diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
index 508efc8ceb66b3097826084cf87b120ac1c3bdfc..99a5b3b92e8edbd9729493e881c8832da6499e95 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
@@ -3583,7 +3583,7 @@ static void gfx_v9_0_ring_set_wptr_gfx(struct amdgpu_ring *ring)
 static void gfx_v9_0_ring_emit_hdp_flush(struct amdgpu_ring *ring)
 {
 	u32 ref_and_mask, reg_mem_engine;
-	struct nbio_hdp_flush_reg *nbio_hf_reg;
+	const struct nbio_hdp_flush_reg *nbio_hf_reg;
 
 	if (ring->adev->flags & AMD_IS_APU)
 		nbio_hf_reg = &nbio_v7_0_hdp_flush_reg;
diff --git a/drivers/gpu/drm/amd/amdgpu/nbio_v6_1.c b/drivers/gpu/drm/amd/amdgpu/nbio_v6_1.c
index 7723d7bccb96484d74cc7cf61a6cdb3efc3083e7..904a1bab9b9f38de35590829d742a2969e3ec979 100644
--- a/drivers/gpu/drm/amd/amdgpu/nbio_v6_1.c
+++ b/drivers/gpu/drm/amd/amdgpu/nbio_v6_1.c
@@ -215,32 +215,28 @@ void nbio_v6_1_get_clockgating_state(struct amdgpu_device *adev, u32 *flags)
 		*flags |= AMD_CG_SUPPORT_BIF_LS;
 }
 
-struct nbio_hdp_flush_reg nbio_v6_1_hdp_flush_reg;
+const struct nbio_hdp_flush_reg nbio_v6_1_hdp_flush_reg = {
+	.hdp_flush_req_offset = SOC15_REG_OFFSET(NBIO, 0, mmBIF_BX_PF0_GPU_HDP_FLUSH_REQ),
+	.hdp_flush_done_offset = SOC15_REG_OFFSET(NBIO, 0, mmBIF_BX_PF0_GPU_HDP_FLUSH_DONE),
+	.ref_and_mask_cp0 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP0_MASK,
+	.ref_and_mask_cp1 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP1_MASK,
+	.ref_and_mask_cp2 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP2_MASK,
+	.ref_and_mask_cp3 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP3_MASK,
+	.ref_and_mask_cp4 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP4_MASK,
+	.ref_and_mask_cp5 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP5_MASK,
+	.ref_and_mask_cp6 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP6_MASK,
+	.ref_and_mask_cp7 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP7_MASK,
+	.ref_and_mask_cp8 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP8_MASK,
+	.ref_and_mask_cp9 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP9_MASK,
+	.ref_and_mask_sdma0 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__SDMA0_MASK,
+	.ref_and_mask_sdma1 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__SDMA1_MASK
+};
+
 const struct nbio_pcie_index_data nbio_v6_1_pcie_index_data = {
 	.index_offset = SOC15_REG_OFFSET(NBIO, 0, mmPCIE_INDEX),
 	.data_offset = SOC15_REG_OFFSET(NBIO, 0, mmPCIE_DATA),
 };
 
-int nbio_v6_1_init(struct amdgpu_device *adev)
-{
-	nbio_v6_1_hdp_flush_reg.hdp_flush_req_offset = SOC15_REG_OFFSET(NBIO, 0, mmBIF_BX_PF0_GPU_HDP_FLUSH_REQ);
-	nbio_v6_1_hdp_flush_reg.hdp_flush_done_offset = SOC15_REG_OFFSET(NBIO, 0, mmBIF_BX_PF0_GPU_HDP_FLUSH_DONE);
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp0 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP0_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp1 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP1_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp2 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP2_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp3 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP3_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp4 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP4_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp5 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP5_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp6 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP6_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp7 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP7_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp8 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP8_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_cp9 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__CP9_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_sdma0 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__SDMA0_MASK;
-	nbio_v6_1_hdp_flush_reg.ref_and_mask_sdma1 = BIF_BX_PF0_GPU_HDP_FLUSH_DONE__SDMA1_MASK;
-
-	return 0;
-}
-
 void nbio_v6_1_detect_hw_virt(struct amdgpu_device *adev)
 {
 	uint32_t reg;
diff --git a/drivers/gpu/drm/amd/amdgpu/nbio_v6_1.h b/drivers/gpu/drm/amd/amdgpu/nbio_v6_1.h
index c5ca1e47763cb387c66d3d89d15850b13ddbc95d..14ca8d45a46c6cb059eaeb2ccad6ca365e93a0bd 100644
--- a/drivers/gpu/drm/amd/amdgpu/nbio_v6_1.h
+++ b/drivers/gpu/drm/amd/amdgpu/nbio_v6_1.h
@@ -26,7 +26,7 @@
 
