[PATCH] drm/amdgpu/sdma: don't actually disable any SDMA rings via debugfs

[Alex Deucher]

We can disable various queues via debugfs for IGT testing, but in
doing so, we race with the kernel for VM updates or buffer moves.

Fixes: d2e3961ae371 ("drm/amdgpu: add amdgpu_sdma_sched_mask debugfs")
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c | 25 ++++--------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c
index 8b8a04138711c..4f98d4920f5cf 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sdma.c
@@ -350,9 +350,8 @@ int amdgpu_sdma_ras_sw_init(struct amdgpu_device *adev)
 static int amdgpu_debugfs_sdma_sched_mask_set(void *data, u64 val)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)data;
-	u64 i, num_ring;
+	u64 num_ring;
 	u64 mask = 0;
-	struct amdgpu_ring *ring, *page = NULL;
 
 	if (!adev)
 		return -ENODEV;
@@ -372,25 +371,9 @@ static int amdgpu_debugfs_sdma_sched_mask_set(void *data, u64 val)
 
 	if ((val & mask) == 0)
 		return -EINVAL;
-
-	for (i = 0; i < adev->sdma.num_instances; ++i) {
-		ring = &adev->sdma.instance[i].ring;
-		if (adev->sdma.has_page_queue)
-			page = &adev->sdma.instance[i].page;
-		if (val & BIT_ULL(i * num_ring))
-			ring->sched.ready = true;
-		else
-			ring->sched.ready = false;
-
-		if (page) {
-			if (val & BIT_ULL(i * num_ring + 1))
-				page->sched.ready = true;
-			else
-				page->sched.ready = false;
-		}
-	}
-	/* publish sched.ready flag update effective immediately across smp */
-	smp_rmb();
+	/* Just return success here. We can't disable any rings otherwise
+	 * we race with vm udpates or buffer ops.
+	 */
 	return 0;
 }
 
-- 
2.50.0