Make the docs read a little better.

Cc: Laurent Pinchart laurent.pinchart@ideasonboard.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Noralf Trønnes noralf@tronnes.org ---

Changes since version 2: - Capitalized start of sentences/descriptions - Made sure all functions have Returns: - Added some info about how things tie together

drivers/gpu/drm/drm_gem_framebuffer_helper.c | 82 ++++++++++++++++++---------- 1 file changed, 52 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c index fc7e995..aa8cb9b 100644 --- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c +++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c @@ -27,19 +27,24 @@ * DOC: overview * * This library provides helpers for drivers that don't subclass - * &drm_framebuffer and and use &drm_gem_object for their backing storage. + * &drm_framebuffer and use &drm_gem_object for their backing storage. * * Drivers without additional needs to validate framebuffers can simply use - * drm_gem_fb_create() and everything is wired up automatically. But all - * parts can be used individually. + * drm_gem_fb_create() and everything is wired up automatically. Other drivers + * can use all parts independently. */

/** - * drm_gem_fb_get_obj() - Get GEM object for framebuffer - * @fb: The framebuffer - * @plane: Which plane + * drm_gem_fb_get_obj() - Get GEM object backing the framebuffer + * @fb: Framebuffer + * @plane: Plane index * - * Returns the GEM object for given framebuffer. + * No additional reference is taken beyond the one that the &drm_frambuffer + * already holds. + * + * Returns: + * Pointer to &drm_gem_object for the given framebuffer and plane index or NULL + * if it does not exist. */ struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb, unsigned int plane) @@ -82,7 +87,7 @@ drm_gem_fb_alloc(struct drm_device *dev,

/** * drm_gem_fb_destroy - Free GEM backed framebuffer - * @fb: DRM framebuffer + * @fb: Framebuffer * * Frees a GEM backed framebuffer with its backing buffer(s) and the structure * itself. Drivers can use this as their &drm_framebuffer_funcs->destroy @@ -102,12 +107,13 @@ EXPORT_SYMBOL(drm_gem_fb_destroy);

/** * drm_gem_fb_create_handle - Create handle for GEM backed framebuffer - * @fb: DRM framebuffer - * @file: drm file - * @handle: handle created + * @fb: Framebuffer + * @file: DRM file to register the handle for + * @handle: Pointer to return the created handle * + * This function creates a handle for the GEM object backing the framebuffer. * Drivers can use this as their &drm_framebuffer_funcs->create_handle - * callback. + * callback. The GETFB IOCTL calls into this callback. * * Returns: * 0 on success or a negative error code on failure. @@ -120,18 +126,21 @@ int drm_gem_fb_create_handle(struct drm_framebuffer *fb, struct drm_file *file, EXPORT_SYMBOL(drm_gem_fb_create_handle);

/** - * drm_gem_fb_create_with_funcs() - helper function for the + * drm_gem_fb_create_with_funcs() - Helper function for the * &drm_mode_config_funcs.fb_create * callback * @dev: DRM device - * @file: drm file for the ioctl call - * @mode_cmd: metadata from the userspace fb creation request + * @file: DRM file that holds the GEM handle(s) backing the framebuffer + * @mode_cmd: Metadata from the userspace framebuffer creation request * @funcs: vtable to be used for the new framebuffer object * * This can be used to set &drm_framebuffer_funcs for drivers that need the * &drm_framebuffer_funcs.dirty callback. Use drm_gem_fb_create() if you don't * need to change &drm_framebuffer_funcs. * The function does buffer size validation. + * + * Returns: + * Pointer to a &drm_framebuffer on success or an error pointer on failure. */ struct drm_framebuffer * drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file, @@ -192,15 +201,26 @@ static const struct drm_framebuffer_funcs drm_gem_fb_funcs = { };

/** - * drm_gem_fb_create() - &drm_mode_config_funcs.fb_create callback function + * drm_gem_fb_create() - Helper function for the + * &drm_mode_config_funcs.fb_create callback * @dev: DRM device - * @file: drm file for the ioctl call - * @mode_cmd: metadata from the userspace fb creation request + * @file: DRM file that holds the GEM handle(s) backing the framebuffer + * @mode_cmd: Metadata from the userspace framebuffer creation request + * + * This function creates a new framebuffer object described by + * &drm_mode_fb_cmd2. This description includes handles for the buffer(s) + * backing the framebuffer. * * If your hardware has special alignment or pitch requirements these should be * checked before calling this function. The function does buffer size * validation. Use drm_gem_fb_create_with_funcs() if you need to set * &drm_framebuffer_funcs.dirty. + * + * Drivers can use this as their &drm_mode_config_funcs.fb_create callback. + * The ADDFB2 IOCTL calls into this callback. + * + * Returns: + * Pointer to a &drm_framebuffer on success or an error pointer on failure. */ struct drm_framebuffer * drm_gem_fb_create(struct drm_device *dev, struct drm_file *file, @@ -212,15 +232,15 @@ drm_gem_fb_create(struct drm_device *dev, struct drm_file *file, EXPORT_SYMBOL_GPL(drm_gem_fb_create);

/** - * drm_gem_fb_prepare_fb() - Prepare gem framebuffer - * @plane: Which plane - * @state: Plane state attach fence to + * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer + * @plane: Plane + * @state: Plane state the fence will be attached to * - * This can be used as the &drm_plane_helper_funcs.prepare_fb hook. - * - * This function checks if the plane FB has an dma-buf attached, extracts - * the exclusive fence and attaches it to plane state for the atomic helper - * to wait on. + * This function prepares a GEM backed framebuffer for scanout by checking if + * the plane framebuffer has a DMA-BUF attached. If it does, it extracts the + * exclusive fence and attaches it to the plane state for the atomic helper to + * wait on. This function can be used as the &drm_plane_helper_funcs.prepare_fb + * callback. * * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple * gem based framebuffer drivers which have their buffers always pinned in @@ -246,17 +266,19 @@ int drm_gem_fb_prepare_fb(struct drm_plane *plane, EXPORT_SYMBOL_GPL(drm_gem_fb_prepare_fb);

/** - * drm_gem_fbdev_fb_create - Create a drm_framebuffer for fbdev emulation + * drm_gem_fbdev_fb_create - Create a GEM backed &drm_framebuffer for fbdev + * emulation * @dev: DRM device * @sizes: fbdev size description - * @pitch_align: optional pitch alignment + * @pitch_align: Optional pitch alignment * @obj: GEM object backing the framebuffer * @funcs: vtable to be used for the new framebuffer object * - * This function creates a framebuffer for use with fbdev emulation. + * This function creates a framebuffer from a &drm_fb_helper_surface_size + * description for use in the &drm_fb_helper_funcs.fb_probe callback. * * Returns: - * Pointer to a drm_framebuffer on success or an error pointer on failure. + * Pointer to a &drm_framebuffer on success or an error pointer on failure. */ struct drm_framebuffer * drm_gem_fbdev_fb_create(struct drm_device *dev,