[PATCH] amdgpu/gmc_v9: Warn if SDPIF_MMIO_CNTRL_0 is not set

[Shirish S]

With IOMMU enabled, if SDPIF_MMIO_CNTRL_0 is not set
appropriately the system hangs without any trace
during S3.

To ease debug and to ensure that the failure, if any,
was caused by a race conditions that disabled write access to
SDPIF_MMIO_CNTRL_0 register, warn the user about it.

Signed-off-by: Shirish S <shirish.s at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
index d0645ad3446e..fc2d88dbe828 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
@@ -1546,8 +1546,11 @@ static void gmc_v9_0_init_golden_registers(struct amdgpu_device *adev)
  */
 void gmc_v9_0_restore_registers(struct amdgpu_device *adev)
 {
-	if (adev->asic_type == CHIP_RAVEN)
+	if (adev->asic_type == CHIP_RAVEN) {
 		WREG32_SOC15(DCE, 0, mmDCHUBBUB_SDPIF_MMIO_CNTRL_0, adev->gmc.sdpif_register);
+		WARN_ON(adev->gmc.sdpif_register !=
+			RREG32_SOC15(DCE, 0, mmDCHUBBUB_SDPIF_MMIO_CNTRL_0);
+	}
 }
 
 /**
-- 
2.17.1