[Mesa-dev] [PATCH] r600: fix FMASK allocation on r600/700

[Marek Olšák]

bpe is in bytes, not bits, so you're overallocating the size 8 times.
No wonder it works.

As far as I can see, FMASK allocation is the same on R600 and
Evergreen. Since the allocator accepts bpe in bytes, I multiplied
nr_samples with bpp and divided by 8.

2xMSAA:
bpp = 2 bits
nr_samples = log2(bpp) = 1
final bpe = (2*1)/8 rounded up = 1

4xMSAA:
bpp = 4 bits
nr_samples = log2(bpp) = 2
final bpe = (4*2)/8 = 1

8xMSAA:
bpp = 8 bits
nr_samples = log2(bpp) = 3
final bpe = (8*3)/8 rounded up to next pow2 = 4

So you can see the code was correct. It's the tiling or alignment that
must have changed.

Marek


On Wed, Dec 10, 2014 at 3:11 AM, Dave Airlie <airlied at gmail.com> wrote:
> From: Dave Airlie <airlied at redhat.com>
>
> According to NDA docs:
> FMASK surfaces are addressed identically a surface with num_samples bits per element, and
> log2(num_samples) samples. For example, an FMASK for an 8-sample surface would be addressed
> identically to a color surface with 8 bits per element and 3 samples.
>
> Separate the r600 fmask allocation out, and workaround
> a bug in the libdrm surface allocation which blocks a 3
> sample surface, just round it up to 4.
>
> This fixes hangs with ext_framebuffer_multisample-clip-and-scissor-blit 8 msaa
> and destination clipping on my rv635.
>
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
>  src/gallium/drivers/radeon/r600_texture.c | 49 +++++++++++++++++++------------
>  1 file changed, 30 insertions(+), 19 deletions(-)
>
> diff --git a/src/gallium/drivers/radeon/r600_texture.c b/src/gallium/drivers/radeon/r600_texture.c
> index fdf4d76..3ca460a 100644
> --- a/src/gallium/drivers/radeon/r600_texture.c
> +++ b/src/gallium/drivers/radeon/r600_texture.c
> @@ -299,27 +299,38 @@ void r600_texture_get_fmask_info(struct r600_common_screen *rscreen,
>                 fmask.flags |= RADEON_SURF_HAS_TILE_MODE_INDEX;
>         }
>
> -       switch (nr_samples) {
> -       case 2:
> -       case 4:
> -               fmask.bpe = 1;
> -               if (rscreen->chip_class <= CAYMAN) {
> -                       fmask.bankh = 4;
> +       if (rscreen->chip_class <= R700) {
> +               /*
> +                * R600/700 -
> +                * FMASK surfaces are addressed identically a surface with num_samples
> +                * bits per element, and log2(num_samples) samples.
> +                */
> +               if (nr_samples != 2 && nr_samples != 4 && nr_samples != 8) {
> +                       R600_ERR("Invalid sample count for FMASK allocation.\n");
> +                       return;
>                 }
> -               break;
> -       case 8:
> -               fmask.bpe = 4;
> -               break;
> -       default:
> -               R600_ERR("Invalid sample count for FMASK allocation.\n");
> -               return;
> -       }
> +               fmask.bpe = nr_samples;
> +               fmask.nsamples = log2(nr_samples);
> +               /* surface allocator won't do 3 samples */
> +               if (fmask.nsamples == 3)
> +                       fmask.nsamples = 4;
>
> -       /* Overallocate FMASK on R600-R700 to fix colorbuffer corruption.
> -        * This can be fixed by writing a separate FMASK allocator specifically
> -        * for R600-R700 asics. */
> -       if (rscreen->chip_class <= R700) {
> -               fmask.bpe *= 2;
> +       } else {
> +               switch (nr_samples) {
> +               case 2:
> +               case 4:
> +                       fmask.bpe = 1;
> +                       if (rscreen->chip_class <= CAYMAN) {
> +                               fmask.bankh = 4;
> +                       }
> +                       break;
> +               case 8:
> +                       fmask.bpe = 4;
> +                       break;
> +               default:
> +                       R600_ERR("Invalid sample count for FMASK allocation.\n");
> +                       return;
> +               }
>         }
>
>         if (rscreen->ws->surface_init(rscreen->ws, &fmask)) {
> --
> 2.1.0
>
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