[PATCH] drm/radeon: Don't read from CP ring write pointer registers.

[Michel Dänzer]

From: Michel Dänzer <michel.daenzer at amd.com>

Apparently this doesn't always work reliably, e.g. at resume time.

Just initialize to 0, so the ring is considered empty.

Tested with hibernation on Sumo and Cayman cards.

Should fix https://bugs.launchpad.net/ubuntu/+source/linux/+bug/820746/ .

Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
---
 drivers/gpu/drm/radeon/evergreen.c |    4 ++--
 drivers/gpu/drm/radeon/ni.c        |   12 ++++++------
 drivers/gpu/drm/radeon/r100.c      |    6 ++----
 drivers/gpu/drm/radeon/r600.c      |    4 ++--
 4 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index 15bd047..f2bd90a 100644
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -1378,7 +1378,8 @@ int evergreen_cp_resume(struct radeon_device *rdev)
 	/* Initialize the ring buffer's read and write pointers */
 	WREG32(CP_RB_CNTL, tmp | RB_RPTR_WR_ENA);
 	WREG32(CP_RB_RPTR_WR, 0);
-	WREG32(CP_RB_WPTR, 0);
+	rdev->cp.wptr = 0;
+	WREG32(CP_RB_WPTR, rdev->cp.wptr);
 
 	/* set the wb address wether it's enabled or not */
 	WREG32(CP_RB_RPTR_ADDR,
@@ -1403,7 +1404,6 @@ int evergreen_cp_resume(struct radeon_device *rdev)
 	WREG32(CP_DEBUG, (1 << 27) | (1 << 28));
 
 	rdev->cp.rptr = RREG32(CP_RB_RPTR);
-	rdev->cp.wptr = RREG32(CP_RB_WPTR);
 
 	evergreen_cp_start(rdev);
 	rdev->cp.ready = true;
diff --git a/drivers/gpu/drm/radeon/ni.c b/drivers/gpu/drm/radeon/ni.c
index 559dbd4..e3489ee 100644
--- a/drivers/gpu/drm/radeon/ni.c
+++ b/drivers/gpu/drm/radeon/ni.c
@@ -1182,7 +1182,8 @@ int cayman_cp_resume(struct radeon_device *rdev)
 
 	/* Initialize the ring buffer's read and write pointers */
 	WREG32(CP_RB0_CNTL, tmp | RB_RPTR_WR_ENA);
-	WREG32(CP_RB0_WPTR, 0);
+	rdev->cp.wptr = 0;
+	WREG32(CP_RB0_WPTR, rdev->cp.wptr);
 
 	/* set the wb address wether it's enabled or not */
 	WREG32(CP_RB0_RPTR_ADDR, (rdev->wb.gpu_addr + RADEON_WB_CP_RPTR_OFFSET) & 0xFFFFFFFC);
@@ -1202,7 +1203,6 @@ int cayman_cp_resume(struct radeon_device *rdev)
 	WREG32(CP_RB0_BASE, rdev->cp.gpu_addr >> 8);
 
 	rdev->cp.rptr = RREG32(CP_RB0_RPTR);
-	rdev->cp.wptr = RREG32(CP_RB0_WPTR);
 
 	/* ring1  - compute only */
 	/* Set ring buffer size */
@@ -1215,7 +1215,8 @@ int cayman_cp_resume(struct radeon_device *rdev)
 
 	/* Initialize the ring buffer's read and write pointers */
 	WREG32(CP_RB1_CNTL, tmp | RB_RPTR_WR_ENA);
-	WREG32(CP_RB1_WPTR, 0);
+	rdev->cp1.wptr = 0;
+	WREG32(CP_RB1_WPTR, rdev->cp1.wptr);
 
 	/* set the wb address wether it's enabled or not */
 	WREG32(CP_RB1_RPTR_ADDR, (rdev->wb.gpu_addr + RADEON_WB_CP1_RPTR_OFFSET) & 0xFFFFFFFC);
@@ -1227,7 +1228,6 @@ int cayman_cp_resume(struct radeon_device *rdev)
 	WREG32(CP_RB1_BASE, rdev->cp1.gpu_addr >> 8);
 
 	rdev->cp1.rptr = RREG32(CP_RB1_RPTR);
-	rdev->cp1.wptr = RREG32(CP_RB1_WPTR);
 
