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* [PATCH] drm/amdgpu:fix IH overflow on Tonga
@ 2021-01-05  7:51 ` Defang Bo
  0 siblings, 0 replies; 3+ messages in thread
From: Defang Bo @ 2021-01-05  7:51 UTC (permalink / raw)
  To: airlied, daniel
  Cc: christian.koenig, alexander.deucher, amd-gfx, dri-devel,
	linux-kernel, Defang Bo

Similar to commit <b82175750131>("drm/amdgpu: fix IH overflow on Vega10 v2").
When an ring buffer overflow happens the appropriate bit is set in the WPTR
register which is also written back to memory. But clearing the bit in the
WPTR doesn't trigger another memory writeback.

So what can happen is that we end up processing the buffer overflow over and
over again because the bit is never cleared. Resulting in a random system
lockup because of an infinite loop in an interrupt handler.

Signed-off-by: Defang Bo <bodefang@126.com>
---
 drivers/gpu/drm/amd/amdgpu/tonga_ih.c | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/tonga_ih.c b/drivers/gpu/drm/amd/amdgpu/tonga_ih.c
index e40140bf6699..9c5947976717 100644
--- a/drivers/gpu/drm/amd/amdgpu/tonga_ih.c
+++ b/drivers/gpu/drm/amd/amdgpu/tonga_ih.c
@@ -195,19 +195,28 @@ static u32 tonga_ih_get_wptr(struct amdgpu_device *adev,
 
 	wptr = le32_to_cpu(*ih->wptr_cpu);
 
-	if (REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW)) {
-		wptr = REG_SET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW, 0);
-		/* When a ring buffer overflow happen start parsing interrupt
-		 * from the last not overwritten vector (wptr + 16). Hopefully
-		 * this should allow us to catchup.
-		 */
-		dev_warn(adev->dev, "IH ring buffer overflow (0x%08X, 0x%08X, 0x%08X)\n",
-			 wptr, ih->rptr, (wptr + 16) & ih->ptr_mask);
-		ih->rptr = (wptr + 16) & ih->ptr_mask;
-		tmp = RREG32(mmIH_RB_CNTL);
-		tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, WPTR_OVERFLOW_CLEAR, 1);
-		WREG32(mmIH_RB_CNTL, tmp);
-	}
+	if (!REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW))
+		goto out;
+
+	wptr = RREG32(mmIH_RB_CNTL);
+
+	if (!REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW))
+		goto out;
+
+	wptr = REG_SET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW, 0);
+
+	/* When a ring buffer overflow happen start parsing interrupt
+	 * from the last not overwritten vector (wptr + 16). Hopefully
+	 * this should allow us to catchup.
+	 */
+	dev_warn(adev->dev, "IH ring buffer overflow (0x%08X, 0x%08X, 0x%08X)\n",
+		wptr, ih->rptr, (wptr + 16) & ih->ptr_mask);
+	ih->rptr = (wptr + 16) & ih->ptr_mask;
+	tmp = RREG32(mmIH_RB_CNTL);
+	tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, WPTR_OVERFLOW_CLEAR, 1);
+	WREG32(mmIH_RB_CNTL, tmp);
+
+out:
 	return (wptr & ih->ptr_mask);
 }
 
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* [PATCH] drm/amdgpu:fix IH overflow on Tonga
@ 2021-01-05  7:51 ` Defang Bo
  0 siblings, 0 replies; 3+ messages in thread
From: Defang Bo @ 2021-01-05  7:51 UTC (permalink / raw)
  To: airlied, daniel
  Cc: amd-gfx, linux-kernel, dri-devel, Defang Bo, alexander.deucher,
	christian.koenig

Similar to commit <b82175750131>("drm/amdgpu: fix IH overflow on Vega10 v2").
When an ring buffer overflow happens the appropriate bit is set in the WPTR
register which is also written back to memory. But clearing the bit in the
WPTR doesn't trigger another memory writeback.

So what can happen is that we end up processing the buffer overflow over and
over again because the bit is never cleared. Resulting in a random system
lockup because of an infinite loop in an interrupt handler.

Signed-off-by: Defang Bo <bodefang@126.com>
---
 drivers/gpu/drm/amd/amdgpu/tonga_ih.c | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/tonga_ih.c b/drivers/gpu/drm/amd/amdgpu/tonga_ih.c
index e40140bf6699..9c5947976717 100644
--- a/drivers/gpu/drm/amd/amdgpu/tonga_ih.c
+++ b/drivers/gpu/drm/amd/amdgpu/tonga_ih.c
@@ -195,19 +195,28 @@ static u32 tonga_ih_get_wptr(struct amdgpu_device *adev,
 
 	wptr = le32_to_cpu(*ih->wptr_cpu);
 