 #include "soc15_common.h"
 
-extern struct nbio_hdp_flush_reg nbio_v6_1_hdp_flush_reg;
+extern const struct nbio_hdp_flush_reg nbio_v6_1_hdp_flush_reg;
 extern const struct nbio_pcie_index_data nbio_v6_1_pcie_index_data;
 int nbio_v6_1_init(struct amdgpu_device *adev);
 u32 nbio_v6_1_get_atombios_scratch_regs(struct amdgpu_device *adev,
diff --git a/drivers/gpu/drm/amd/amdgpu/nbio_v7_0.c b/drivers/gpu/drm/amd/amdgpu/nbio_v7_0.c
index b932b780dd329ba7c298263449f05fc7787ce441..f802b973410a8b665f73c70417ca7237e9023beb 100644
--- a/drivers/gpu/drm/amd/amdgpu/nbio_v7_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/nbio_v7_0.c
@@ -185,28 +185,24 @@ void nbio_v7_0_ih_control(struct amdgpu_device *adev)
 	WREG32_SOC15(NBIO, 0, mmINTERRUPT_CNTL, interrupt_cntl);
 }
 
-struct nbio_hdp_flush_reg nbio_v7_0_hdp_flush_reg;
+const struct nbio_hdp_flush_reg nbio_v7_0_hdp_flush_reg = {
+	.hdp_flush_req_offset = SOC15_REG_OFFSET(NBIO, 0, mmGPU_HDP_FLUSH_REQ),
+	.hdp_flush_done_offset = SOC15_REG_OFFSET(NBIO, 0, mmGPU_HDP_FLUSH_DONE),
+	.ref_and_mask_cp0 = GPU_HDP_FLUSH_DONE__CP0_MASK,
+	.ref_and_mask_cp1 = GPU_HDP_FLUSH_DONE__CP1_MASK,
+	.ref_and_mask_cp2 = GPU_HDP_FLUSH_DONE__CP2_MASK,
+	.ref_and_mask_cp3 = GPU_HDP_FLUSH_DONE__CP3_MASK,
+	.ref_and_mask_cp4 = GPU_HDP_FLUSH_DONE__CP4_MASK,
+	.ref_and_mask_cp5 = GPU_HDP_FLUSH_DONE__CP5_MASK,
+	.ref_and_mask_cp6 = GPU_HDP_FLUSH_DONE__CP6_MASK,
+	.ref_and_mask_cp7 = GPU_HDP_FLUSH_DONE__CP7_MASK,
+	.ref_and_mask_cp8 = GPU_HDP_FLUSH_DONE__CP8_MASK,
+	.ref_and_mask_cp9 = GPU_HDP_FLUSH_DONE__CP9_MASK,
+	.ref_and_mask_sdma0 = GPU_HDP_FLUSH_DONE__SDMA0_MASK,
+	.ref_and_mask_sdma1 = GPU_HDP_FLUSH_DONE__SDMA1_MASK,
+};
+
 const struct nbio_pcie_index_data nbio_v7_0_pcie_index_data = {
 	.index_offset = SOC15_REG_OFFSET(NBIO, 0, mmPCIE_INDEX2),
 	.data_offset = SOC15_REG_OFFSET(NBIO, 0, mmPCIE_DATA2)
 };
-
-int nbio_v7_0_init(struct amdgpu_device *adev)
-{
-	nbio_v7_0_hdp_flush_reg.hdp_flush_req_offset = SOC15_REG_OFFSET(NBIO, 0, mmGPU_HDP_FLUSH_REQ);
-	nbio_v7_0_hdp_flush_reg.hdp_flush_done_offset = SOC15_REG_OFFSET(NBIO, 0, mmGPU_HDP_FLUSH_DONE);
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp0 = GPU_HDP_FLUSH_DONE__CP0_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp1 = GPU_HDP_FLUSH_DONE__CP1_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp2 = GPU_HDP_FLUSH_DONE__CP2_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp3 = GPU_HDP_FLUSH_DONE__CP3_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp4 = GPU_HDP_FLUSH_DONE__CP4_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp5 = GPU_HDP_FLUSH_DONE__CP5_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp6 = GPU_HDP_FLUSH_DONE__CP6_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp7 = GPU_HDP_FLUSH_DONE__CP7_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp8 = GPU_HDP_FLUSH_DONE__CP8_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_cp9 = GPU_HDP_FLUSH_DONE__CP9_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_sdma0 = GPU_HDP_FLUSH_DONE__SDMA0_MASK;
-	nbio_v7_0_hdp_flush_reg.ref_and_mask_sdma1 = GPU_HDP_FLUSH_DONE__SDMA1_MASK;
-
-	return 0;
-}
diff --git a/drivers/gpu/drm/amd/amdgpu/nbio_v7_0.h b/drivers/gpu/drm/amd/amdgpu/nbio_v7_0.h
index 21bad0098bf6e1b9fcf629f2e0aeb601b52b7153..df8fa90f40d7f6a4ed8ef05611233f7171ae44ee 100644
--- a/drivers/gpu/drm/amd/amdgpu/nbio_v7_0.h
+++ b/drivers/gpu/drm/amd/amdgpu/nbio_v7_0.h
@@ -26,7 +26,7 @@
 
