[PATCH 05/10] drm/doc: Polish for drm_plane.[hc]

[Daniel Vetter]

On Fri, Sep 02, 2016 at 03:00:38PM +0530, Archit Taneja wrote:
> 
> 
> On 8/31/2016 9:39 PM, Daniel Vetter wrote:
> > Big thing is untangling and carefully documenting the different uapi
> > types of planes. I also sprinkled a few more cross references around
> > to make this easier to discover.
> > 
> > As usual, remove the kerneldoc for internal functions which are not
> > exported. Aside: We should probably go OCD on all the ioctl handlers
> > and consistenly give them an _ioctl postfix.
> > 
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> >   Documentation/gpu/drm-kms.rst |  47 +--------------
> >   drivers/gpu/drm/drm_crtc.c    |   6 +-
> >   drivers/gpu/drm/drm_plane.c   | 132 ++++++++----------------------------------
> >   include/drm/drm_plane.h       |  57 +++++++++++++++++-
> >   4 files changed, 86 insertions(+), 156 deletions(-)
> > 
> <snip>
> 
> > +/**
> > + * enum drm_plane_type - uapi plane type enumeration
> > + *
> > + * For historical reasons not all planes are made the same. This enumeration is
> > + * used to tell the different types of planes apart to implement the different
> > + * uapi semantics for them. For userspace which is universal plane aware and
> > + * which is using that atomic IOCTL there's no difference between these planes
> > + * (beyong what the driver and hardware can support of course).
> > + *
> > + * For compatibility with legacy userspace, only overlay planes are made
> > + * available to userspace by default. Userspace clients may set the
> > + * DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that they
> > + * wish to receive a universal plane list containing all plane types. See also
> > + * drm_for_each_legacy_plane().
> > + */
> >   enum drm_plane_type {
> > -	DRM_PLANE_TYPE_OVERLAY,
> 
> Any reason why you moved this down? I guess there is no harm, but people
> might be printing plane type while debugging, and they'd assume
> DRM_PLANE_TYPE_OVERLAY=0

I think starting out with 0 for the primary plane makes a lot more sense,
and since it's an internal thing we can change it however we want. I also
think from a documentation pov it reads better if the 2 special planes
(primary and cursor) are first.

But I'm happy to shuffle it back if you feel strongly the other way round.
-Daniel

> 
> Thanks,
> Archit
> 
> > +	/**
> > +	 * @DRM_PLANE_TYPE_PRIMARY:
> > +	 *
> > +	 * Primary planes represent a "main" plane for a CRTC.  Primary planes
> > +	 * are the planes operated upon by CRTC modesetting and flipping
> > +	 * operations described in the page_flip and set_config hooks in struct
> > +	 * &drm_crtc_funcs.
> > +	 */
> >   	DRM_PLANE_TYPE_PRIMARY,
> > +
> > +	/**
> > +	 * @DRM_PLANE_TYPE_CURSOR:
> > +	 *
> > +	 * Cursor planes represent a "cursor" plane for a CRTC.  Cursor planes
> > +	 * are the planes operated upon by the DRM_IOCTL_MODE_CURSOR and
> > +	 * DRM_IOCTL_MODE_CURSOR2 IOCTLs.
> > +	 */
> >   	DRM_PLANE_TYPE_CURSOR,
> > +
> > +	/**
> > +	 * @DRM_PLANE_TYPE_OVERLAY:
> > +	 *
> > +	 * Overlay planes represent all non-primary, non-cursor planes. Some
> > +	 * drivers refer to these types of planes as "sprites" internally.
> > +	 */
> > +	DRM_PLANE_TYPE_OVERLAY,
> >   };
> > 
> > 
> > @@ -458,11 +496,26 @@ static inline struct drm_plane *drm_plane_find(struct drm_device *dev,
> >   	list_for_each_entry((plane), &(dev)->mode_config.plane_list, head) \
> >   		for_each_if ((plane_mask) & (1 << drm_plane_index(plane)))
> > 
> > -/* Plane list iterator for legacy (overlay only) planes. */
> > +/**
> > + * drm_for_each_legacy_plane - iterate over all planes for legacy userspace
> > + * @plane: the loop cursor
> > + * @dev: the DRM device
> > + *
> > + * Iterate over all legacy planes of @dev, excluding primary and cursor planes.
> > + * This is useful for implementing userspace apis when userspace is not
> > + * universal plane aware. See also enum &drm_plane_type.
> > + */
> >   #define drm_for_each_legacy_plane(plane, dev) \
> >   	list_for_each_entry(plane, &(dev)->mode_config.plane_list, head) \
> >   		for_each_if (plane->type == DRM_PLANE_TYPE_OVERLAY)
> > 
> > +/**
> > + * drm_for_each_plane - iterate over all planes
> > + * @plane: the loop cursor
> > + * @dev: the DRM device
> > + *
> > + * Iterate over all planes of @dev, include primary and cursor planes.
> > + */
> >   #define drm_for_each_plane(plane, dev) \
> >   	list_for_each_entry(plane, &(dev)->mode_config.plane_list, head)
> > 
> > 
> 
> -- 
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch