[PATCH] drm/amdgpu: Workaround RCC_DEV0_EPF0_STRAP0 access issue for SRIOV

[Rohit Khaire]

Signed-off-by: Rohit Khaire <rohit.khaire at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c b/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
index 7429f30398b9..78cb48bafa4c 100644
--- a/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
+++ b/drivers/gpu/drm/amd/amdgpu/nbio_v2_3.c
@@ -51,8 +51,20 @@ static void nbio_v2_3_remap_hdp_registers(struct amdgpu_device *adev)
 
 static u32 nbio_v2_3_get_rev_id(struct amdgpu_device *adev)
 {
-	u32 tmp = RREG32_SOC15(NBIO, 0, mmRCC_DEV0_EPF0_STRAP0);
+	u32 tmp;
+
+	if (amdgpu_sriov_vf(adev)) {
+		/* workaround on rev_id for sriov
+		 * guest vm gets 0xffffffff when reading RCC_DEV0_EPF0_STRAP0,
+		 * as a consequence, the rev_id and external_rev_id are wrong.
+		 *
+		 * workaround it by hardcoding the rev_id to 0,
+		 *    (which is the default value)
+		 */
+		return adev->pdev->revision;
+	}
 
+	tmp = RREG32_SOC15(NBIO, 0, mmRCC_DEV0_EPF0_STRAP0);
 	tmp &= RCC_DEV0_EPF0_STRAP0__STRAP_ATI_REV_ID_DEV0_F0_MASK;
 	tmp >>= RCC_DEV0_EPF0_STRAP0__STRAP_ATI_REV_ID_DEV0_F0__SHIFT;
 
-- 
2.17.1