[ 074/221] drm/radeon: avoid deadlock in pm path when waiting for fence

Greg Kroah-Hartman
2013-01-16T00:30:07Z

From: Jerome Glisse <jglisse@redhat.com>

commit 5f8f635edd8ad5a6416bff4c5ff486500357f473 upstream.

radeon_fence_wait_empty_locked should not trigger GPU reset as no
place where it's call from would benefit from such thing and it
actually lead to a kernel deadlock in case the reset is triggered
from pm codepath. Instead force ring completion in place where it
makes sense or return early in others.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/radeon/radeon.h | 2 +-
drivers/gpu/drm/radeon/radeon_device.c | 13 +++++++++++--
drivers/gpu/drm/radeon/radeon_fence.c | 30 ++++++++++++++----------------
drivers/gpu/drm/radeon/radeon_pm.c | 15 ++++++++++++---
4 files changed, 38 insertions(+), 22 deletions(-)

--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -226,7 +226,7 @@ void radeon_fence_process(struct radeon_
bool radeon_fence_signaled(struct radeon_fence *fence);
int radeon_fence_wait(struct radeon_fence *fence, bool interruptible);
int radeon_fence_wait_next_locked(struct radeon_device *rdev, int ring);
-void radeon_fence_wait_empty_locked(struct radeon_device *rdev, int ring);
+int radeon_fence_wait_empty_locked(struct radeon_device *rdev, int ring);
int radeon_fence_wait_any(struct radeon_device *rdev,
struct radeon_fence **fences,
bool intr);
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1163,6 +1163,7 @@ int radeon_suspend_kms(struct drm_device
struct drm_crtc *crtc;
struct drm_connector *connector;
int i, r;
+ bool force_completion = false;

if (dev == NULL || dev->dev_private == NULL) {
return -ENODEV;
@@ -1205,8 +1206,16 @@ int radeon_suspend_kms(struct drm_device

mutex_lock(&rdev->ring_lock);
/* wait for gpu to finish processing current batch */
- for (i = 0; i < RADEON_NUM_RINGS; i++)
- radeon_fence_wait_empty_locked(rdev, i);
+ for (i = 0; i < RADEON_NUM_RINGS; i++) {
+ r = radeon_fence_wait_empty_locked(rdev, i);
+ if (r) {
+ /* delay GPU reset to resume */
+ force_completion = true;
+ }
+ }
+ if (force_completion) {
+ radeon_fence_driver_force_completion(rdev);
+ }
mutex_unlock(&rdev->ring_lock);

radeon_save_bios_scratch_regs(rdev);
--- a/drivers/gpu/drm/radeon/radeon_fence.c
+++ b/drivers/gpu/drm/radeon/radeon_fence.c
@@ -609,26 +609,20 @@ int radeon_fence_wait_next_locked(struct
* Returns 0 if the fences have passed, error for all other cases.
* Caller must hold ring lock.
*/
-void radeon_fence_wait_empty_locked(struct radeon_device *rdev, int ring)
+int radeon_fence_wait_empty_locked(struct radeon_device *rdev, int ring)
{
uint64_t seq = rdev->fence_drv[ring].sync_seq[ring];
+ int r;

- while(1) {
- int r;
- r = radeon_fence_wait_seq(rdev, seq, ring, false, false);
+ r = radeon_fence_wait_seq(rdev, seq, ring, false, false);
+ if (r) {
if (r == -EDEADLK) {
- mutex_unlock(&rdev->ring_lock);
- r = radeon_gpu_reset(rdev);
- mutex_lock(&rdev->ring_lock);
- if (!r)
- continue;
- }
- if (r) {
- dev_err(rdev->dev, "error waiting for ring to become"
- " idle (%d)\n", r);
+ return -EDEADLK;
}
- return;
+ dev_err(rdev->dev, "error waiting for ring[%d] to become idle (%d)\n",
+ ring, r);
}
+ return 0;
}

/**
@@ -854,13 +848,17 @@ int radeon_fence_driver_init(struct rade
*/
void radeon_fence_driver_fini(struct radeon_device *rdev)
{
- int ring;
+ int ring, r;

mutex_lock(&rdev->ring_lock);
for (ring = 0; ring < RADEON_NUM_RINGS; ring++) {
if (!rdev->fence_drv[ring].initialized)
continue;
- radeon_fence_wait_empty_locked(rdev, ring);
+ r = radeon_fence_wait_empty_locked(rdev, ring);
+ if (r) {
+ /* no need to trigger GPU reset as we are unloading */
+ radeon_fence_driver_force_completion(rdev);
+ }
wake_up_all(&rdev->fence_queue);
radeon_scratch_free(rdev, rdev->fence_drv[ring].scratch_reg);
rdev->fence_drv[ring].initialized = false;
--- a/drivers/gpu/drm/radeon/radeon_pm.c
+++ b/drivers/gpu/drm/radeon/radeon_pm.c
@@ -234,7 +234,7 @@ static void radeon_set_power_state(struc

static void radeon_pm_set_clocks(struct radeon_device *rdev)
{
- int i;
+ int i, r;

/* no need to take locks, etc. if nothing's going to change */
if ((rdev->pm.requested_clock_mode_index == rdev->pm.current_clock_mode_index) &&
@@ -248,8 +248,17 @@ static void radeon_pm_set_clocks(struct
/* wait for the rings to drain */
for (i = 0; i < RADEON_NUM_RINGS; i++) {
struct radeon_ring *ring = &rdev->ring[i];
- if (ring->ready)
- radeon_fence_wait_empty_locked(rdev, i);
+ if (!ring->ready) {
+ continue;
+ }
+ r = radeon_fence_wait_empty_locked(rdev, i);
+ if (r) {
+ /* needs a GPU reset dont reset here */
+ mutex_unlock(&rdev->ring_lock);
+ up_write(&rdev->pm.mclk_lock);
+ mutex_unlock(&rdev->ddev->struct_mutex);
+ return;
+ }
}

radeon_unmap_vram_bos(rdev);