Merge branch 'drm-fixes-4.5' of git://people.freedesktop.org/~agd5f/linux into drm-fixes

- fix and enable iceland/topaz support
- handle WC on platforms that don't support it

* 'drm-fixes-4.5' of git://people.freedesktop.org/~agd5f/linux:
  drm/amdgpu: disable uvd and vce clockgating on Fiji
  drm/amdgpu: remove exp hardware support from iceland
  drm/amdgpu: load MEC ucode manually on iceland
  drm/amdgpu: don't load MEC2 on topaz
  drm/amdgpu: drop topaz support from gmc8 module
  drm/amdgpu: pull topaz gmc bits into gmc_v7
  drm/amdgpu: The VI specific EXE bit should only apply to GMC v8.0 above
  drm/amdgpu: iceland use CI based MC IP
  drm/amdgpu: move gmc7 support out of CIK dependency
  drm/amdgpu/gfx7: enable cp inst/reg error interrupts
  drm/amdgpu/gfx8: enable cp inst/reg error interrupts
  drm/amdgpu: mask out WC from BO on unsupported arches
  drm/radeon: mask out WC from BO on unsupported arches
  drm: add helper to check for wc memory support
  drm/amdgpu: no need to load MC firmware on fiji

11 files changed, 114 insertions, 59 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/Makefile b/drivers/gpu/drm/amd/amdgpu/Makefile
index 66f729eaf00b..20c9539abc36 100644
--- a/drivers/gpu/drm/amd/amdgpu/Makefile
+++ b/drivers/gpu/drm/amd/amdgpu/Makefile
@@ -25,7 +25,7 @@ amdgpu-y += amdgpu_device.o amdgpu_kms.o \
 	amdgpu_ucode.o amdgpu_bo_list.o amdgpu_ctx.o amdgpu_sync.o
 
 # add asic specific block
-amdgpu-$(CONFIG_DRM_AMDGPU_CIK)+= cik.o gmc_v7_0.o cik_ih.o kv_smc.o kv_dpm.o \
+amdgpu-$(CONFIG_DRM_AMDGPU_CIK)+= cik.o cik_ih.o kv_smc.o kv_dpm.o \
 	ci_smc.o ci_dpm.o dce_v8_0.o gfx_v7_0.o cik_sdma.o uvd_v4_2.o vce_v2_0.o \
 	amdgpu_amdkfd_gfx_v7.o
 
@@ -34,6 +34,7 @@ amdgpu-y += \
 
 # add GMC block
 amdgpu-y += \
+	gmc_v7_0.o \
 	gmc_v8_0.o
 
 # add IH block
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index b5dbbb573491..9c1af8976bef 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -256,11 +256,11 @@ static struct pci_device_id pciidlist[] = {
 	{0x1002, 0x985F, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_MULLINS|AMD_IS_MOBILITY|AMD_IS_APU},
 #endif
 	/* topaz */
-	{0x1002, 0x6900, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ|AMD_EXP_HW_SUPPORT},
-	{0x1002, 0x6901, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ|AMD_EXP_HW_SUPPORT},
-	{0x1002, 0x6902, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ|AMD_EXP_HW_SUPPORT},
-	{0x1002, 0x6903, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ|AMD_EXP_HW_SUPPORT},
-	{0x1002, 0x6907, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ|AMD_EXP_HW_SUPPORT},
+	{0x1002, 0x6900, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ},
+	{0x1002, 0x6901, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ},
+	{0x1002, 0x6902, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ},
+	{0x1002, 0x6903, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ},
+	{0x1002, 0x6907, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TOPAZ},
 	/* tonga */
 	{0x1002, 0x6920, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TONGA},
 	{0x1002, 0x6921, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TONGA},
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index a2a16acee34d..b8fbbd7699e4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -33,6 +33,7 @@
 #include <linux/slab.h>
 #include <drm/drmP.h>
 #include <drm/amdgpu_drm.h>
+#include <drm/drm_cache.h>
 #include "amdgpu.h"
 #include "amdgpu_trace.h"
 
