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author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2014-04-23 17:34:06 +0200 |
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committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2014-04-23 20:06:47 +0200 |
commit | 0fe27f063fcef920a0be93ad5e89d9c8ef5c5858 (patch) | |
tree | a9cbdea36556a405dca0e01d3aba21f8e41ae422 | |
parent | 49d9ec1ca62a4341f387617258107a5ee7f7b3ed (diff) | |
download | linux-0fe27f063fcef920a0be93ad5e89d9c8ef5c5858.tar.gz linux-0fe27f063fcef920a0be93ad5e89d9c8ef5c5858.tar.bz2 linux-0fe27f063fcef920a0be93ad5e89d9c8ef5c5858.zip |
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>
-rw-r--r-- | drivers/gpu/drm/drm_crtc.c | 13 | ||||
-rw-r--r-- | drivers/gpu/drm/drm_plane_helper.c | 10 |
2 files changed, 8 insertions, 15 deletions
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index d8b7099abece..f6633cb927bc 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -1145,16 +1145,17 @@ EXPORT_SYMBOL(drm_plane_cleanup); */ void drm_plane_force_disable(struct drm_plane *plane) { + struct drm_framebuffer *old_fb = plane->fb; int ret; - if (!plane->fb) + if (!old_fb) return; ret = plane->funcs->disable_plane(plane); if (ret) DRM_ERROR("failed to disable plane with busy fb\n"); /* disconnect the plane from the fb and crtc: */ - __drm_framebuffer_unreference(plane->fb); + __drm_framebuffer_unreference(old_fb); plane->fb = NULL; plane->crtc = NULL; } @@ -2187,16 +2188,18 @@ int drm_mode_setplane(struct drm_device *dev, void *data, } drm_modeset_lock_all(dev); + old_fb = plane->fb; ret = plane->funcs->update_plane(plane, crtc, fb, plane_req->crtc_x, plane_req->crtc_y, plane_req->crtc_w, plane_req->crtc_h, plane_req->src_x, plane_req->src_y, plane_req->src_w, plane_req->src_h); if (!ret) { - old_fb = plane->fb; plane->crtc = crtc; plane->fb = fb; fb = NULL; + } else { + old_fb = NULL; } drm_modeset_unlock_all(dev); @@ -2239,9 +2242,7 @@ int drm_mode_set_config_internal(struct drm_mode_set *set) ret = crtc->funcs->set_config(set); if (ret == 0) { crtc->primary->crtc = crtc; - - /* crtc->fb must be updated by ->set_config, enforces this. */ - WARN_ON(fb != crtc->primary->fb); + crtc->primary->fb = fb; } list_for_each_entry(tmp, &crtc->dev->mode_config.crtc_list, head) { 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; |