drm/core: Add drm_afbc_framebuffer and a corresponding helper

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 <[e-mail]>
Reviewed-by: Emil Velikov <[e-mail]>
Reviewed-by: James Qian Wang <[e-mail]>
Acked-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/gpu/todo.rst

···
 
 Level: Intermediate
 
+Encode cpp properly in malidp
+-----------------------------
+
+cpp (chars per pixel) is not encoded properly in malidp, zero is
+used instead. afbc implementation needs bpp or cpp, but if it is
+zero it needs to be provided elsewhere, and so the bpp field exists
+in struct drm_afbc_framebuffer.
+
+Properly encode cpp in malidp and remove the bpp field in struct
+drm_afbc_framebuffer.
+
+Contact: malidp maintainers
+
+Level: Intermediate
+
 Core refactorings
 =================
 

drivers/gpu/drm/drm_gem_framebuffer_helper.c

···
 #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
  *
···
 					    &drm_gem_fb_funcs_dirtyfb);
 }
 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_dirty);
+
+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;
+	/* remove bpp when all users properly encode cpp in drm_format_info */
+	__u32 bpp;
+
+	switch (mode_cmd->modifier[0] & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) {
+	case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
+		afbc_fb->block_width = 16;
+		afbc_fb->block_height = 16;
+		break;
+	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
+		afbc_fb->block_width = 32;
+		afbc_fb->block_height = 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",
+			      mode_cmd->modifier[0]
+			      & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK);
+		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];
+
+	info = drm_get_format_info(dev, mode_cmd);
+	/*
+	 * Change to always using info->cpp[0]
+	 * when all users properly encode it
+	 */
+	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(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().
+ * It is caller's responsibility to put afbc_fb->base.obj objects in case
+ * the call is unsuccessful.
+ *
+ * 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;
+
+	objs = afbc_fb->base.obj;
+	info = drm_get_format_info(dev, mode_cmd);
+	if (!info)
+		return -EINVAL;
+
+	ret = drm_gem_afbc_min_size(dev, mode_cmd, afbc_fb);
+	if (ret < 0)
+		return ret;
+
+	if (objs[0]->size < afbc_fb->afbc_size)
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(drm_gem_fb_afbc_init);
 
 /**
  * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer

include/drm/drm_framebuffer.h

···
 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.
+	 */
+	u32 bpp;
+};
+
+#define fb_to_afbc_fb(x) container_of(x, struct drm_afbc_framebuffer, base)
+
 #endif

include/drm/drm_gem_framebuffer_helper.h

···
 #ifndef __DRM_GEM_FB_HELPER_H__
 #define __DRM_GEM_FB_HELPER_H__
 
+struct drm_afbc_framebuffer;
 struct drm_device;
 struct drm_fb_helper_surface_size;
 struct drm_file;
···
 struct drm_plane;
 struct drm_plane_state;
 struct drm_simple_display_pipe;
+
+#define AFBC_VENDOR_AND_TYPE_MASK	GENMASK_ULL(63, 52)
 
 struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
 					  unsigned int plane);
···
 struct drm_framebuffer *
 drm_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
 			     const struct drm_mode_fb_cmd2 *mode_cmd);
+
+#define drm_is_afbc(modifier) \
+	(((modifier) & AFBC_VENDOR_AND_TYPE_MASK) == DRM_FORMAT_MOD_ARM_AFBC(0))
+
+int drm_gem_fb_afbc_init(struct drm_device *dev,
+			 const struct drm_mode_fb_cmd2 *mode_cmd,
+			 struct drm_afbc_framebuffer *afbc_fb);
 
 int drm_gem_fb_prepare_fb(struct drm_plane *plane,
 			  struct drm_plane_state *state);