 	/* ring2 - compute only */
 	/* Set ring buffer size */
@@ -1240,7 +1240,8 @@ int cayman_cp_resume(struct radeon_device *rdev)
 
 	/* Initialize the ring buffer's read and write pointers */
 	WREG32(CP_RB2_CNTL, tmp | RB_RPTR_WR_ENA);
-	WREG32(CP_RB2_WPTR, 0);
+	rdev->cp2.wptr = 0;
+	WREG32(CP_RB2_WPTR, rdev->cp2.wptr);
 
 	/* set the wb address wether it's enabled or not */
 	WREG32(CP_RB2_RPTR_ADDR, (rdev->wb.gpu_addr + RADEON_WB_CP2_RPTR_OFFSET) & 0xFFFFFFFC);
@@ -1252,7 +1253,6 @@ int cayman_cp_resume(struct radeon_device *rdev)
 	WREG32(CP_RB2_BASE, rdev->cp2.gpu_addr >> 8);
 
 	rdev->cp2.rptr = RREG32(CP_RB2_RPTR);
-	rdev->cp2.wptr = RREG32(CP_RB2_WPTR);
 
 	/* start the rings */
 	cayman_cp_start(rdev);
diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index f2204cb..11e44a3 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -990,7 +990,8 @@ int r100_cp_init(struct radeon_device *rdev, unsigned ring_size)
 	/* Force read & write ptr to 0 */
 	WREG32(RADEON_CP_RB_CNTL, tmp | RADEON_RB_RPTR_WR_ENA | RADEON_RB_NO_UPDATE);
 	WREG32(RADEON_CP_RB_RPTR_WR, 0);
-	WREG32(RADEON_CP_RB_WPTR, 0);
+	rdev->cp.wptr = 0;
+	WREG32(RADEON_CP_RB_WPTR, rdev->cp.wptr);
 
 	/* set the wb address whether it's enabled or not */
 	WREG32(R_00070C_CP_RB_RPTR_ADDR,
@@ -1007,9 +1008,6 @@ int r100_cp_init(struct radeon_device *rdev, unsigned ring_size)
 	WREG32(RADEON_CP_RB_CNTL, tmp);
 	udelay(10);
 	rdev->cp.rptr = RREG32(RADEON_CP_RB_RPTR);
-	rdev->cp.wptr = RREG32(RADEON_CP_RB_WPTR);
-	/* protect against crazy HW on resume */
-	rdev->cp.wptr &= rdev->cp.ptr_mask;
 	/* Set cp mode to bus mastering & enable cp*/
 	WREG32(RADEON_CP_CSQ_MODE,
 	       REG_SET(RADEON_INDIRECT2_START, indirect2_start) |
diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index bc54b26..8ca098d 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -2208,7 +2208,8 @@ int r600_cp_resume(struct radeon_device *rdev)
 	/* Initialize the ring buffer's read and write pointers */
 	WREG32(CP_RB_CNTL, tmp | RB_RPTR_WR_ENA);
 	WREG32(CP_RB_RPTR_WR, 0);
-	WREG32(CP_RB_WPTR, 0);
+	rdev->cp.wptr = 0;
+	WREG32(CP_RB_WPTR, rdev->cp.wptr);
 
 	/* set the wb address whether it's enabled or not */
 	WREG32(CP_RB_RPTR_ADDR,
@@ -2233,7 +2234,6 @@ int r600_cp_resume(struct radeon_device *rdev)
 	WREG32(CP_DEBUG, (1 << 27) | (1 << 28));
 
 	rdev->cp.rptr = RREG32(CP_RB_RPTR);
-	rdev->cp.wptr = RREG32(CP_RB_WPTR);
 
 	r600_cp_start(rdev);
 	rdev->cp.ready = true;
-- 
1.7.5.4