@@ -261,6 +262,13 @@ int amdgpu_bo_create_restricted(struct amdgpu_device *adev,
 				       AMDGPU_GEM_DOMAIN_OA);
 
 	bo->flags = flags;
+
+	/* For architectures that don't support WC memory,
+	 * mask out the WC flag from the BO
+	 */
+	if (!drm_arch_can_wc_memory())
+		bo->flags &= ~AMDGPU_GEM_CREATE_CPU_GTT_USWC;
+
 	amdgpu_fill_placement_to_bo(bo, placement);
 	/* Kernel allocation are uninterruptible */
 	r = ttm_bo_init(&adev->mman.bdev, &bo->tbo, size, type,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 8a1752ff3d8e..55cf05e1c81c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -808,7 +808,7 @@ uint32_t amdgpu_ttm_tt_pte_flags(struct amdgpu_device *adev, struct ttm_tt *ttm,
 			flags |= AMDGPU_PTE_SNOOPED;
 	}
 
-	if (adev->asic_type >= CHIP_TOPAZ)
+	if (adev->asic_type >= CHIP_TONGA)
 		flags |= AMDGPU_PTE_EXECUTABLE;
 
 	flags |= AMDGPU_PTE_READABLE;
diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
index 72793f93e2fc..6c76139de1c9 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
@@ -4738,6 +4738,22 @@ static int gfx_v7_0_early_init(void *handle)
 	return 0;
 }
 
+static int gfx_v7_0_late_init(void *handle)
+{
+	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
+	int r;
+
+	r = amdgpu_irq_get(adev, &adev->gfx.priv_reg_irq, 0);
+	if (r)
+		return r;
+
+	r = amdgpu_irq_get(adev, &adev->gfx.priv_inst_irq, 0);
+	if (r)
+		return r;
+
+	return 0;
+}
+
 static int gfx_v7_0_sw_init(void *handle)
 {
 	struct amdgpu_ring *ring;
@@ -4890,6 +4906,8 @@ static int gfx_v7_0_hw_fini(void *handle)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
+	amdgpu_irq_put(adev, &adev->gfx.priv_reg_irq, 0);
+	amdgpu_irq_put(adev, &adev->gfx.priv_inst_irq, 0);
 	gfx_v7_0_cp_enable(adev, false);
 	gfx_v7_0_rlc_stop(adev);
 	gfx_v7_0_fini_pg(adev);
@@ -5527,7 +5545,7 @@ static int gfx_v7_0_set_powergating_state(void *handle,
 
 const struct amd_ip_funcs gfx_v7_0_ip_funcs = {
 	.early_init = gfx_v7_0_early_init,
-	.late_init = NULL,
+	.late_init = gfx_v7_0_late_init,
 	.sw_init = gfx_v7_0_sw_init,
 	.sw_fini = gfx_v7_0_sw_fini,
 	.hw_init = gfx_v7_0_hw_init,
diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
index 95c0cdfbd1b3..8f8ec37ecd88 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
@@ -111,7 +111,6 @@ MODULE_FIRMWARE("amdgpu/topaz_ce.bin");
 MODULE_FIRMWARE("amdgpu/topaz_pfp.bin");
 MODULE_FIRMWARE("amdgpu/topaz_me.bin");
 MODULE_FIRMWARE("amdgpu/topaz_mec.bin");
-MODULE_FIRMWARE("amdgpu/topaz_mec2.bin");
 MODULE_FIRMWARE("amdgpu/topaz_rlc.bin");
 
 MODULE_FIRMWARE("amdgpu/fiji_ce.bin");
@@ -828,7 +827,8 @@ static int gfx_v8_0_init_microcode(struct amdgpu_device *adev)
 	adev->gfx.mec_fw_version = le32_to_cpu(cp_hdr->header.ucode_version);
 	adev->gfx.mec_feature_version = le32_to_cpu(cp_hdr->ucode_feature_version);
 
-	if (adev->asic_type != CHIP_STONEY) {
+	if ((adev->asic_type != CHIP_STONEY) &&
+	    (adev->asic_type != CHIP_TOPAZ)) {
 		snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mec2.bin", chip_name);
 		err = request_firmware(&adev->gfx.mec2_fw, fw_name, adev->dev);
 		if (!err) {
@@ -3851,10 +3851,16 @@ static int gfx_v8_0_cp_resume(struct amdgpu_device *adev)
 			if (r)
 				return -EINVAL;
 
-			r = adev->smu.smumgr_funcs->check_fw_load_finish(adev,
-							AMDGPU_UCODE_ID_CP_MEC1);
-			if (r)
-				return -EINVAL;
+			if (adev->asic_type == CHIP_TOPAZ) {
+				r = gfx_v8_0_cp_compute_load_microcode(adev);
+				if (r)
+					return r;
+			} else {
+				r = adev->smu.smumgr_funcs->check_fw_load_finish(adev,
+										 AMDGPU_UCODE_ID_CP_MEC1);
+				if (r)
+					return -EINVAL;
+			}
 		}
 	}
 
