Re: [PATCH v2 4/5] drm: Add support for handling linear tile formats

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Aug 21, 2018 at 07:30:03PM +0100, Alexandru Gheorghe wrote:
> The previous patch added tile_w and tile_h, which represent the
> horizontal and vertical sizes of a tile.
> 
> This one uses that to plumb through drm core in order to be able to
> handle linear tile formats without the need for drivers to roll up
> their own implementation.
> 
> This patch had been written with Mali-dp X0L2 and X0L0 in mind which
> is a 1 plane YCbCr 420 format with a 2x2 tile, that uses in average 2
> bytes per pixel and where tiles are laid out in a linear manner.
> 
> Now what are the restrictions:
> 
> 1. Pitch in bytes is expected to cover at least tile_h * width in
> pixels. Due to this the places where the pitch is checked/used need to
> be updated to take into consideration the tile_w, tile_h and
> tile_size.
>     tile_size = cpp * tile_w * tile_h
> 
> 2. When doing source cropping plane_src_x/y need to be a multiple of
> tile_w/tile_h and we need to take into consideration the tile_w/tile_h
> when computing the start address.
> 
> For all non-tiled formats the tile_w and tile_h will be 1, so if I
> didn't miss anything nothing should change.
> 
> Regarding multi-planar linear tile formats, I'm not sure how those
> should be handle I kind of assumed that tile_h/tile_w will have to be
> divided by horizontal/subsampling. Anyway, I think it's best to just
> put an warning in there and handle it when someone tries to add
> support for them.
> 
> Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
> ---
>  drivers/gpu/drm/drm_atomic.c                 |  8 +++
>  drivers/gpu/drm/drm_fb_cma_helper.c          | 11 ++++-
>  drivers/gpu/drm/drm_fourcc.c                 | 52 ++++++++++++++++++++
>  drivers/gpu/drm/drm_framebuffer.c            | 19 +++++--
>  drivers/gpu/drm/drm_gem_framebuffer_helper.c | 10 ++--
>  include/drm/drm_fourcc.h                     |  2 +
>  6 files changed, 94 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 3eb061e11e2e..7a3e893a4cd1 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -1087,6 +1087,14 @@ static int drm_atomic_plane_check(struct drm_plane *plane,
>  		return -ENOSPC;
>  	}
>  
> +	/* Make sure source coordinates are a multiple of tile sizes */
> +	if ((state->src_x >> 16) % state->fb->format->tile_w ||
> +	    (state->src_y >> 16) % state->fb->format->tile_h) {
> +		DRM_DEBUG_ATOMIC("[PLANE:%d:%s] Source coordinates do not meet tile restrictions",
> +				 plane->base.id, plane->name);
> +		return -EINVAL;
> +	}

Feels rather wrong to me to put such hardware specific limitations into
the core.

