drm/radeon: implement ring saving on reset v4

Try to save whatever is on the rings when
we encounter an lockup.

v2: Fix spelling error. Free saved ring data if reset fails.
    Add documentation for the new functions.
v3: Some more spelling fixes
v4: It doesn't make sense to save anything if all fences
    are signaled

Signed-off-by: Christian König <deathsimple@vodafone.de>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 82 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_ring.c b/drivers/gpu/drm/radeon/radeon_ring.c
index ce8eb9d5af5d..75cbe4641138 100644
--- a/drivers/gpu/drm/radeon/radeon_ring.c
+++ b/drivers/gpu/drm/radeon/radeon_ring.c
@@ -362,6 +362,88 @@ bool radeon_ring_test_lockup(struct radeon_device *rdev, struct radeon_ring *rin
         return false;
 }
 
+/**
+ * radeon_ring_backup - Back up the content of a ring
+ *
+ * @rdev: radeon_device pointer
+ * @ring: the ring we want to back up
+ *
+ * Saves all unprocessed commits from a ring, returns the number of dwords saved.
+ */
+unsigned radeon_ring_backup(struct radeon_device *rdev, struct radeon_ring *ring,
+                            uint32_t **data)
+{
+        unsigned size, ptr, i;
+        int ridx = radeon_ring_index(rdev, ring);
+
+        /* just in case lock the ring */
+        mutex_lock(&rdev->ring_lock);
+        *data = NULL;
+
+        if (ring->ring_obj == NULL || !ring->rptr_save_reg) {
+                mutex_unlock(&rdev->ring_lock);
+                return 0;
+        }
+
+        /* it doesn't make sense to save anything if all fences are signaled */
+        if (!radeon_fence_count_emitted(rdev, ridx)) {
+                mutex_unlock(&rdev->ring_lock);
+                return 0;
+        }
+
+        /* calculate the number of dw on the ring */
+        ptr = RREG32(ring->rptr_save_reg);
+        size = ring->wptr + (ring->ring_size / 4);
+        size -= ptr;
+        size &= ring->ptr_mask;
+        if (size == 0) {
+                mutex_unlock(&rdev->ring_lock);
+                return 0;
+        }
+
+        /* and then save the content of the ring */
+        *data = kmalloc(size * 4, GFP_KERNEL);
+        for (i = 0; i < size; ++i) {
+                (*data)[i] = ring->ring[ptr++];
+                ptr &= ring->ptr_mask;
+        }
+
+        mutex_unlock(&rdev->ring_lock);
+        return size;
+}
+
+/**
+ * radeon_ring_restore - append saved commands to the ring again
+ *
+ * @rdev: radeon_device pointer
+ * @ring: ring to append commands to
+ * @size: number of dwords we want to write
+ * @data: saved commands
+ *
+ * Allocates space on the ring and restore the previously saved commands.
+ */
+int radeon_ring_restore(struct radeon_device *rdev, struct radeon_ring *ring,
+                        unsigned size, uint32_t *data)
+{
+        int i, r;
+
+        if (!size || !data)
+                return 0;
+
+        /* restore the saved ring content */
+        r = radeon_ring_lock(rdev, ring, size);
+        if (r)
+                return r;
+
+        for (i = 0; i < size; ++i) {
+                radeon_ring_write(ring, data[i]);
+        }
+
+        radeon_ring_unlock_commit(rdev, ring);
+        kfree(data);
+        return 0;
+}
+
 int radeon_ring_init(struct radeon_device *rdev, struct radeon_ring *ring, unsigned ring_size,
                      unsigned rptr_offs, unsigned rptr_reg, unsigned wptr_reg,
                      u32 ptr_reg_shift, u32 ptr_reg_mask, u32 nop)