drm/amdgpu: Use amdgpu by default for CIK APUs too

CIK APUs are: Kaveri, Kabini and Mullins from 2013~2015,
which all have a second generation GCN based integrated GPU.

The amdgpu driver has been working well on CIK APUs for years.
Features which were previously missing have been added recently,
specifically DC support for analog connectors and DP bridge
encoders. Now amdgpu is at feature parity with the old radeon
driver on CIK APUs.

Enabling the amdgpu driver by default for CIK APUs has the
following benefits:

- More stable OpenGL support through RadeonSI
- Vulkan support through RADV
- Improved performance
- Better display features through DC

Users who want to keep using the old driver can do so using:
amdgpu.cik_support=0 radeon.cik_support=1

Signed-off-by: Timur Kristóf <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Timur Kristóf

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

@@ -641,9 +641,7 @@ 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 dedicated GPUs are supported by amdgpu.
- * - CIK APUs are supported by radeon (except when radeon is not built).
+ * By default, CIK dedicated GPUs and APUs are supported by amdgpu.
  * 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.
@@ -2323,15 +2321,14 @@ 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:
 		gen = "CIK";
 		param = "cik_support";
 		module_param = amdgpu_cik_support;
 		amdgpu_support_built = IS_ENABLED(CONFIG_DRM_AMDGPU_CIK);
+		support_by_default = true;
 		break;
 
 	default:

drivers/gpu/drm/radeon/radeon_drv.c

@@ -278,14 +278,13 @@ 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:
 		gen = "CIK";
 		module_param = radeon_cik_support;
 		amdgpu_support_built &= IS_ENABLED(CONFIG_DRM_AMDGPU_CIK);
+		support_by_default = false;
 		break;
 
 	default: