[Mesa-dev] [PATCH 1/2] i965: Correct a mistake that always forced texture tiling.

[Matt Turner]

On Tue, Aug 4, 2015 at 11:18 PM, Matt Turner <mattst88 at gmail.com> wrote:
> Regression since commit 3a31876600, when tiling modes were moved into
> layout_flags.
>
> The relevant enum values are
>
>    MIPTREE_LAYOUT_ALLOC_YTILED = 1 << 5
>    MIPTREE_LAYOUT_ALLOC_XTILED = 1 << 6
>    MIPTREE_LAYOUT_ALLOC_ANY_TILED = MIPTREE_LAYOUT_ALLOC_YTILED |
>                                     MIPTREE_LAYOUT_ALLOC_XTILED
>    MIPTREE_LAYOUT_ALLOC_LINEAR = 1 << 7
>
> so the expression (layout_flags & MIPTREE_LAYOUT_ALLOC_ANY_TILED) can
> never produce a value of MIPTREE_LAYOUT_ALLOC_LINEAR.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91513
> ---
> I find this code really weird. MIPTREE_LAYOUT_ALLOC_XTILED is only used
> in the two places noted in the commit message, and it wasn't an enum
> value in the intel_miptree_tiling_mode type removed in the aforementioned
> commit. Even with this patch, the brw_miptree_choose_tiling() function
> wouldn't do anything sensible if passed XTILED | ~YTILED in layout_flags.
> In fact, that case isn't even handled by the switch statement...
>
>  src/mesa/drivers/dri/i965/brw_tex_layout.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> w
> diff --git a/src/m esa/drivers/dri/i965/brw_tex_layout.c b/src/mesa/drivers/dri/i965/brw_tex_layout.c
> index fb78b08..8f492e3 100644
> --- a/src/mesa/drivers/dri/i965/brw_tex_layout.c
> +++ b/src/mesa/drivers/dri/i965/brw_tex_layout.c
> @@ -633,11 +633,11 @@ brw_miptree_choose_tiling(struct brw_context *brw,
>     switch (layout_flags & MIPTREE_LAYOUT_ALLOC_ANY_TILED) {
>     case MIPTREE_LAYOUT_ALLOC_ANY_TILED:
>        break;
>     case MIPTREE_LAYOUT_ALLOC_YTILED:
>        return I915_TILING_Y;
> -   case MIPTREE_LAYOUT_ALLOC_LINEAR:
> +   case 0:

Maybe a better fix is to include LINEAR in the definition of ANY? I
suspect that matches the previous behavior better than this.

>        return I915_TILING_NONE;
>     }
>
>     if (mt->num_samples > 1) {
>        /* From p82 of the Sandy Bridge PRM, dw3[1] of SURFACE_STATE ("Tiled
> --
> 2.3.6