[Mesa-dev] [PATCH] intel/isl: Avoid tiling on 16K-wide render targets

[Andres Gomez]

That was quick! ☺

On Fri, 2018-07-27 at 16:02 -0700, Nanley Chery wrote:
> Fix rendering issues on BDW and SKL.
> 
> Fixes 0288fe8d0417730bdd5b3477130dd1dc32bdbcd3
> ("i965/miptree: Use the correct BLT pitch")

I'd add here some lines listing the tests fixed by this patch.

> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107359
> Cc: <mesa-stable at lists.freedesktop.org>

This is:

Tested-by: Andres Gomez <agomez at igalia.com>

> ---
> 
> We could probably add an assert when filling out the surface state, but
> I think BLORP would need a non-trivial amount of work done as a
> prerequisite. I'm thinking specifically of the cases where we bind a
> depth buffer as a render target.
> 
> I won't be able to push anything until about a week from EOD today, so
> if this does end up getting reviewed, please feel free to push it.
> 
>  src/intel/isl/isl_gen7.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/src/intel/isl/isl_gen7.c b/src/intel/isl/isl_gen7.c
> index 4fa9851233f..2d85f4b568d 100644
> --- a/src/intel/isl/isl_gen7.c
> +++ b/src/intel/isl/isl_gen7.c
> @@ -294,6 +294,25 @@ isl_gen6_filter_tiling(const struct isl_device *dev,
>      */
>     if (ISL_DEV_GEN(dev) < 7 && isl_format_get_layout(info->format)->bpb >= 128)
>        *flags &= ~ISL_TILING_Y0_BIT;
> +
> +   /* From the BDW and SKL PRMs, Volume 2d,
> +    * RENDER_SURFACE_STATE::Width - Programming Notes:
> +    *
> +    *   A known issue exists if a primitive is rendered to the first 2 rows and
> +    *   last 2 columns of a 16K width surface. If any geometry is drawn inside
> +    *   this square it will be copied to column X=2 and X=3 (arrangement on Y
> +    *   position will stay the same). If any geometry exceeds the boundaries of
> +    *   this 2x2 region it will be drawn normally. The issue also only occurs
> +    *   if the surface has TileMode != Linear.
> +    *
> +    * To prevent this rendering corruption, only allow linear tiling for
> +    * surfaces with widths greater than 16K-2 pixels.
> +    */
> +   if (info->width > 16382 &&
> +       info->usage & ISL_SURF_USAGE_RENDER_TARGET_BIT &&
> +       (ISL_DEV_GEN(dev) == 8 || dev->info->is_skylake)) {
> +          *flags &= ISL_TILING_LINEAR_BIT;
> +   }
>  }
>  
>  void
-- 
Br,

Andres