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@xxxxxxxxxx>
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
drivers/gpu/drm/drm_crtc.c | 13 +++++++------
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;
--
1.9.2
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