drm/amdgpu: Use amdgpu by default on CIK dedicated GPUs

The amdgpu driver has been working well on CIK dGPUs for years.
Now that the DC analog connector support landed, these GPUs
are at feature parity with the old radeon driver.

Additionally, amdgpu yields extra performance, supports Vulkan
and provides more display features through DC as well as more
robust power management.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Timur Kristóf

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

@@ -641,7 +641,9 @@ module_param_named(si_support, amdgpu_si_support, int, 0444);
  * CIK (Sea Islands) are second generation GCN GPUs, supported by both
  * drivers: radeon (old) and amdgpu (new). This parameter controls whether
  * amdgpu should support CIK.
- * By default, CIK chips are supported by radeon (except when radeon is not built).
+ * By default:
+ * - CIK dedicated GPUs are supported by amdgpu.
+ * - CIK APUs are supported by radeon (except when radeon is not built).
  * Only relevant when CONFIG_DRM_AMDGPU_CIK is enabled to build CIK support in amdgpu.
  * See also radeon.cik_support which should be disabled when amdgpu.cik_support is
  * enabled, and vice versa.
@@ -2328,6 +2330,8 @@ static bool amdgpu_support_enabled(struct device *dev,
 
 	case CHIP_BONAIRE:
 	case CHIP_HAWAII:
+		support_by_default = true;
+		fallthrough;
 	case CHIP_KAVERI:
 	case CHIP_KABINI:
 	case CHIP_MULLINS:

drivers/gpu/drm/radeon/radeon_drv.c

@@ -277,6 +277,8 @@ static bool radeon_support_enabled(struct device *dev,
 
 	case CHIP_BONAIRE:
 	case CHIP_HAWAII:
+		support_by_default = false;
+		fallthrough;
 	case CHIP_KAVERI:
 	case CHIP_KABINI:
 	case CHIP_MULLINS: