drm/radeon: clear reset flags if engines are idle

Fixes a hard lock in the gpu reset code after the
rework for DMA support (0ecebb9e
"drm/radeon: switch to a finer grained reset for evergreen")
due to not bailing before the MC shutdown if the relevant engines
are idle.

Discussion:
http://lists.freedesktop.org/archives/dri-devel/2013-January/032985.htmlReported-by: Eldad Zack <eldad@fogrefinery.com>
Tested-by: Eldad Zack <eldad@fogrefinery.com>
Acked-by: Paul Menzel <paulepanter@users.sourceforge.net>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/evergreen.c

@@ -2401,6 +2401,12 @@ static int evergreen_gpu_soft_reset(struct radeon_device *rdev, u32 reset_mask)
 {
 	struct evergreen_mc_save save;
 
+	if (!(RREG32(GRBM_STATUS) & GUI_ACTIVE))
+		reset_mask &= ~(RADEON_RESET_GFX | RADEON_RESET_COMPUTE);
+
+	if (RREG32(DMA_STATUS_REG) & DMA_IDLE)
+		reset_mask &= ~RADEON_RESET_DMA;
+
 	if (reset_mask == 0)
 		return 0;
 

drivers/gpu/drm/radeon/ni.c

@@ -1409,6 +1409,12 @@ static int cayman_gpu_soft_reset(struct radeon_device *rdev, u32 reset_mask)
 {
 	struct evergreen_mc_save save;
 
+	if (!(RREG32(GRBM_STATUS) & GUI_ACTIVE))
+		reset_mask &= ~(RADEON_RESET_GFX | RADEON_RESET_COMPUTE);
+
+	if (RREG32(DMA_STATUS_REG) & DMA_IDLE)
+		reset_mask &= ~RADEON_RESET_DMA;
+
 	if (reset_mask == 0)
 		return 0;
 

drivers/gpu/drm/radeon/r600.c

@@ -1378,6 +1378,12 @@ static int r600_gpu_soft_reset(struct radeon_device *rdev, u32 reset_mask)
 {
 	struct rv515_mc_save save;
 
+	if (!(RREG32(GRBM_STATUS) & GUI_ACTIVE))
+		reset_mask &= ~(RADEON_RESET_GFX | RADEON_RESET_COMPUTE);
+
+	if (RREG32(DMA_STATUS_REG) & DMA_IDLE)
+		reset_mask &= ~RADEON_RESET_DMA;
+
 	if (reset_mask == 0)
 		return 0;
 

drivers/gpu/drm/radeon/si.c

@@ -2215,6 +2215,12 @@ static int si_gpu_soft_reset(struct radeon_device *rdev, u32 reset_mask)
 {
 	struct evergreen_mc_save save;
 
+	if (!(RREG32(GRBM_STATUS) & GUI_ACTIVE))
+		reset_mask &= ~(RADEON_RESET_GFX | RADEON_RESET_COMPUTE);
+
+	if (RREG32(DMA_STATUS_REG) & DMA_IDLE)
+		reset_mask &= ~RADEON_RESET_DMA;
+
 	if (reset_mask == 0)
 		return 0;