> +
>  	if (plane_switching_crtc(state->state, plane, state)) {
>  		DRM_DEBUG_ATOMIC("[PLANE:%d:%s] switching CRTC directly\n",
>  				 plane->base.id, plane->name);
> diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
> index 47e0e2f6642d..4d8052adce67 100644
> --- a/drivers/gpu/drm/drm_fb_cma_helper.c
> +++ b/drivers/gpu/drm/drm_fb_cma_helper.c
> @@ -87,6 +87,8 @@ dma_addr_t drm_fb_cma_get_gem_addr(struct drm_framebuffer *fb,
>  	struct drm_gem_cma_object *obj;
>  	dma_addr_t paddr;
>  	u8 h_div = 1, v_div = 1;
> +	u32 tile_w = drm_format_tile_width(fb->format, plane);
> +	u32 tile_h = drm_format_tile_height(fb->format, plane);
>  
>  	obj = drm_fb_cma_get_gem_obj(fb, plane);
>  	if (!obj)
> @@ -99,8 +101,13 @@ dma_addr_t drm_fb_cma_get_gem_addr(struct drm_framebuffer *fb,
>  		v_div = fb->format->vsub;
>  	}
>  
> -	paddr += (fb->format->cpp[plane] * (state->src_x >> 16)) / h_div;
> -	paddr += (fb->pitches[plane] * (state->src_y >> 16)) / v_div;
> +	paddr += (fb->format->cpp[plane] * tile_w * (state->src_x >> 16))
> +			/ h_div;
> +	/*
> +	 * For tile formats pitches are expected to cover at least
> +	 * width * tile_h pixels
> +	 */
> +	paddr += ((fb->pitches[plane] / tile_h) * (state->src_y >> 16)) / v_div;
>  
>  	return paddr;
>  }
> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> index f55cd93ba2d0..d6c9c5aa4036 100644
> --- a/drivers/gpu/drm/drm_fourcc.c
> +++ b/drivers/gpu/drm/drm_fourcc.c
> @@ -557,3 +557,55 @@ int drm_format_plane_height(int height, uint32_t format, int plane)
>  	return height / info->vsub;
>  }
>  EXPORT_SYMBOL(drm_format_plane_height);
> +
> +/**
> + * drm_format_tile_width - width of a tile for tile formats, should be 1 for all
> + * non-tiled formats.
> + * @format: pixel format
> + * @plane: plane index
> + *
> + * Returns:
> + * The width of a tile, depending on the plane index and horizontal sub-sampling
> + */
> +uint32_t drm_format_tile_width(const struct drm_format_info *info, int plane)
> +{
> +	WARN_ON(!info->tile_w);
> +	if (plane == 0 || info->tile_w == 1)
> +		return info->tile_w;
> +
> +	/*
> +	 * Multi planar tiled formats have never been tested, check that
> +	 * buffer restrictions and source cropping meet the format layout
> +	 * expectations.
> +	 */
> +	WARN_ON("Multi-planar tiled formats unsupported");
> +	WARN_ON(info->tile_w % info->hsub);
> +	return info->tile_w / info->hsub;
> +}
> +EXPORT_SYMBOL(drm_format_tile_width);
> +
> +/**
> + * drm_format_tile_height - height of a tile for tile formats, should be 1 for
> + * all non-tiled formats.
> + * @format: pixel format
> + * @plane: plane index
> + *
> + * Returns:
> + * The height of a tile, depending on the plane index and vertical sub-sampling
> + */
> +uint32_t drm_format_tile_height(const struct drm_format_info *info, int plane)
> +{
> +	WARN_ON(!info->tile_h);
> +	if (plane == 0 || info->tile_h == 1)
> +		return info->tile_h;
> +
> +	/*
> +	 * Multi planar tiled formats have never been tested, check that
> +	 * buffer restrictions and source cropping meet the format layout
> +	 * expectations.
> +	 */
> +	WARN_ON("Multi-planar tiled formats unsupported");
> +	WARN_ON(info->tile_h % info->vsub);
> +	return info->tile_h / info->vsub;
> +}
> +EXPORT_SYMBOL(drm_format_tile_height);
> diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c
> index 781af1d42d76..57509e51cb80 100644
> --- a/drivers/gpu/drm/drm_framebuffer.c
> +++ b/drivers/gpu/drm/drm_framebuffer.c
> @@ -191,19 +191,32 @@ static int framebuffer_check(struct drm_device *dev,
>  		unsigned int width = fb_plane_width(r->width, info, i);
>  		unsigned int height = fb_plane_height(r->height, info, i);
>  		unsigned int cpp = info->cpp[i];
> +		unsigned int tile_w = drm_format_tile_width(info, i);
> +		unsigned int tile_h = drm_format_tile_height(info, i);
> +		unsigned int tile_size = cpp * tile_w * tile_h;
> +		unsigned int num_htiles;
> +		unsigned int num_vtiles;
>  
>  		if (!r->handles[i]) {
>  			DRM_DEBUG_KMS("no buffer object handle for plane %d\n", i);
>  			return -EINVAL;
>  		}
>  
> -		if ((uint64_t) width * cpp > UINT_MAX)
> +		if ((width % tile_w) || (height % tile_h)) {
> +			DRM_DEBUG_KMS("buffer width/height need to be a multiple of tile dimensions\n");
> +			return -EINVAL;
> +		}
> +
> +		num_htiles = width / tile_w;
> +		num_vtiles = height / tile_h;
> +
> +		if ((uint64_t)num_htiles * tile_size > UINT_MAX)
>  			return -ERANGE;
>  
> -		if ((uint64_t) height * r->pitches[i] + r->offsets[i] > UINT_MAX)
> +		if ((uint64_t)num_vtiles * r->pitches[i] + r->offsets[i] > UINT_MAX)
>  			return -ERANGE;
>  
> -		if (r->pitches[i] < width * cpp) {
> +		if (r->pitches[i] < num_htiles * tile_size) {
>  			DRM_DEBUG_KMS("bad pitch %u for plane %d\n", r->pitches[i], i);
>  			return -EINVAL;
>  		}
> diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> index 2810d4131411..3d01a1a9d5d2 100644
> --- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> +++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> @@ -161,6 +161,11 @@ drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file,
>  		unsigned int width = mode_cmd->width / (i ? info->hsub : 1);
>  		unsigned int height = mode_cmd->height / (i ? info->vsub : 1);
>  		unsigned int min_size;
> +		unsigned int tile_w = drm_format_tile_width(info, i);
> +		unsigned int tile_h = drm_format_tile_height(info, i);
> +		unsigned int tile_size = info->cpp[i] * tile_w * tile_h;
> +		unsigned int num_htiles = width / tile_w;
> +		unsigned int num_vtiles = height / tile_h;
>  
>  		objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]);
>  		if (!objs[i]) {
> @@ -169,9 +174,8 @@ drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file,
>  			goto err_gem_object_put;
>  		}
>  
> -		min_size = (height - 1) * mode_cmd->pitches[i]
> -			 + width * info->cpp[i]
> -			 + mode_cmd->offsets[i];
> +		min_size = (num_vtiles - 1) * mode_cmd->pitches[i]
> +			 + num_htiles * tile_size + mode_cmd->offsets[i];
>  
>  		if (objs[i]->size < min_size) {
>  			drm_gem_object_put_unlocked(objs[i]);
> diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
> index 41681cf2b140..001afca9bcff 100644
> --- a/include/drm/drm_fourcc.h
> +++ b/include/drm/drm_fourcc.h
> @@ -76,6 +76,8 @@ int drm_format_horz_chroma_subsampling(uint32_t format);
>  int drm_format_vert_chroma_subsampling(uint32_t format);
>  int drm_format_plane_width(int width, uint32_t format, int plane);
>  int drm_format_plane_height(int height, uint32_t format, int plane);
> +uint32_t drm_format_tile_width(const struct drm_format_info *info, int plane);
> +uint32_t drm_format_tile_height(const struct drm_format_info *info, int plane);
>  const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf *buf);
>  
>  #endif /* __DRM_FOURCC_H__ */
> -- 
> 2.18.0
> 
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-- 
Ville Syrjälä
Intel
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