drm: Create a format/modifier blob

Updated blob layout (Rob, Daniel, Kristian, xerpi)

v2:
* Removed __packed, and alignment (.+)
* Fix indent in drm_format_modifier fields (Liviu)
* Remove duplicated modifier > 64 check (Liviu)
* Change comment about modifier (Liviu)
* Remove arguments to blob creation, use plane instead (Liviu)
* Fix data types (Ben)
* Make the blob part of uapi (Daniel)

v3:
Remove unused ret field.
Change i, and j to unsigned int (Emil)

v4:
Use plane->modifier_count instead of recounting (Daniel)

v5:
Rename modifiers to modifiers_property (Ville)
Use sizeof(__u32) instead to reflect UAPI nature (Ville)
Make BUILD_BUG_ON for blob header size

Cc: Rob Clark <robdclark@gmail.com>
Cc: Kristian H. Kristensen <hoegsberg@gmail.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Daniel Stone <daniels@collabora.com> (v2)
Reviewed-by: Liviu Dudau <liviu@dudau.co.uk> (v2)
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com> (v3)
Signed-off-by: Daniel Stone <daniels@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170724034641.13369-2-ben@bwidawsk.net

drivers/gpu/drm/drm_mode_config.c

@@ -337,6 +337,13 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
 		return -ENOMEM;
 	dev->mode_config.gamma_lut_size_property = prop;
 
+	prop = drm_property_create(dev,
+				   DRM_MODE_PROP_IMMUTABLE | DRM_MODE_PROP_BLOB,
+				   "IN_FORMATS", 0);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.modifiers_property = prop;
+
 	return 0;
 }
 

drivers/gpu/drm/drm_plane.c

@@ -62,6 +62,87 @@ static unsigned int drm_num_planes(struct drm_device *dev)
 	return num;
 }
 
+static inline u32 *
+formats_ptr(struct drm_format_modifier_blob *blob)
+{
+	return (u32 *)(((char *)blob) + blob->formats_offset);
+}
+
+static inline struct drm_format_modifier *
+modifiers_ptr(struct drm_format_modifier_blob *blob)
+{
+	return (struct drm_format_modifier *)(((char *)blob) + blob->modifiers_offset);
+}
+
+static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane)
+{
+	const struct drm_mode_config *config = &dev->mode_config;
+	struct drm_property_blob *blob;
+	struct drm_format_modifier *mod;
+	size_t blob_size, formats_size, modifiers_size;
+	struct drm_format_modifier_blob *blob_data;
+	unsigned int i, j;
+
+	formats_size = sizeof(__u32) * plane->format_count;
+	if (WARN_ON(!formats_size)) {
+		/* 0 formats are never expected */
+		return 0;
+	}
+
+	modifiers_size =
+		sizeof(struct drm_format_modifier) * plane->modifier_count;
+
+	blob_size = sizeof(struct drm_format_modifier_blob);
+	/* Modifiers offset is a pointer to a struct with a 64 bit field so it
+	 * should be naturally aligned to 8B.
+	 */
+	BUILD_BUG_ON(sizeof(struct drm_format_modifier_blob) % 8);
+	blob_size += ALIGN(formats_size, 8);
+	blob_size += modifiers_size;
+
+	blob = drm_property_create_blob(dev, blob_size, NULL);
+	if (IS_ERR(blob))
+		return -1;
+
+	blob_data = (struct drm_format_modifier_blob *)blob->data;
+	blob_data->version = FORMAT_BLOB_CURRENT;
+	blob_data->count_formats = plane->format_count;
+	blob_data->formats_offset = sizeof(struct drm_format_modifier_blob);
+	blob_data->count_modifiers = plane->modifier_count;
+
+	blob_data->modifiers_offset =
+		ALIGN(blob_data->formats_offset + formats_size, 8);
+
+	memcpy(formats_ptr(blob_data), plane->format_types, formats_size);
+
+	/* If we can't determine support, just bail */
+	if (!plane->funcs->format_mod_supported)
+		goto done;
+
+	mod = modifiers_ptr(blob_data);
+	for (i = 0; i < plane->modifier_count; i++) {
+		for (j = 0; j < plane->format_count; j++) {
+			if (plane->funcs->format_mod_supported(plane,
+							       plane->format_types[j],
+							       plane->modifiers[i])) {
+
+				mod->formats |= 1 << j;
+			}
+		}
+
+		mod->modifier = plane->modifiers[i];
+		mod->offset = 0;
+		mod->pad = 0;
+		mod++;
+	}
+
+done:
+	drm_object_attach_property(&plane->base, config->modifiers_property,
+				   blob->base.id);
+
+	return 0;
+}
+
 /**
  * drm_universal_plane_init - Initialize a new universal plane object
  * @dev: DRM device
@@ -181,6 +262,9 @@ int drm_universal_plane_init(struct drm_device *dev, struct drm_plane *plane,
 		drm_object_attach_property(&plane->base, config->prop_src_h, 0);
 	}
 
+	if (config->allow_fb_modifiers)
+		create_in_format_blob(dev, plane);
+
 	return 0;
 }
 EXPORT_SYMBOL(drm_universal_plane_init);

include/drm/drm_mode_config.h

@@ -757,6 +757,12 @@ struct drm_mode_config {
 	 */
 	bool allow_fb_modifiers;
 
+	/**
+	 * @modifiers: Plane property to list support modifier/format
+	 * combination.
+	 */
+	struct drm_property *modifiers_property;
+
 	/* cursor size */
 	uint32_t cursor_width, cursor_height;
 

include/uapi/drm/drm_mode.h

@@ -712,6 +712,56 @@ struct drm_mode_atomic {
 	__u64 user_data;
 };
 
+struct drm_format_modifier_blob {
+#define FORMAT_BLOB_CURRENT 1
+	/* Version of this blob format */
+	u32 version;
+
+	/* Flags */
+	u32 flags;
+
+	/* Number of fourcc formats supported */
+	u32 count_formats;
+
+	/* Where in this blob the formats exist (in bytes) */
+	u32 formats_offset;
+
+	/* Number of drm_format_modifiers */
+	u32 count_modifiers;
+
+	/* Where in this blob the modifiers exist (in bytes) */
+	u32 modifiers_offset;
+
+	/* u32 formats[] */
+	/* struct drm_format_modifier modifiers[] */
+};
+
+struct drm_format_modifier {
+	/* Bitmask of formats in get_plane format list this info applies to. The
+	 * offset allows a sliding window of which 64 formats (bits).
+	 *
+	 * Some examples:
+	 * In today's world with < 65 formats, and formats 0, and 2 are
+	 * supported
+	 * 0x0000000000000005
+	 *		  ^-offset = 0, formats = 5
+	 *
+	 * If the number formats grew to 128, and formats 98-102 are
+	 * supported with the modifier:
+	 *
+	 * 0x0000003c00000000 0000000000000000
+	 *		  ^
+	 *		  |__offset = 64, formats = 0x3c00000000
+	 *
+	 */
+	__u64 formats;
+	__u32 offset;
+	__u32 pad;
+
+	/* The modifier that applies to the >get_plane format list bitmask. */
+	__u64 modifier;
+};
+
 /**
  * Create a new 'blob' data property, copying length bytes from data pointer,
  * and returning new blob ID.