From 0fe27f063fcef920a0be93ad5e89d9c8ef5c5858 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 23 Apr 2014 17:34:06 +0200 Subject: [PATCH] drm: Simplify fb refcounting rules around ->update_plane MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 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 --- Reading git-format-patch failed