Re: [PATCH 6/8] drm/amd/display: Set DC options from modifiers.

From: daniel@ffwll.ch
Cc: amd-gfx@lists.freedesktop.org, maraeo@gmail.com,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 6/8] drm/amd/display: Set DC options from modifiers.
Date: Wed, 5 Aug 2020 09:32:10 +0200	[thread overview]
Message-ID: <20200805073210.GU6419@phenom.ffwll.local> (raw)
In-Reply-To: <20200804213119.25091-7-bas@basnieuwenhuizen.nl>

On Tue, Aug 04, 2020 at 11:31:17PM +0200, Bas Nieuwenhuizen wrote:
> This sets the DC tiling options from the modifier, if modifiers
> are used for the FB. This patch by itself does not expose the
> support yet though.
> 
> There is not much validation yet to limit the scope of this
> patch, but the current validation is at the same level as
> the BO metadata path.
> 
> Signed-off-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
> ---
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 109 +++++++++++++++++-
>  1 file changed, 103 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 6ef7f2f8acab..ac913b8f10ef 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3754,6 +3754,93 @@ fill_gfx9_plane_attributes_from_flags(struct amdgpu_device *adev,
>  	return 0;
>  }
>  
> +static bool
> +modifier_has_dcc(uint64_t modifier)
> +{
> +	return IS_AMD_FMT_MOD(modifier) && AMD_FMT_MOD_GET(DCC, modifier);
> +}
> +
> +static unsigned
> +modifier_gfx9_swizzle_mode(uint64_t modifier)
> +{
> +	if (modifier == DRM_FORMAT_MOD_LINEAR)
> +		return 0;
> +
> +	return AMD_FMT_MOD_GET(TILE, modifier);
> +}
> +
> +static void
> +fill_gfx9_tiling_info_from_modifier(const struct amdgpu_device *adev,
> +				  union dc_tiling_info *tiling_info,
> +				  uint64_t modifier)
> +{
> +	unsigned int mod_bank_xor_bits = AMD_FMT_MOD_GET(BANK_XOR_BITS, modifier);
> +	unsigned int mod_pipe_xor_bits = AMD_FMT_MOD_GET(PIPE_XOR_BITS, modifier);
> +	unsigned int pkrs_log2 = AMD_FMT_MOD_GET(PACKERS, modifier);
> +	unsigned int pipes_log2 = min(4u, mod_pipe_xor_bits);
> +
> +	fill_gfx9_tiling_info_from_device(adev, tiling_info);
> +
> +	if (!IS_AMD_FMT_MOD(modifier))
> +		return;
> +
> +	tiling_info->gfx9.num_pipes = 1u << pipes_log2;
> +	tiling_info->gfx9.num_shader_engines = 1u << (mod_pipe_xor_bits - pipes_log2);
> +
> +	if (adev->family >= AMDGPU_FAMILY_NV) {
> +		tiling_info->gfx9.num_pkrs = 1u << pkrs_log2;
> +	} else {
> +		tiling_info->gfx9.num_banks = 1u << mod_bank_xor_bits;
> +
> +		/* for DCC we know it isn't rb aligned, so rb_per_se doesn't matter. */
> +	}
> +}
> +
> +static void
> +block_alignment(unsigned int blocksize_log2, unsigned int *width, unsigned int *height)
> +{
> +	unsigned int height_log2 = blocksize_log2 / 2;
> +	unsigned int width_log2 = blocksize_log2 - height_log2;
> +
> +	*width = 1u << width_log2;
> +	*height = 1u << height_log2;
> +}
> +
> +static int
> +fill_gfx9_plane_attributes_from_modifiers(struct amdgpu_device *adev,
> +				      const struct amdgpu_framebuffer *afb,
> +				      const enum surface_pixel_format format,
> +				      const enum dc_rotation_angle rotation,
> +				      const struct plane_size *plane_size,
> +				      union dc_tiling_info *tiling_info,
> +				      struct dc_plane_dcc_param *dcc,
> +				      struct dc_plane_address *address,
> +				      const bool force_disable_dcc)
> +{
> +	const uint64_t modifier = afb->base.modifier;
> +	int ret;
> +
> +	fill_gfx9_tiling_info_from_modifier(adev, tiling_info, modifier);
> +	tiling_info->gfx9.swizzle = modifier_gfx9_swizzle_mode(modifier);
> +
> +	if (modifier_has_dcc(modifier) && !force_disable_dcc) {
> +		uint64_t dcc_address = afb->address + afb->base.offsets[1];
> +
> +		dcc->enable = 1;
> +		dcc->meta_pitch = afb->base.pitches[1];
> +		dcc->independent_64b_blks = AMD_FMT_MOD_GET(DCC_INDEPENDENT_64B, modifier);
> +
> +		address->grph.meta_addr.low_part = lower_32_bits(dcc_address);
> +		address->grph.meta_addr.high_part = upper_32_bits(dcc_address);
> +	}
> +
> +	ret = validate_dcc(adev, format, rotation, tiling_info, dcc, address, plane_size);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
>  static int
>  fill_plane_buffer_attributes(struct amdgpu_device *adev,
>  			     const struct amdgpu_framebuffer *afb,
> @@ -3823,12 +3910,22 @@ fill_plane_buffer_attributes(struct amdgpu_device *adev,
>  
>  
>  	if (adev->family >= AMDGPU_FAMILY_AI) {
> -		ret = fill_gfx9_plane_attributes_from_flags(adev, afb, format, rotation,
> -							    plane_size, tiling_info, dcc,
> -							    address, tiling_flags,
> -							    force_disable_dcc);
> -		if (ret)
> -			return ret;
> +		if (afb->base.flags & DRM_MODE_FB_MODIFIERS) {
> +			ret = fill_gfx9_plane_attributes_from_modifiers(adev, afb, format,
> +								      rotation, plane_size,
> +								      tiling_info, dcc,
> +								      address,
> +								      force_disable_dcc);
> +			if (ret)
> +				return ret;
> +		} else {
> +			ret = fill_gfx9_plane_attributes_from_flags(adev, afb, format, rotation,
> +								  plane_size, tiling_info, dcc,
> +								  address, tiling_flags,
> +								  force_disable_dcc);
> +			if (ret)
> +				return ret;

So what we've done in i915, but might be too cumbersome with the amdgpu
modifiers, is to map legacy tiling information into modifiers once, at the
beginning of addfb. So in amdgpu_display_user_framebuffer_create(). And
once modifiers are filled in, you ofc set the DRM_MODE_FB_MODIFIERS flag
too in the fb.

Then all the display code only works with modifiers, instead of having a
mix and possible confusion, with breakage when people only test the legacy
path. Which I kinda expect to happen, since amd probably runs with their
own ddx in their CI rig only.

This also avoids a bunch of layering and locking unprettiness, since
display code doesn't need to dig around in gem_bo side of things. On that,
there's another amdgpu_bo_get_tiling_flags in amdgpu_dm_commit_planes
which probably shouldn't be there, and should use computed stuff from
plane state or fb (I changed it to a lockless version to just hack around
locking issues, but still there).

This hopefully/eventually should allow us to entirely phase out the legacy
magic tiling blob attached to bo (we've pulled the trigger on that for
intel now, would have needed to extend the uapi to keep it working was a
good excuse).

Cheers, Daniel

> +		}
>  	} else {
>  		fill_gfx8_tiling_info_from_flags(tiling_info, tiling_flags);
>  	}
> -- 
> 2.28.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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