diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
index fc8da5fed779..3c92dacbc24a 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
@@ -6590,8 +6590,12 @@ static int gfx_v10_0_kiq_init_register(struct amdgpu_ring *ring)
 	if (ring->use_doorbell) {
 		WREG32_SOC15(GC, 0, mmCP_MEC_DOORBELL_RANGE_LOWER,
 			(adev->doorbell_index.kiq * 2) << 2);
+		/* If GC has entered CGPG, ringing doorbell > first page doesn't
+		 * wakeup GC. Enlarge CP_MEC_DOORBELL_RANGE_UPPER to workaround
+		 * this issue.
+		 */
 		WREG32_SOC15(GC, 0, mmCP_MEC_DOORBELL_RANGE_UPPER,
-			(adev->doorbell_index.userqueue_end * 2) << 2);
+			(adev->doorbell.size - 4));
 	}
 
 	WREG32_SOC15(GC, 0, mmCP_HQD_PQ_DOORBELL_CONTROL,