From: Daniel Vetter Date: Tue, 4 Nov 2014 21:57:27 +0000 (+0100) Subject: drm/atomic: Refcounting for plane_state->fb X-Git-Tag: omap-for-v3.20/drop-legacy-3517~77^2~75^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=321ebf04dc7ab5c54d658f93db0ffe35277664ab;p=pandora-kernel.git drm/atomic: Refcounting for plane_state->fb So my original plan was that the drm core refcounts framebuffers like with the legacy ioctls. But that doesn't work for a bunch of reasons: - State objects might live longer than until the next fb change happens for a plane. For example delayed cleanup work only happens _after_ the pageflip ioctl has completed. So this definitely doesn't work without the plane state holding its own references. - The other issue is transition from legacy to atomic implementations, where the driver works under a mix of both worlds. Which means legacy paths might not properly update the ->fb pointer under plane->state->fb. Which is a bit a problem when then someone comes around and _does_ try to clean it up when it's long gone. The second issue is just a bit a transition bug, since drivers should update plane->state->fb in all the paths that aren't converted yet. But a bit more robustness for the transition can't hurt - we pull similar tricks with cleaning up the old fb in the transitional helpers already. The pattern for drivers that transition is if (plane->state) drm_atomic_set_fb_for_plane(plane->state, plane->fb); inserted after the fb update has logically completed at the end of ->set_config (or ->set_base/mode_set if using the crtc helpers), ->page_flip, ->update_plane or any other entry point which updates plane->fb. v2: Update kerneldoc - copypasta fail. v3: Fix spelling in the commit message (Sean). Reviewed-by: Sean Paul Signed-off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index ad15a88c0f74..ed991ba66e21 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -367,6 +367,34 @@ drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state, } EXPORT_SYMBOL(drm_atomic_set_crtc_for_plane); +/** + * drm_atomic_set_fb_for_plane - set crtc for plane + * @plane_state: atomic state object for the plane + * @fb: fb to use for the plane + * + * Changing the assigned framebuffer for a plane requires us to grab a reference + * to the new fb and drop the reference to the old fb, if there is one. This + * function takes care of all these details besides updating the pointer in the + * state object itself. + */ +void +drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state, + struct drm_framebuffer *fb) +{ + if (plane_state->fb) + drm_framebuffer_unreference(plane_state->fb); + if (fb) + drm_framebuffer_reference(fb); + plane_state->fb = fb; + + if (fb) + DRM_DEBUG_KMS("Set [FB:%d] for plane state %p\n", + fb->base.id, plane_state); + else + DRM_DEBUG_KMS("Set [NOFB] for plane state %p\n", plane_state); +} +EXPORT_SYMBOL(drm_atomic_set_fb_for_plane); + /** * drm_atomic_set_crtc_for_connector - set crtc for connector * @conn_state: atomic state object for the connector diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 2b1db0c12fdc..ca839bd9bb0d 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1182,7 +1182,7 @@ retry: ret = drm_atomic_set_crtc_for_plane(plane_state, crtc); if (ret != 0) goto fail; - plane_state->fb = fb; + drm_atomic_set_fb_for_plane(plane_state, fb); plane_state->crtc_x = crtc_x; plane_state->crtc_y = crtc_y; plane_state->crtc_h = crtc_h; @@ -1250,7 +1250,7 @@ retry: ret = drm_atomic_set_crtc_for_plane(plane_state, NULL); if (ret != 0) goto fail; - plane_state->fb = NULL; + drm_atomic_set_fb_for_plane(plane_state, NULL); plane_state->crtc_x = 0; plane_state->crtc_y = 0; plane_state->crtc_h = 0; @@ -1422,7 +1422,7 @@ retry: ret = drm_atomic_set_crtc_for_plane(primary_state, crtc); if (ret != 0) goto fail; - primary_state->fb = set->fb; + drm_atomic_set_fb_for_plane(primary_state, set->fb); primary_state->crtc_x = 0; primary_state->crtc_y = 0; primary_state->crtc_h = set->mode->vdisplay; @@ -1694,7 +1694,7 @@ retry: ret = drm_atomic_set_crtc_for_plane(plane_state, crtc); if (ret != 0) goto fail; - plane_state->fb = fb; + drm_atomic_set_fb_for_plane(plane_state, fb); ret = drm_atomic_async_commit(state); if (ret != 0) @@ -1808,6 +1808,9 @@ EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state); */ void drm_atomic_helper_plane_reset(struct drm_plane *plane) { + if (plane->state && plane->state->fb) + drm_framebuffer_unreference(plane->state->fb); + kfree(plane->state); plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL); } @@ -1823,10 +1826,17 @@ EXPORT_SYMBOL(drm_atomic_helper_plane_reset); struct drm_plane_state * drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane) { + struct drm_plane_state *state; + if (WARN_ON(!plane->state)) return NULL; - return kmemdup(plane->state, sizeof(*plane->state), GFP_KERNEL); + state = kmemdup(plane->state, sizeof(*plane->state), GFP_KERNEL); + + if (state && state->fb) + drm_framebuffer_reference(state->fb); + + return state; } EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state); @@ -1839,8 +1849,11 @@ EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state); * subclassed plane state structure. */ void drm_atomic_helper_plane_destroy_state(struct drm_plane *plane, - struct drm_plane_state *state) + struct drm_plane_state *state) { + if (state->fb) + drm_framebuffer_unreference(state->fb); + kfree(state); } EXPORT_SYMBOL(drm_atomic_helper_plane_destroy_state); Reading git-diff-tree failed