[Mesa-dev] [PATCH] i965: Don't try to resolve CCS with MESA_FORMAT_NONE.

[Tapani Pälli]

FWIW this change fixes also regression on Android wallpaper since that 
commit.

On 06/04/2017 10:26 PM, Kenneth Graunke wrote:
> Since commit e9f5004d5ea38a21019e0affcd63d353b98d499a, KDE's Plasma
> Shell started crashing when intel_disable_rb_aux_buffer tried to
> dereference irb->mt, and there was no miptree.  This happened during
> intel_texture_view_requires_resolve, coming from a glClear().
> 
> Apparently intel_tex->_Format is MESA_FORMAT_NONE.  We used to translate
> MESA_FORMAT_NONE to 0, which happens to be ISL_FORMAT_R32G32B32A32_FLOAT,
> which happens to support CCS_E, so we assumed no resolves were needed.
> 
> That patch began translating MESA_FORMAT_NONE as ISL_FORMAT_UNSUPPORTED,
> which claims not to support CCS_E, so we thought we needed resolves,
> even though the buffer was in a bad state.
> 
> For now, detect intel_tex->_Format == MESA_FORMAT_NONE and bail, like
> we used to.  This is an ugly band-aid fix, but that's okay, given that
> Jason has patches on the mailing list to rewrite the resolve code.
> 
> This makes KDE usable again.
> ---
>   src/mesa/drivers/dri/i965/brw_context.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
> index 9878cae9d4b..d8219cb57e0 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.c
> +++ b/src/mesa/drivers/dri/i965/brw_context.c
> @@ -205,6 +205,9 @@ intel_texture_view_requires_resolve(struct brw_context *brw,
>          !intel_miptree_is_lossless_compressed(brw, intel_tex->mt))
>        return false;
>   
> +   if (intel_tex->_Format == MESA_FORMAT_NONE)
> +      return false;
> +
>      const enum isl_format isl_format =
>         brw_isl_format_for_mesa_format(intel_tex->_Format);
>   
>