[PATCH v2] amdgpu: check tiling flags when creating FB on GFX8-

[Alex Deucher]

On Mon, Sep 27, 2021 at 11:09 AM Simon Ser <contact at emersion.fr> wrote:
>
> On GFX9+, format modifiers are always enabled and ensure the
> frame-buffers can be scanned out at ADDFB2 time.
>
> On GFX8-, format modifiers are not supported and no other check
> is performed. This means ADDFB2 IOCTLs will succeed even if the
> tiling isn't supported for scan-out, and will result in garbage
> displayed on screen [1].
>
> Fix this by adding a check for tiling flags for GFX8 and older.
> The check is taken from radeonsi in Mesa (see how is_displayable
> is populated in gfx6_compute_surface).
>
> Changes in v2: use drm_WARN_ONCE instead of drm_WARN (Michel)
>
> [1]: https://github.com/swaywm/wlroots/issues/3185
>
> Signed-off-by: Simon Ser <contact at emersion.fr>
> Cc: stable at vger.kernel.org
> Acked-by: Michel Dänzer <mdaenzer at redhat.com>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Cc: Harry Wentland <hwentlan at amd.com>
> Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas at amd.com>
> Cc: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

Applied.  Thanks.

Alex

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 31 +++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> index 58bfc7f00d76..5faf3ef28080 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> @@ -837,6 +837,28 @@ static int convert_tiling_flags_to_modifier(struct amdgpu_framebuffer *afb)
>         return 0;
>  }
>
> +/* Mirrors the is_displayable check in radeonsi's gfx6_compute_surface */
> +static int check_tiling_flags_gfx6(struct amdgpu_framebuffer *afb)
> +{
> +       u64 micro_tile_mode;
> +
> +       /* Zero swizzle mode means linear */
> +       if (AMDGPU_TILING_GET(afb->tiling_flags, SWIZZLE_MODE) == 0)
> +               return 0;
> +
> +       micro_tile_mode = AMDGPU_TILING_GET(afb->tiling_flags, MICRO_TILE_MODE);
> +       switch (micro_tile_mode) {
> +       case 0: /* DISPLAY */
> +       case 3: /* RENDER */
> +               return 0;
> +       default:
> +               drm_dbg_kms(afb->base.dev,
> +                           "Micro tile mode %llu not supported for scanout\n",
> +                           micro_tile_mode);
> +               return -EINVAL;
> +       }
> +}
> +
>  static void get_block_dimensions(unsigned int block_log2, unsigned int cpp,
>                                  unsigned int *width, unsigned int *height)
>  {
> @@ -1103,6 +1125,7 @@ int amdgpu_display_framebuffer_init(struct drm_device *dev,
>                                     const struct drm_mode_fb_cmd2 *mode_cmd,
>                                     struct drm_gem_object *obj)
>  {
> +       struct amdgpu_device *adev = drm_to_adev(dev);
>         int ret, i;
>
>         /*
> @@ -1122,6 +1145,14 @@ int amdgpu_display_framebuffer_init(struct drm_device *dev,
>         if (ret)
>                 return ret;
>
> +       if (!dev->mode_config.allow_fb_modifiers) {
> +               drm_WARN_ONCE(dev, adev->family >= AMDGPU_FAMILY_AI,
> +                             "GFX9+ requires FB check based on format modifier\n");
> +               ret = check_tiling_flags_gfx6(rfb);
> +               if (ret)
> +                       return ret;
> +       }
> +
>         if (dev->mode_config.allow_fb_modifiers &&
>             !(rfb->base.flags & DRM_MODE_FB_MODIFIERS)) {
>                 ret = convert_tiling_flags_to_modifier(rfb);
> --
> 2.33.0
>
>