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

[Michel Dänzer]

On 2021-09-20 12:31, Simon Ser 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).
> 
> [1]: https://github.com/swaywm/wlroots/issues/3185
> 
> Signed-off-by: Simon Ser <contact at emersion.fr>
> Cc: stable at vger.kernel.org
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Cc: Harry Wentland <hwentlan at amd.com>
> Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas at amd.com>
> Cc: Michel Dänzer <michel at daenzer.net>
> Cc: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
> ---
>  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..dfe434a56a8c 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(dev, adev->family >= AMDGPU_FAMILY_AI,
> +			 "GFX9+ requires FB check based on format modifier\n");

drm_WARN_ONCE would be better, to avoid spamming dmesg if there's a driver bug.


With that,

Acked-by: Michel Dänzer <mdaenzer at redhat.com>


-- 
Earthling Michel Dänzer            |                  https://redhat.com
Libre software enthusiast          |         Mesa and Xwayland developer