@@ -3901,6 +3907,8 @@ static int gfx_v8_0_hw_fini(void *handle)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
+	amdgpu_irq_put(adev, &adev->gfx.priv_reg_irq, 0);
+	amdgpu_irq_put(adev, &adev->gfx.priv_inst_irq, 0);
 	gfx_v8_0_cp_enable(adev, false);
 	gfx_v8_0_rlc_stop(adev);
 	gfx_v8_0_cp_compute_fini(adev);
@@ -4329,6 +4337,14 @@ static int gfx_v8_0_late_init(void *handle)
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 	int r;
 
+	r = amdgpu_irq_get(adev, &adev->gfx.priv_reg_irq, 0);
+	if (r)
+		return r;
+
+	r = amdgpu_irq_get(adev, &adev->gfx.priv_inst_irq, 0);
+	if (r)
+		return r;
+
 	/* requires IBs so do in late init after IB pool is initialized */
 	r = gfx_v8_0_do_edc_gpr_workarounds(adev);
 	if (r)
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
index 3f956065d069..8aa2991ab379 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
@@ -42,9 +42,39 @@ static void gmc_v7_0_set_irq_funcs(struct amdgpu_device *adev);
 
 MODULE_FIRMWARE("radeon/bonaire_mc.bin");
 MODULE_FIRMWARE("radeon/hawaii_mc.bin");
+MODULE_FIRMWARE("amdgpu/topaz_mc.bin");
+
+static const u32 golden_settings_iceland_a11[] =
+{
+	mmVM_PRT_APERTURE0_LOW_ADDR, 0x0fffffff, 0x0fffffff,
+	mmVM_PRT_APERTURE1_LOW_ADDR, 0x0fffffff, 0x0fffffff,
+	mmVM_PRT_APERTURE2_LOW_ADDR, 0x0fffffff, 0x0fffffff,
+	mmVM_PRT_APERTURE3_LOW_ADDR, 0x0fffffff, 0x0fffffff
+};
+
+static const u32 iceland_mgcg_cgcg_init[] =
+{
+	mmMC_MEM_POWER_LS, 0xffffffff, 0x00000104
+};
+
+static void gmc_v7_0_init_golden_registers(struct amdgpu_device *adev)
+{
+	switch (adev->asic_type) {
+	case CHIP_TOPAZ:
+		amdgpu_program_register_sequence(adev,
+						 iceland_mgcg_cgcg_init,
+						 (const u32)ARRAY_SIZE(iceland_mgcg_cgcg_init));
+		amdgpu_program_register_sequence(adev,
+						 golden_settings_iceland_a11,
+						 (const u32)ARRAY_SIZE(golden_settings_iceland_a11));
+		break;
+	default:
+		break;
+	}
+}
 
 /**
- * gmc8_mc_wait_for_idle - wait for MC idle callback.
+ * gmc7_mc_wait_for_idle - wait for MC idle callback.
  *
  * @adev: amdgpu_device pointer
  *
@@ -132,13 +162,20 @@ static int gmc_v7_0_init_microcode(struct amdgpu_device *adev)
 	case CHIP_HAWAII:
 		chip_name = "hawaii";
 		break;
+	case CHIP_TOPAZ:
+		chip_name = "topaz";
+		break;
 	case CHIP_KAVERI:
 	case CHIP_KABINI:
 		return 0;
 	default: BUG();
 	}
 
-	snprintf(fw_name, sizeof(fw_name), "radeon/%s_mc.bin", chip_name);
+	if (adev->asic_type == CHIP_TOPAZ)
+		snprintf(fw_name, sizeof(fw_name), "amdgpu/%s_mc.bin", chip_name);
+	else
+		snprintf(fw_name, sizeof(fw_name), "radeon/%s_mc.bin", chip_name);
+
 	err = request_firmware(&adev->mc.fw, fw_name, adev->dev);
 	if (err)
 		goto out;
@@ -984,6 +1021,8 @@ static int gmc_v7_0_hw_init(void *handle)
 	int r;
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
+	gmc_v7_0_init_golden_registers(adev);
+
 	gmc_v7_0_mc_program(adev);
 
 	if (!(adev->flags & AMD_IS_APU)) {
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
index c0c9a0101eb4..3efd45546241 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
@@ -42,9 +42,7 @@
 static void gmc_v8_0_set_gart_funcs(struct amdgpu_device *adev);
 static void gmc_v8_0_set_irq_funcs(struct amdgpu_device *adev);
 
