[PATCHv6 2/6] drm/core: Add drm_afbc_framebuffer and a corresponding helper
Emil Velikov
emil.l.velikov at gmail.com
Tue Mar 3 16:45:51 UTC 2020
Hi Andrzej,
On Tue, 3 Mar 2020 at 12:01, Andrzej Pietrasiewicz
<andrzej.p at collabora.com> wrote:
>
> The new struct contains afbc-specific data.
>
> The new function can be used by drivers which support afbc to complete
> the preparation of struct drm_afbc_framebuffer. It must be called after
> allocating the said struct and calling drm_gem_fb_init_with_funcs().
>
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p at collabora.com>
> ---
> drivers/gpu/drm/drm_gem_framebuffer_helper.c | 121 +++++++++++++++++++
> include/drm/drm_framebuffer.h | 45 +++++++
> include/drm/drm_gem_framebuffer_helper.h | 11 ++
> 3 files changed, 177 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> index 388a080cd2df..2a30f5b6829f 100644
> --- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> +++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> @@ -21,6 +21,13 @@
> #include <drm/drm_modeset_helper.h>
> #include <drm/drm_simple_kms_helper.h>
>
> +#define AFBC_HEADER_SIZE 16
> +#define AFBC_TH_LAYOUT_ALIGNMENT 8
> +#define AFBC_HDR_ALIGN 64
> +#define AFBC_SUPERBLOCK_PIXELS 256
> +#define AFBC_SUPERBLOCK_ALIGNMENT 128
> +#define AFBC_TH_BODY_START_ALIGNMENT 4096
> +
> /**
> * DOC: overview
> *
> @@ -302,6 +309,120 @@ drm_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
> }
> EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_dirty);
>
> +/**
> + * drm_afbc_get_superblock_wh - extract afbc block width/height from modifier
> + * @modifier: the modifier to be looked at
> + * @w: address of a place to store the block width
> + * @h: address of a place to store the block height
> + *
> + * Returns: true if the modifier describes a supported block size
> + */
> +bool drm_afbc_get_superblock_wh(u64 modifier, u32 *w, u32 *h)
> +{
> + switch (modifier & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) {
> + case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
> + *w = 16;
> + *h = 16;
> + break;
> + case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
> + *w = 32;
> + *h = 8;
> + break;
> + /* no user exists yet - fall through */
> + case AFBC_FORMAT_MOD_BLOCK_SIZE_64x4:
> + case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8_64x4:
> + default:
> + DRM_DEBUG_KMS("Invalid AFBC_FORMAT_MOD_BLOCK_SIZE: %lld.\n",
> + modifier & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK);
> + return false;
> + }
> + return true;
> +}
> +EXPORT_SYMBOL_GPL(drm_afbc_get_superblock_wh);
> +
> +static int drm_gem_afbc_min_size(struct drm_device *dev,
> + const struct drm_mode_fb_cmd2 *mode_cmd,
> + struct drm_afbc_framebuffer *afbc_fb)
> +{
> + const struct drm_format_info *info;
> + u32 n_blocks, w_alignment, h_alignment, hdr_alignment;
> + u32 tmp_bpp; /* remove when all users properly encode cpp in drm_format_info */
> +
> + if (!drm_afbc_get_superblock_wh(mode_cmd->modifier[0], &afbc_fb->block_width, &afbc_fb->block_height))
> + return -EINVAL;
> +
> + /* tiled header afbc */
> + w_alignment = afbc_fb->block_width;
> + h_alignment = afbc_fb->block_height;
> + hdr_alignment = AFBC_HDR_ALIGN;
> + if (mode_cmd->modifier[0] & AFBC_FORMAT_MOD_TILED) {
> + w_alignment *= AFBC_TH_LAYOUT_ALIGNMENT;
> + h_alignment *= AFBC_TH_LAYOUT_ALIGNMENT;
> + hdr_alignment = AFBC_TH_BODY_START_ALIGNMENT;
> + }
> +
> + afbc_fb->aligned_width = ALIGN(mode_cmd->width, w_alignment);
> + afbc_fb->aligned_height = ALIGN(mode_cmd->height, h_alignment);
> + afbc_fb->offset = mode_cmd->offsets[0];
> +
> + /* Change to always using info->cpp[0] when all users properly encode it */
> + info = drm_get_format_info(dev, mode_cmd);
> + tmp_bpp = info->cpp[0] ? info->cpp[0] * 8 : afbc_fb->bpp;
> +
> + n_blocks = (afbc_fb->aligned_width * afbc_fb->aligned_height) / AFBC_SUPERBLOCK_PIXELS;
> + afbc_fb->afbc_size = ALIGN(n_blocks * AFBC_HEADER_SIZE, hdr_alignment);
> + afbc_fb->afbc_size += n_blocks * ALIGN(tmp_bpp * AFBC_SUPERBLOCK_PIXELS / 8, AFBC_SUPERBLOCK_ALIGNMENT);
> +
> + return 0;
> +}
> +
> +/**
> + * drm_gem_fb_afbc_init() - Helper function for drivers using afbc to
> + * fill and validate all the afbc-specific
> + * struct drm_afbc_framebuffer members
> + *
> + * @dev: DRM device
> + * @afbc_fb: afbc-specific framebuffer
> + * @mode_cmd: Metadata from the userspace framebuffer creation request
> + * @afbc_fb: afbc framebuffer
> + *
> + * This function can be used by drivers which support afbc to complete
> + * the preparation of struct drm_afbc_framebuffer. It must be called after
> + * allocating the said struct and calling drm_gem_fb_init_with_funcs().
