[Mesa-dev] [PATCH] st/mesa: fix glReadBuffer() assertion failure

[Roland Scheidegger]

Am 08.04.2016 um 01:45 schrieb Brian Paul:
> If the first call in a GL app is glReadPixels(GL_FRONT) we'd fail the
> assert(st->ctx->FragmentProgram._Current) at st_atom_shader.c:114 in
> update_fp().
> 
> This is because we were calling st_validate_state() without first
> updating Mesa state with _mesa_update_state().
> 
> The regression came from commit 83b589301f4a150f4 "st/mesa: fix
> frontbuffer glReadPixels regressions".
> 
> The new piglit gl-1.0-simple-readbuffer test exercises this.
> 
> Cc: "11.1 11.2" <mesa-stable at lists.freedesktop.org>
> ---
>  src/mesa/state_tracker/st_cb_fbo.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/src/mesa/state_tracker/st_cb_fbo.c b/src/mesa/state_tracker/st_cb_fbo.c
> index ff570e0..456ad83 100644
> --- a/src/mesa/state_tracker/st_cb_fbo.c
> +++ b/src/mesa/state_tracker/st_cb_fbo.c
> @@ -40,6 +40,7 @@
>  #include "main/glformats.h"
>  #include "main/macros.h"
>  #include "main/renderbuffer.h"
> +#include "main/state.h"
>  
>  #include "pipe/p_context.h"
>  #include "pipe/p_defines.h"
> @@ -729,6 +730,7 @@ st_ReadBuffer(struct gl_context *ctx, GLenum buffer)
>         fb->Attachment[fb->_ColorReadBufferIndex].Type == GL_NONE) {
>        /* add the buffer */
>        st_manager_add_color_renderbuffer(st, fb, fb->_ColorReadBufferIndex);
> +      _mesa_update_state(ctx);
>        st_validate_state(st, ST_PIPELINE_RENDER);
>     }
>  }
> 

Looks ok to me, though it looks bugs come and go in that area. But not
sure if the mechanism could be made more robust...

Reviewed-by: Roland Scheidegger <sroland at vmware.com>