-MODULE_FIRMWARE("amdgpu/topaz_mc.bin");
 MODULE_FIRMWARE("amdgpu/tonga_mc.bin");
-MODULE_FIRMWARE("amdgpu/fiji_mc.bin");
 
 static const u32 golden_settings_tonga_a11[] =
 {
@@ -75,19 +73,6 @@ static const u32 fiji_mgcg_cgcg_init[] =
 	mmMC_MEM_POWER_LS, 0xffffffff, 0x00000104
 };
 
-static const u32 golden_settings_iceland_a11[] =
-{
-	mmVM_PRT_APERTURE0_LOW_ADDR, 0x0fffffff, 0x0fffffff,
-	mmVM_PRT_APERTURE1_LOW_ADDR, 0x0fffffff, 0x0fffffff,
-	mmVM_PRT_APERTURE2_LOW_ADDR, 0x0fffffff, 0x0fffffff,
-	mmVM_PRT_APERTURE3_LOW_ADDR, 0x0fffffff, 0x0fffffff
-};
-
-static const u32 iceland_mgcg_cgcg_init[] =
-{
-	mmMC_MEM_POWER_LS, 0xffffffff, 0x00000104
-};
-
 static const u32 cz_mgcg_cgcg_init[] =
 {
 	mmMC_MEM_POWER_LS, 0xffffffff, 0x00000104
@@ -102,14 +87,6 @@ static const u32 stoney_mgcg_cgcg_init[] =
 static void gmc_v8_0_init_golden_registers(struct amdgpu_device *adev)
 {
 	switch (adev->asic_type) {
-	case CHIP_TOPAZ:
-		amdgpu_program_register_sequence(adev,
-						 iceland_mgcg_cgcg_init,
-						 (const u32)ARRAY_SIZE(iceland_mgcg_cgcg_init));
-		amdgpu_program_register_sequence(adev,
-						 golden_settings_iceland_a11,
-						 (const u32)ARRAY_SIZE(golden_settings_iceland_a11));
-		break;
 	case CHIP_FIJI:
 		amdgpu_program_register_sequence(adev,
 						 fiji_mgcg_cgcg_init,
@@ -229,15 +206,10 @@ static int gmc_v8_0_init_microcode(struct amdgpu_device *adev)
 	DRM_DEBUG("\n");
 
 	switch (adev->asic_type) {
-	case CHIP_TOPAZ:
-		chip_name = "topaz";
-		break;
 	case CHIP_TONGA:
 		chip_name = "tonga";
 		break;
 	case CHIP_FIJI:
-		chip_name = "fiji";
-		break;
 	case CHIP_CARRIZO:
 	case CHIP_STONEY:
 		return 0;
@@ -1007,7 +979,7 @@ static int gmc_v8_0_hw_init(void *handle)
 
 	gmc_v8_0_mc_program(adev);
 
-	if (!(adev->flags & AMD_IS_APU)) {
+	if (adev->asic_type == CHIP_TONGA) {
 		r = gmc_v8_0_mc_load_microcode(adev);
 		if (r) {
 			DRM_ERROR("Failed to load MC firmware!\n");
diff --git a/drivers/gpu/drm/amd/amdgpu/iceland_smc.c b/drivers/gpu/drm/amd/amdgpu/iceland_smc.c
index 966d4b2ed9da..090486c18249 100644
--- a/drivers/gpu/drm/amd/amdgpu/iceland_smc.c
+++ b/drivers/gpu/drm/amd/amdgpu/iceland_smc.c
@@ -432,7 +432,7 @@ static uint32_t iceland_smu_get_mask_for_fw_type(uint32_t fw_type)
 		case AMDGPU_UCODE_ID_CP_ME:
 			return UCODE_ID_CP_ME_MASK;
 		case AMDGPU_UCODE_ID_CP_MEC1:
-			return UCODE_ID_CP_MEC_MASK | UCODE_ID_CP_MEC_JT1_MASK | UCODE_ID_CP_MEC_JT2_MASK;
+			return UCODE_ID_CP_MEC_MASK | UCODE_ID_CP_MEC_JT1_MASK;
 		case AMDGPU_UCODE_ID_CP_MEC2:
 			return UCODE_ID_CP_MEC_MASK;
 		case AMDGPU_UCODE_ID_RLC_G:
@@ -522,12 +522,6 @@ static int iceland_smu_request_load_fw(struct amdgpu_device *adev)
 		return -EINVAL;
 	}
 
