this should be happening in brw_fast_clear(), either
before before calling blorp or inside of it, instead of in the potential
caller of brw_fast_clear().  Makes sense, though.

>     if (mask & BUFFER_BIT_DEPTH) {
>        if (brw_fast_clear_depth(ctx)) {
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