From 0fe27f063fcef920a0be93ad5e89d9c8ef5c5858 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 23 Apr 2014 17:34:06 +0200 Subject: drm: Simplify fb refcounting rules around ->update_plane MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The introduction of primary planes has apparently caused a bit of fb refcounting fun for people. That makes it a good time to clean up the arcane rules and slight differences between ->update_plane and ->set_config. The new rules are: - The core holds a reference for both the new and the old fb (if they're non-NULL of course) while calling into the driver through either ->update_plane or ->set_config. - Drivers may not clobber plane->fb if their callback fails. If they do that, they need to store a pointer to the old fb in it again. When calling into the driver plane->fb still points at the current (old) framebuffer. - The core will update the plane->fb pointer on success. Drivers can do that themselves too, but aren't required to any more for the primary plane. - The core will update fb refcounts for the plane->fb pointer, presuming the drivers hold up their end of the bargain. v2: Remove now unused tmpfb (Thierry) v3: Drop broken changes from drm_mode_setplane (Ville). Also polish the commit message a bit. v4: Also fix up the handling of ->disable_plane in drm_plane_force_disable. The issue was that we didn't save plane->fb over the ->disable_plane call. Just paranoia, nothing relies on this. v5: Keep still useful comments about directly calling ->set_config, which I should have done for v4 already. Requested by Matt. Cc: Thierry Reding Cc: Ville Syrjälä Cc: Matt Roper Reviewed-by: Matt Roper Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_plane_helper.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) (limited to 'drivers/gpu/drm/drm_plane_helper.c') diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c index 9540ff9f97fe..d966afa7ecae 100644 --- a/drivers/gpu/drm/drm_plane_helper.c +++ b/drivers/gpu/drm/drm_plane_helper.c @@ -124,7 +124,6 @@ int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc, .y2 = crtc->mode.vdisplay, }; struct drm_connector **connector_list; - struct drm_framebuffer *tmpfb; int num_connectors, ret; if (!crtc->enabled) { @@ -178,21 +177,14 @@ int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc, set.num_connectors = num_connectors; /* - * set_config() adjusts crtc->primary->fb; however the DRM setplane - * code that called us expects to handle the framebuffer update and - * reference counting; save and restore the current fb before - * calling it. - * - * N.B., we call set_config() directly here rather than using + * We call set_config() directly here rather than using * drm_mode_set_config_internal. We're reprogramming the same * connectors that were already in use, so we shouldn't need the extra * cross-CRTC fb refcounting to accomodate stealing connectors. * drm_mode_setplane() already handles the basic refcounting for the * framebuffers involved in this operation. */ - tmpfb = plane->fb; ret = crtc->funcs->set_config(&set); - plane->fb = tmpfb; kfree(connector_list); return ret; -- cgit v1.2.3