drm/amdgpu: add DC feature mask module parameter

Similar to ppfeaturemask.  Allows you to selectively enable/disable
DC features.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -152,6 +152,7 @@ extern int amdgpu_compute_multipipe;
 extern int amdgpu_gpu_recovery;
 extern int amdgpu_emu_mode;
 extern uint amdgpu_smu_memory_pool_size;
+extern uint amdgpu_dc_feature_mask;
 extern struct amdgpu_mgpu_info mgpu_info;
 
 #ifdef CONFIG_DRM_AMDGPU_SI

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

@@ -127,6 +127,9 @@ int amdgpu_compute_multipipe = -1;
 int amdgpu_gpu_recovery = -1; /* auto */
 int amdgpu_emu_mode = 0;
 uint amdgpu_smu_memory_pool_size = 0;
+/* FBC (bit 0) disabled by default*/
+uint amdgpu_dc_feature_mask = 0;
+
 struct amdgpu_mgpu_info mgpu_info = {
 	.mutex = __MUTEX_INITIALIZER(mgpu_info.mutex),
 };
@@ -631,6 +634,14 @@ module_param(halt_if_hws_hang, int, 0644);
 MODULE_PARM_DESC(halt_if_hws_hang, "Halt if HWS hang is detected (0 = off (default), 1 = on)");
 #endif
 
+/**
+ * DOC: dcfeaturemask (uint)
+ * Override display features enabled. See enum DC_FEATURE_MASK in drivers/gpu/drm/amd/include/amd_shared.h.
+ * The default is the current set of stable display features.
+ */
+MODULE_PARM_DESC(dcfeaturemask, "all stable DC features enabled (default))");
+module_param_named(dcfeaturemask, amdgpu_dc_feature_mask, uint, 0444);
+
 static const struct pci_device_id pciidlist[] = {
 #ifdef  CONFIG_DRM_AMDGPU_SI
 	{0x1002, 0x6780, PCI_ANY_ID, PCI_ANY_ID, 0, 0, CHIP_TAHITI},

drivers/gpu/drm/amd/include/amd_shared.h

@@ -133,6 +133,10 @@ enum PP_FEATURE_MASK {
 	PP_AVFS_MASK = 0x40000,
 };
 
+enum DC_FEATURE_MASK {
+	DC_FBC_MASK = 0x1,
+};
+
 /**
  * struct amd_ip_funcs - general hooks for managing amdgpu IP Blocks
  */