drm/radeon: avoid deadlock in pm path when waiting for fence

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>
Cc: stable@vger.kernel.org

4 files changed, 38 insertions, 22 deletions

diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index aae73141d63a..9b9422c4403a 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -231,7 +231,7 @@ void radeon_fence_process(struct radeon_device *rdev, int ring);
 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);
diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index e81d6cab9959..a6617b53a9c6 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1164,6 +1164,7 @@ int radeon_suspend_kms(struct drm_device *dev, pm_message_t state)
         struct drm_crtc *crtc;
         struct drm_connector *connector;
         int i, r;
+        bool force_completion = false;
 
         if (dev == NULL || dev->dev_private == NULL) {
                 return -ENODEV;
@@ -1206,8 +1207,16 @@ int radeon_suspend_kms(struct drm_device *dev, pm_message_t state)
 
         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);
diff --git a/drivers/gpu/drm/radeon/radeon_fence.c b/drivers/gpu/drm/radeon/radeon_fence.c
index a9b0fa5608eb..34356252567a 100644
--- 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 radeon_device *rdev, int ring)
  * 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 radeon_device *rdev)
  */
 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;
diff --git a/drivers/gpu/drm/radeon/radeon_pm.c b/drivers/gpu/drm/radeon/radeon_pm.c
index aa14dbb7e4fb..0bfa656aa87d 100644
--- 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(struct radeon_device *rdev)
 
 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 radeon_device *rdev)
         /* 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);