Re: [PATCH v2] drm: support hotspot for universal plane cursors

[John Keeping <john@metanate.com>]

On Tue, 17 Nov 2015 17:39:32 +0200, Ville Syrjälä wrote:

> On Tue, Nov 17, 2015 at 03:05:34PM +0000, John Keeping wrote:
> > The request's hot_x and hot_y are set correctly for both
> > DRM_IOCTL_MODE_CURSOR and DRM_IOCTL_MODE_CURSOR2 so we just need to
> > save the values and then apply the offset to the cursor plane when
> > the cursor moves.
> > 
> > Signed-off-by: John Keeping <john@metanate.com>
> > ---
> > v2:
> >   - add kerneldoc for hot_x and hot_y in struct drm_crtc
> > 
> >  drivers/gpu/drm/drm_crtc.c | 11 +++++++----
> >  include/drm/drm_crtc.h     |  6 ++++++
> >  2 files changed, 13 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> > index 720a153..40f5b84 100644
> > --- a/drivers/gpu/drm/drm_crtc.c
> > +++ b/drivers/gpu/drm/drm_crtc.c
> > @@ -2831,6 +2831,9 @@ static int drm_mode_cursor_universal(struct
> > drm_crtc *crtc, DRM_DEBUG_KMS("failed to wrap cursor buffer in drm
> > framebuffer\n"); return PTR_ERR(fb);
> >  			}
> > +
> > +			crtc->hot_x = req->hot_x;
> > +			crtc->hot_y = req->hot_y;
> >  		} else {
> >  			fb = NULL;
> >  		}
> > @@ -2841,11 +2844,11 @@ static int drm_mode_cursor_universal(struct
> > drm_crtc *crtc, }
> >  
> >  	if (req->flags & DRM_MODE_CURSOR_MOVE) {
> > -		crtc_x = req->x;
> > -		crtc_y = req->y;
> > +		crtc_x = req->x - crtc->hot_x;
> > +		crtc_y = req->y - crtc->hot_y;
> >  	} else {
> > -		crtc_x = crtc->cursor_x;
> > -		crtc_y = crtc->cursor_y;
> > +		crtc_x = crtc->cursor_x - crtc->hot_x;
> > +		crtc_y = crtc->cursor_y - crtc->hot_y;  
> 
> Why does the location of the hotspot affect the plane position?

hot_{x,y} specify the location of the active pixel within the cursor
plane and cursor_{x,y} specify the location of the active pixel on the
display so we need to offset the plane position in order for the active
pixel to be in the correct place.

> >  	}
> >  
> >  	if (fb) {
> > diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> > index 3f0c690..2be4414 100644
> > --- a/include/drm/drm_crtc.h
> > +++ b/include/drm/drm_crtc.h
> > @@ -404,6 +404,8 @@ struct drm_crtc_funcs {
> >   * @cursor: cursor plane for this CRTC
> >   * @cursor_x: current x position of the cursor, used for universal
> > cursor planes
> >   * @cursor_y: current y position of the cursor, used for universal
> > cursor planes
> > + * @hot_x: x-coordinate of cursor hotspot, used for universal
> > cursor planes
> > + * @hot_y: y-coordinate of cursor hotspot, used for universal
> > cursor planes
> >   * @enabled: is this CRTC enabled?
> >   * @mode: current mode timings
> >   * @hwmode: mode timings as programmed to hw regs
> > @@ -445,6 +447,10 @@ struct drm_crtc {
> >  	int cursor_x;
> >  	int cursor_y;
> >  
> > +	/* hotspot of cursor */
> > +	int hot_x;
> > +	int hot_y;
> > +
> >  	bool enabled;
> >  
> >  	/* Requested mode from modesetting. */
> > -- 
> > 2.6.3.462.gbe2c914
> > 
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>