-	if (REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW)) {
-		wptr = REG_SET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW, 0);
-		/* When a ring buffer overflow happen start parsing interrupt
-		 * from the last not overwritten vector (wptr + 16). Hopefully
-		 * this should allow us to catchup.
-		 */
-		dev_warn(adev->dev, "IH ring buffer overflow (0x%08X, 0x%08X, 0x%08X)\n",
-			 wptr, ih->rptr, (wptr + 16) & ih->ptr_mask);
-		ih->rptr = (wptr + 16) & ih->ptr_mask;
-		tmp = RREG32(mmIH_RB_CNTL);
-		tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, WPTR_OVERFLOW_CLEAR, 1);
-		WREG32(mmIH_RB_CNTL, tmp);
-	}
+	if (!REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW))
+		goto out;
+
+	wptr = RREG32(mmIH_RB_CNTL);
+
+	if (!REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW))
+		goto out;
+
+	wptr = REG_SET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW, 0);
+
+	/* When a ring buffer overflow happen start parsing interrupt
+	 * from the last not overwritten vector (wptr + 16). Hopefully
+	 * this should allow us to catchup.
+	 */
+	dev_warn(adev->dev, "IH ring buffer overflow (0x%08X, 0x%08X, 0x%08X)\n",
+		wptr, ih->rptr, (wptr + 16) & ih->ptr_mask);
+	ih->rptr = (wptr + 16) & ih->ptr_mask;
+	tmp = RREG32(mmIH_RB_CNTL);
+	tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, WPTR_OVERFLOW_CLEAR, 1);
+	WREG32(mmIH_RB_CNTL, tmp);
+
+out:
 	return (wptr & ih->ptr_mask);
 }
 
-- 
2.7.4

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

^ permalink raw reply related	[flat|nested] 3+ messages in thread
* [PATCH] drm/amdgpu:fix IH overflow on Tonga
@ 2021-01-05  7:51 ` Defang Bo
  0 siblings, 0 replies; 3+ messages in thread
From: Defang Bo @ 2021-01-05  7:51 UTC (permalink / raw)
  To: airlied, daniel
  Cc: amd-gfx, linux-kernel, dri-devel, Defang Bo, alexander.deucher,
	christian.koenig

Similar to commit <b82175750131>("drm/amdgpu: fix IH overflow on Vega10 v2").
When an ring buffer overflow happens the appropriate bit is set in the WPTR
register which is also written back to memory. But clearing the bit in the
WPTR doesn't trigger another memory writeback.

So what can happen is that we end up processing the buffer overflow over and
over again because the bit is never cleared. Resulting in a random system
lockup because of an infinite loop in an interrupt handler.

Signed-off-by: Defang Bo <bodefang@126.com>
---
 drivers/gpu/drm/amd/amdgpu/tonga_ih.c | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/tonga_ih.c b/drivers/gpu/drm/amd/amdgpu/tonga_ih.c
index e40140bf6699..9c5947976717 100644
--- a/drivers/gpu/drm/amd/amdgpu/tonga_ih.c
+++ b/drivers/gpu/drm/amd/amdgpu/tonga_ih.c
@@ -195,19 +195,28 @@ static u32 tonga_ih_get_wptr(struct amdgpu_device *adev,
 
 	wptr = le32_to_cpu(*ih->wptr_cpu);
 
-	if (REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW)) {
-		wptr = REG_SET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW, 0);
-		/* When a ring buffer overflow happen start parsing interrupt
-		 * from the last not overwritten vector (wptr + 16). Hopefully
-		 * this should allow us to catchup.
-		 */
-		dev_warn(adev->dev, "IH ring buffer overflow (0x%08X, 0x%08X, 0x%08X)\n",
-			 wptr, ih->rptr, (wptr + 16) & ih->ptr_mask);
-		ih->rptr = (wptr + 16) & ih->ptr_mask;
-		tmp = RREG32(mmIH_RB_CNTL);
-		tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, WPTR_OVERFLOW_CLEAR, 1);
-		WREG32(mmIH_RB_CNTL, tmp);
-	}
+	if (!REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW))
+		goto out;
+
+	wptr = RREG32(mmIH_RB_CNTL);
+
+	if (!REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW))
+		goto out;
+
+	wptr = REG_SET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW, 0);
+
+	/* When a ring buffer overflow happen start parsing interrupt
+	 * from the last not overwritten vector (wptr + 16). Hopefully
+	 * this should allow us to catchup.
+	 */
+	dev_warn(adev->dev, "IH ring buffer overflow (0x%08X, 0x%08X, 0x%08X)\n",
+		wptr, ih->rptr, (wptr + 16) & ih->ptr_mask);
+	ih->rptr = (wptr + 16) & ih->ptr_mask;
+	tmp = RREG32(mmIH_RB_CNTL);
+	tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, WPTR_OVERFLOW_CLEAR, 1);
+	WREG32(mmIH_RB_CNTL, tmp);
+
+out:
 	return (wptr & ih->ptr_mask);
 }
 
-- 
2.7.4

_______________________________________________
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx

^ permalink raw reply related	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-01-05  8:23 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2021-01-05  7:51 [PATCH] drm/amdgpu:fix IH overflow on Tonga Defang Bo
2021-01-05  7:51 ` Defang Bo
2021-01-05  7:51 ` Defang Bo

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