[PATCH] drm/amdgpu/gmc9: give more chance for tlb flush if failed(v2)

[Emily.Deng@xxxxxxx (Emily Deng)]

under SR-IOV sometimes CPU based tlb flush would timeout within
the given 100ms period, instead let it fail and continue we can
give it more chance to repeat the tlb flush on the failed VMHUB

this could fix the massive "Timeout waiting for VM flush ACK"
error during vk_encoder test.

v2:refine the code

Signed-off-by: Monk Liu <Monk.Liu at amd.com>
Signed-off-by: Emily Deng <Emily.Deng at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 50 ++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
index 503070f..44602d4 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
@@ -328,7 +328,8 @@ static void gmc_v9_0_flush_gpu_tlb(struct amdgpu_device *adev,
 {
 	/* Use register 17 for GART */
 	const unsigned eng = 17;
-	unsigned i, j;
+	unsigned retry = 3;
+	unsigned i, j, k;
 
 	spin_lock(&adev->gmc.invalidate_lock);
 
@@ -336,31 +337,36 @@ static void gmc_v9_0_flush_gpu_tlb(struct amdgpu_device *adev,
 		struct amdgpu_vmhub *hub = &adev->vmhub[i];
 		u32 tmp = gmc_v9_0_get_invalidate_req(vmid);
 
-		WREG32_NO_KIQ(hub->vm_inv_eng0_req + eng, tmp);
+		for (k = 0; k < retry; ++k) {
 
-		/* Busy wait for ACK.*/
-		for (j = 0; j < 100; j++) {
-			tmp = RREG32_NO_KIQ(hub->vm_inv_eng0_ack + eng);
-			tmp &= 1 << vmid;
-			if (tmp)
+			WREG32_NO_KIQ(hub->vm_inv_eng0_req + eng, tmp);
+
+			/* Busy wait for ACK.*/
+			for (j = 0; j < 100; j++) {
+				tmp = RREG32_NO_KIQ(hub->vm_inv_eng0_ack + eng);
+				tmp &= 1 << vmid;
+				if (tmp)
+					break;
+				cpu_relax();
+			}
+			if (j < 100)
 				break;
-			cpu_relax();
-		}
-		if (j < 100)
-			continue;
-
-		/* Wait for ACK with a delay.*/
-		for (j = 0; j < adev->usec_timeout; j++) {
-			tmp = RREG32_NO_KIQ(hub->vm_inv_eng0_ack + eng);
-			tmp &= 1 << vmid;
-			if (tmp)
+
+			/* Wait for ACK with a delay.*/
+			for (j = 0; j < adev->usec_timeout; j++) {
+				tmp = RREG32_NO_KIQ(hub->vm_inv_eng0_ack + eng);
+				tmp &= 1 << vmid;
+				if (tmp)
+					break;
+				udelay(1);
+			}
+			if (j < adev->usec_timeout)
 				break;
-			udelay(1);
+			if (k == retry)
+				DRM_ERROR("Timeout waiting for VM flush ACK!\n");
+			else
+				DRM_ERROR("Need one more try to write the VMHUB flush request!");
 		}
-		if (j < adev->usec_timeout)
-			continue;
-
-		DRM_ERROR("Timeout waiting for VM flush ACK!\n");
 	}
 
 	spin_unlock(&adev->gmc.invalidate_lock);
-- 
2.7.4