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authorDaniel Vetter <daniel.vetter@ffwll.ch>2014-04-23 17:34:06 +0200
committerDaniel Vetter <daniel.vetter@ffwll.ch>2014-04-23 20:06:47 +0200
commit0fe27f063fcef920a0be93ad5e89d9c8ef5c5858 (patch)
treea9cbdea36556a405dca0e01d3aba21f8e41ae422 /drivers/gpu/drm/drm_plane_helper.c
parent49d9ec1ca62a4341f387617258107a5ee7f7b3ed (diff)
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drm: Simplify fb refcounting rules around ->update_plane
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 <treding@nvidia.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Matt Roper <matthew.d.roper@intel.com> Reviewed-by: Matt Roper <matthew.d.roper@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'drivers/gpu/drm/drm_plane_helper.c')
-rw-r--r--drivers/gpu/drm/drm_plane_helper.c10
1 files changed, 1 insertions, 9 deletions
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;