[Mesa-dev] [PATCH] meta: Remove dither bit from blit paths that do not need it

[Kenneth Graunke]

On Friday, August 01, 2014 08:37:53 PM Topi Pohjolainen wrote:
> Similarly to an older patch. This is the minimum needed to fix the
> bug but there are other meta-paths remaining that have the bit
> since its introduction but not before.

Why not just drop the

   _mesa_set_enable(ctx, GL_DITHER, GL_TRUE);

in _mesa_meta_begin(), which was introduced in commit 05b52efbc977311c96ba31ac5fa2c95fe525d85e?

Neil's new glClearTexSubImage path only wants it to be saved/restored so he can /disable/ it.  I see no reason to explicitly turn it /on/ for all paths...

That should fix the bug.

> 
> commit e526ebf35c113d59eb0b860e492c1308d3862ee9
> Author: Kenneth Graunke <kenneth at whitecape.org>
> Date:   Mon May 5 14:03:46 2014 -0700
> 
>     meta: Add a new MESA_META_DRAW_BUFFERS bit.
> 
>     This will be used for saving/restoring the glDrawBuffers state.
>     For now, make sure that existing users of MESA_META_ALL don't get
>     the new bit, since they probably won't want it.
> 
>     Cc: "10.2" <mesa-stable at lists.freedesktop.org>
>     Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
>     Reviewed-by: Anuj Phogat <anuj.phogat at gmail.com>
>     Reviewed-by: Eric Anholt <eric at anholt.net>

Quoting this commit message is a bit confusing - usually, when people quote other commits, it's referring to a regression...and the regression was from 05b52efbc977311c96ba31ac5fa2c95fe525d85e.  Masking off unnecessary save/restore bits is a pretty common thing to do.

> Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=81828.
> 
> Signed-off-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
> CC: Neil Roberts <neil at linux.intel.com>
> ---
>  src/mesa/drivers/common/meta.c      | 3 ++-
>  src/mesa/drivers/common/meta_blit.c | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/src/mesa/drivers/common/meta.c b/src/mesa/drivers/common/meta.c
> index 604bc21..b4f26d0 100644
> --- a/src/mesa/drivers/common/meta.c
> +++ b/src/mesa/drivers/common/meta.c
> @@ -2798,7 +2798,8 @@ copytexsubimage_using_blit_framebuffer(struct gl_context *ctx, GLuint dims,
>  
>     _mesa_unlock_texture(ctx, texObj);
>  
> -   _mesa_meta_begin(ctx, MESA_META_ALL & ~MESA_META_DRAW_BUFFERS);
> +   _mesa_meta_begin(ctx, MESA_META_ALL & ~(MESA_META_DRAW_BUFFERS |
> +                                           MESA_META_DITHER));
>  
>     _mesa_GenFramebuffers(1, &fbo);
>     _mesa_BindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo);
> diff --git a/src/mesa/drivers/common/meta_blit.c b/src/mesa/drivers/common/meta_blit.c
> index bbf0c3c..d150e8a 100644
> --- a/src/mesa/drivers/common/meta_blit.c
> +++ b/src/mesa/drivers/common/meta_blit.c
> @@ -707,7 +707,8 @@ _mesa_meta_BlitFramebuffer(struct gl_context *ctx,
>     /* Only scissor affects blit, but we're doing to set a custom scissor if
>      * necessary anyway, so save/clear state.
>      */
> -   _mesa_meta_begin(ctx, MESA_META_ALL & ~MESA_META_DRAW_BUFFERS);
> +   _mesa_meta_begin(ctx, MESA_META_ALL & ~(MESA_META_DRAW_BUFFERS |
> +                                           MESA_META_DITHER));
>  
>     /* If the clipping earlier changed the destination rect at all, then
>      * enable the scissor to clip to it.
> 
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