 #include "soc15_common.h"
 
-extern struct nbio_hdp_flush_reg nbio_v7_0_hdp_flush_reg;
+extern const struct nbio_hdp_flush_reg nbio_v7_0_hdp_flush_reg;
 extern const struct nbio_pcie_index_data nbio_v7_0_pcie_index_data;
 int nbio_v7_0_init(struct amdgpu_device *adev);
 u32 nbio_v7_0_get_atombios_scratch_regs(struct amdgpu_device *adev,
diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
index c26d205ff3bf4d632cdd0ff574e40d3adfd79f97..46009db3d195cb56b4c204d6e83cc451b5cd593a 100644
--- a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
@@ -371,7 +371,7 @@ static void sdma_v4_0_ring_emit_ib(struct amdgpu_ring *ring,
 static void sdma_v4_0_ring_emit_hdp_flush(struct amdgpu_ring *ring)
 {
 	u32 ref_and_mask = 0;
-	struct nbio_hdp_flush_reg *nbio_hf_reg;
+	const struct nbio_hdp_flush_reg *nbio_hf_reg;
 
 	if (ring->adev->flags & AMD_IS_APU)
 		nbio_hf_reg = &nbio_v7_0_hdp_flush_reg;
diff --git a/drivers/gpu/drm/amd/amdgpu/soc15.c b/drivers/gpu/drm/amd/amdgpu/soc15.c
index dd5cbf37abc4651a9da7eabc61d53a3d032a9da5..1c006ba9d826ac20b065417b6f6ec8b5fcf3f967 100644
--- a/drivers/gpu/drm/amd/amdgpu/soc15.c
+++ b/drivers/gpu/drm/amd/amdgpu/soc15.c
@@ -604,21 +604,6 @@ static int soc15_common_early_init(void *handle)
 		(amdgpu_ip_block_mask & (1 << AMD_IP_BLOCK_TYPE_PSP)))
 		psp_enabled = true;
 
-	/*
-	 * nbio need be used for both sdma and gfx9, but only
-	 * initializes once
-	 */
-	switch(adev->asic_type) {
-	case CHIP_VEGA10:
-		nbio_v6_1_init(adev);
-		break;
-	case CHIP_RAVEN:
-		nbio_v7_0_init(adev);
-		break;
-	default:
-		return -EINVAL;
-	}
-
 	adev->rev_id = soc15_get_rev_id(adev);
 	adev->external_rev_id = 0xFF;
 	switch (adev->asic_type) {