Add a mutex to protect resume_force_mode from being called multiple
times. This fixes a bug observed on SNB where two wake sources call
resume_force_mode and the FDI training fails as a result. The user
facing result of this is complete screen corruption.
Signed-off-by: Sean Paul <seanpaul at chromium.org>
---
drivers/gpu/drm/drm_crtc_helper.c | 8 ++++++++
drivers/gpu/drm/drm_stub.c | 1 +
include/drm/drmP.h | 1 +
3 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/drm_crtc_helper.c
b/drivers/gpu/drm/drm_crtc_helper.c
index 8111889..de7e492 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -882,6 +882,13 @@ int drm_helper_resume_force_mode(struct drm_device *dev)
struct drm_crtc_helper_funcs *crtc_funcs;
int ret;
+ /* Make sure we're not already resuming, this can really screw
+ * things up! */
+ if (mutex_trylock(&dev->resume_mutex) == 0) {
+ DRM_DEBUG("Already in resume_force_mode\n");
+ return 0;
+ }
+
list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
if (!crtc->enabled)
@@ -914,6 +921,7 @@ int drm_helper_resume_force_mode(struct drm_device *dev)
}
/* disable the unused connectors while restoring the modesetting */
drm_helper_disable_unused_functions(dev);
+ mutex_unlock(&dev->resume_mutex);
return 0;
}
EXPORT_SYMBOL(drm_helper_resume_force_mode);
diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index aa454f8..f35bed5 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -273,6 +273,7 @@ int drm_fill_in_dev(struct drm_device *dev,
spin_lock_init(&dev->count_lock);
spin_lock_init(&dev->event_lock);
mutex_init(&dev->struct_mutex);
+ mutex_init(&dev->resume_mutex);
mutex_init(&dev->ctxlist_mutex);
if (drm_ht_create(&dev->map_hash, 12)) {
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 574bd1c..75395a8 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1034,6 +1034,7 @@ struct drm_device {
/*@{ */
spinlock_t count_lock; /**< For inuse, drm_device::open_count,
drm_device::buf_use */
struct mutex struct_mutex; /**< For others */
+ struct mutex resume_mutex; /**< For drm_helper_resume_force_mode */
/*@} */
/** \name Usage Counters */
--
1.7.7.3