-	if (iceland_smu_populate_single_firmware_entry(adev, UCODE_ID_CP_MEC_JT2,
-			&toc->entry[toc->num_entries++])) {
-		DRM_ERROR("Failed to get firmware entry for MEC_JT2\n");
-		return -EINVAL;
-	}
-
 	if (iceland_smu_populate_single_firmware_entry(adev, UCODE_ID_SDMA0,
 			&toc->entry[toc->num_entries++])) {
 		DRM_ERROR("Failed to get firmware entry for SDMA0\n");
@@ -550,8 +544,8 @@ static int iceland_smu_request_load_fw(struct amdgpu_device *adev)
 			UCODE_ID_CP_ME_MASK |
 			UCODE_ID_CP_PFP_MASK |
 			UCODE_ID_CP_MEC_MASK |
-			UCODE_ID_CP_MEC_JT1_MASK |
-			UCODE_ID_CP_MEC_JT2_MASK;
+			UCODE_ID_CP_MEC_JT1_MASK;
+
 
 	if (iceland_send_msg_to_smc_with_parameter_without_waiting(adev, PPSMC_MSG_LoadUcodes, fw_to_load)) {
 		DRM_ERROR("Fail to request SMU load ucode\n");
diff --git a/drivers/gpu/drm/amd/amdgpu/vi.c b/drivers/gpu/drm/amd/amdgpu/vi.c
index 652e76644c31..89f5a1ff6f43 100644
--- a/drivers/gpu/drm/amd/amdgpu/vi.c
+++ b/drivers/gpu/drm/amd/amdgpu/vi.c
@@ -61,6 +61,7 @@
 #include "vi.h"
 #include "vi_dpm.h"
 #include "gmc_v8_0.h"
+#include "gmc_v7_0.h"
 #include "gfx_v8_0.h"
 #include "sdma_v2_4.h"
 #include "sdma_v3_0.h"
@@ -1109,10 +1110,10 @@ static const struct amdgpu_ip_block_version topaz_ip_blocks[] =
 	},
 	{
 		.type = AMD_IP_BLOCK_TYPE_GMC,
-		.major = 8,
-		.minor = 0,
+		.major = 7,
+		.minor = 4,
 		.rev = 0,
-		.funcs = &gmc_v8_0_ip_funcs,
+		.funcs = &gmc_v7_0_ip_funcs,
 	},
 	{
 		.type = AMD_IP_BLOCK_TYPE_IH,
@@ -1442,8 +1443,7 @@ static int vi_common_early_init(void *handle)
 		break;
 	case CHIP_FIJI:
 		adev->has_uvd = true;
-		adev->cg_flags = AMDGPU_CG_SUPPORT_UVD_MGCG |
-				AMDGPU_CG_SUPPORT_VCE_MGCG;
+		adev->cg_flags = 0;
 		adev->pg_flags = 0;
 		adev->external_rev_id = adev->rev_id + 0x3c;
 		break;
diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
index 84d45633d28c..fb6ad143873f 100644
--- a/drivers/gpu/drm/radeon/radeon_object.c
+++ b/drivers/gpu/drm/radeon/radeon_object.c
@@ -33,6 +33,7 @@
 #include <linux/slab.h>
 #include <drm/drmP.h>
 #include <drm/radeon_drm.h>
+#include <drm/drm_cache.h>
 #include "radeon.h"
 #include "radeon_trace.h"
 
@@ -245,6 +246,12 @@ int radeon_bo_create(struct radeon_device *rdev,
 		DRM_INFO_ONCE("Please enable CONFIG_MTRR and CONFIG_X86_PAT for "
 			      "better performance thanks to write-combining\n");
 	bo->flags &= ~(RADEON_GEM_GTT_WC | RADEON_GEM_GTT_UC);
+#else
+	/* For architectures that don't support WC memory,
+	 * mask out the WC flag from the BO
+	 */
+	if (!drm_arch_can_wc_memory())
+		bo->flags &= ~RADEON_GEM_GTT_WC;
 #endif
 
 	radeon_ttm_placement_from_domain(bo, domain);