> + *
> + * Returns:
> + * Zero on success or a negative error value on failure.
> + */
> +int drm_gem_fb_afbc_init(struct drm_device *dev, const struct drm_mode_fb_cmd2 *mode_cmd,
> + struct drm_afbc_framebuffer *afbc_fb)
> +{
> + const struct drm_format_info *info;
> + struct drm_gem_object **objs;
> + int ret = -EINVAL, i;
> +
> + objs = afbc_fb->base.obj;
> + info = drm_get_format_info(dev, mode_cmd);
> + if (!info)
> + goto error;
> +
> + ret = drm_gem_afbc_min_size(dev, mode_cmd, afbc_fb);
> + if (ret < 0)
> + goto error;
> +
> + if (objs[0]->size < afbc_fb->afbc_size) {
> + ret = -EINVAL;
> + goto error;
> + }
> +
> + return 0;
> +
> +error:
> + for (i = 0; i < info->num_planes; i++)
> + drm_gem_object_put_unlocked(objs[i]);
> +
Here we put and object we did not get. This type of asymmetric API
usage isn't common, thus it's fairly fragile.
Let's leave the put in the caller.
> + return ret;
> +}
> +
> /**
> * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer
> * @plane: Plane
> diff --git a/include/drm/drm_framebuffer.h b/include/drm/drm_framebuffer.h
> index c0e0256e3e98..e9f1b0e2968d 100644
> --- a/include/drm/drm_framebuffer.h
> +++ b/include/drm/drm_framebuffer.h
> @@ -297,4 +297,49 @@ int drm_framebuffer_plane_width(int width,
> int drm_framebuffer_plane_height(int height,
> const struct drm_framebuffer *fb, int plane);
>
> +/**
> + * struct drm_afbc_framebuffer - a special afbc frame buffer object
> + *
> + * A derived class of struct drm_framebuffer, dedicated for afbc use cases.
> + */
> +struct drm_afbc_framebuffer {
> + /**
> + * @base: base framebuffer structure.
> + */
> + struct drm_framebuffer base;
> + /**
> + * @block_widht: width of a single afbc block
> + */
> + u32 block_width;
> + /**
> + * @block_widht: height of a single afbc block
> + */
> + u32 block_height;
> + /**
> + * @aligned_width: aligned frame buffer width
> + */
> + u32 aligned_width;
> + /**
> + * @aligned_height: aligned frame buffer height
> + */
> + u32 aligned_height;
> + /**
> + * @offset: offset of the first afbc header
> + */
> + u32 offset;
> + /**
> + * @afbc_size: minimum size of afbc buffer
> + */
> + u32 afbc_size;
> + /**
> + * @bpp: bpp value for this afbc buffer
> + * To be removed when users such as malidp
> + * properly store the cpp in drm_format_info.
> + * New users should not start using this field.
> + */
Are you planning to look into this? Alternatively let's add an entry
in Documentation/gpu/todo.rst.
Nit: Line wrap the newly introduced code to 80 columns.
IIRC scripts/checkpatch.pl will complain loudly about it.
-Emil
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