drm/amdgpu: Create helper to clear AMDGPU_GEM_CREATE_CPU_GTT_USWC

Move the logic to clear AMDGPU_GEM_CREATE_CPU_GTT_USWC in
amdgpu_bo_do_create into standalone helper so it can be reused
in other functions.

v4:
Switch to return bool.

v5: Fix typos.
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Acked-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_object.c

@@ -413,6 +413,40 @@ static bool amdgpu_bo_validate_size(struct amdgpu_device *adev,
 	return false;
 }
 
+bool amdgpu_bo_support_uswc(u64 bo_flags)
+{
+
+#ifdef CONFIG_X86_32
+	/* XXX: Write-combined CPU mappings of GTT seem broken on 32-bit
+	 * See https://bugs.freedesktop.org/show_bug.cgi?id=84627
+	 */
+	return false;
+#elif defined(CONFIG_X86) && !defined(CONFIG_X86_PAT)
+	/* Don't try to enable write-combining when it can't work, or things
+	 * may be slow
+	 * See https://bugs.freedesktop.org/show_bug.cgi?id=88758
+	 */
+
+#ifndef CONFIG_COMPILE_TEST
+#warning Please enable CONFIG_MTRR and CONFIG_X86_PAT for better performance \
+	 thanks to write-combining
+#endif
+
+	if (bo_flags & AMDGPU_GEM_CREATE_CPU_GTT_USWC)
+		DRM_INFO_ONCE("Please enable CONFIG_MTRR and CONFIG_X86_PAT for "
+			      "better performance thanks to write-combining\n");
+	return false;
+#else
+	/* For architectures that don't support WC memory,
+	 * mask out the WC flag from the BO
+	 */
+	if (!drm_arch_can_wc_memory())
+		return false;
+
+	return true;
+#endif
+}
+
 static int amdgpu_bo_do_create(struct amdgpu_device *adev,
 			       struct amdgpu_bo_param *bp,
 			       struct amdgpu_bo **bo_ptr)
@@ -466,33 +500,8 @@ static int amdgpu_bo_do_create(struct amdgpu_device *adev,
 
 	bo->flags = bp->flags;
 
-#ifdef CONFIG_X86_32
-	/* XXX: Write-combined CPU mappings of GTT seem broken on 32-bit
-	 * See https://bugs.freedesktop.org/show_bug.cgi?id=84627
-	 */
-	bo->flags &= ~AMDGPU_GEM_CREATE_CPU_GTT_USWC;
-#elif defined(CONFIG_X86) && !defined(CONFIG_X86_PAT)
-	/* Don't try to enable write-combining when it can't work, or things
-	 * may be slow
-	 * See https://bugs.freedesktop.org/show_bug.cgi?id=88758
-	 */
-
-#ifndef CONFIG_COMPILE_TEST
-#warning Please enable CONFIG_MTRR and CONFIG_X86_PAT for better performance \
-	 thanks to write-combining
-#endif
-
-	if (bo->flags & AMDGPU_GEM_CREATE_CPU_GTT_USWC)
-		DRM_INFO_ONCE("Please enable CONFIG_MTRR and CONFIG_X86_PAT for "
-			      "better performance thanks to write-combining\n");
-	bo->flags &= ~AMDGPU_GEM_CREATE_CPU_GTT_USWC;
-#else
-	/* For architectures that don't support WC memory,
-	 * mask out the WC flag from the BO
-	 */
-	if (!drm_arch_can_wc_memory())
+	if (!amdgpu_bo_support_uswc(bo->flags))
 		bo->flags &= ~AMDGPU_GEM_CREATE_CPU_GTT_USWC;
-#endif
 
 	bo->tbo.bdev = &adev->mman.bdev;
 	if (bp->domain & (AMDGPU_GEM_DOMAIN_GWS | AMDGPU_GEM_DOMAIN_OA |

drivers/gpu/drm/amd/amdgpu/amdgpu_object.h

@@ -308,5 +308,7 @@ void amdgpu_sa_bo_dump_debug_info(struct amdgpu_sa_manager *sa_manager,
 					 struct seq_file *m);
 #endif
 
+bool amdgpu_bo_support_uswc(u64 bo_flags);
+
 
 #endif