[Intel-gfx] [PATCH 01/19] drm: Wire up proper acquire ctx for plane functions

[Daniel Vetter]

On Mon, Mar 27, 2017 at 04:12:05PM -0400, Harry Wentland wrote:
> On Wednesday, March 22, 2017 10:50:40 PM EDT Daniel Vetter wrote:
> > This is just prep work to get an acquire ctx into every place where we
> > call ->update_plane or ->disable_plane.
> > 
> > v2: Keep the hidden acquire_ctx pointers valid while transitioning.
> > 
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> >  drivers/gpu/drm/drm_plane.c | 52
> > ++++++++++++++++++++++++++++++++++++--------- 1 file changed, 42
> > insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> > index a22e76837065..0d04888172a7 100644
> > --- a/drivers/gpu/drm/drm_plane.c
> > +++ b/drivers/gpu/drm/drm_plane.c
> > @@ -457,7 +457,8 @@ static int __setplane_internal(struct drm_plane *plane,
> >  			       uint32_t crtc_w, uint32_t crtc_h,
> >  			       /* src_{x,y,w,h} values are 16.16 fixed point */
> >  			       uint32_t src_x, uint32_t src_y,
> > -			       uint32_t src_w, uint32_t src_h)
> > +			       uint32_t src_w, uint32_t src_h,
> > +			       struct drm_modeset_acquire_ctx *ctx)
> >  {
> >  	int ret = 0;
> > 
> > @@ -537,13 +538,26 @@ static int setplane_internal(struct drm_plane *plane,
> >  			     uint32_t src_x, uint32_t src_y,
> >  			     uint32_t src_w, uint32_t src_h)
> >  {
> > +	struct drm_modeset_acquire_ctx ctx;
> >  	int ret;
> > 
> > -	drm_modeset_lock_all(plane->dev);
> > +	drm_modeset_acquire_init(&ctx, 0);
> > +retry:
> > +	ret = drm_modeset_lock_all_ctx(plane->dev, &ctx);
> > +	if (ret)
> > +		goto fail;
> > +	plane->dev->mode_config.acquire_ctx = &ctx;
> >  	ret = __setplane_internal(plane, crtc, fb,
> >  				  crtc_x, crtc_y, crtc_w, crtc_h,
> > -				  src_x, src_y, src_w, src_h);
> > -	drm_modeset_unlock_all(plane->dev);
> > +				  src_x, src_y, src_w, src_h, &ctx);
> > +
> > +fail:
> > +	if (ret == -EDEADLK) {
> > +		drm_modeset_backoff(&ctx);
> > +		goto retry;
> > +	}
> > +	drm_modeset_drop_locks(&ctx);
> > +	drm_modeset_acquire_fini(&ctx);
> > 
> >  	return ret;
> >  }
> > @@ -613,11 +627,22 @@ static int drm_mode_cursor_universal(struct drm_crtc
> > *crtc, int32_t crtc_x, crtc_y;
> >  	uint32_t crtc_w = 0, crtc_h = 0;
> >  	uint32_t src_w = 0, src_h = 0;
> > +	struct drm_modeset_acquire_ctx ctx;
> >  	int ret = 0;
> > 
> >  	BUG_ON(!crtc->cursor);
> >  	WARN_ON(crtc->cursor->crtc != crtc && crtc->cursor->crtc != NULL);
> > 
> > +	drm_modeset_acquire_init(&ctx, 0);
> > +retry:
> > +	ret = drm_modeset_lock(&crtc->mutex, &ctx);
> > +	if (ret)
> > +		goto fail;
> > +	ret = drm_modeset_lock(&crtc->cursor->mutex, &ctx);
> > +	if (ret)
> > +		goto fail;
> > +	crtc->acquire_ctx = &ctx;
> > +
> >  	/*
> >  	 * Obtain fb we'll be using (either new or existing) and take an extra
> >  	 * reference to it if fb != null.  setplane will take care of dropping
> > @@ -662,7 +687,7 @@ static int drm_mode_cursor_universal(struct drm_crtc
> > *crtc, */
> >  	ret = __setplane_internal(crtc->cursor, crtc, fb,
> >  				crtc_x, crtc_y, crtc_w, crtc_h,
> > -				0, 0, src_w, src_h);
> > +				0, 0, src_w, src_h, &ctx);
> > 
> >  	/* Update successful; save new cursor position, if necessary */
> >  	if (ret == 0 && req->flags & DRM_MODE_CURSOR_MOVE) {
> > @@ -670,6 +695,15 @@ static int drm_mode_cursor_universal(struct drm_crtc
> > *crtc, crtc->cursor_y = req->y;
> >  	}
> > 
> > +fail:
> > +	if (ret == -EDEADLK) {
> > +		drm_modeset_backoff(&ctx);
> > +		goto retry;
> > +	}
> > +
> > +	drm_modeset_drop_locks(&ctx);
> > +	drm_modeset_acquire_fini(&ctx);
> > +
> >  	return ret;
> >  }
> > 
> > @@ -696,12 +730,10 @@ static int drm_mode_cursor_common(struct drm_device
> > *dev, * If this crtc has a universal cursor plane, call that plane's update
> > * handler rather than using legacy cursor handlers.
> >  	 */
> > -	drm_modeset_lock_crtc(crtc, crtc->cursor);
> > -	if (crtc->cursor) {
> > -		ret = drm_mode_cursor_universal(crtc, req, file_priv);
> > -		goto out;
> > -	}
> > +	if (crtc->cursor)
> > +		return drm_mode_cursor_universal(crtc, req, file_priv);
> > 
> > +	drm_modeset_lock_crtc(crtc, crtc->cursor);
> 
> Why are you moving the lock? Shouldn't it still be covering the call to 
> drm_mode_cursor_universal?

It would deadlock, because the new acquire ctx dance for universal planes
also takes the same locks as this helper?

But I just realized that crtc->cursor is NULL here, I can simplify this
some more.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch