drm/amd: Add a module parameter for seamless boot

The module parameter can be used to test more easily enabling seamless
boot support on additional ASICs.
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -245,6 +245,7 @@ extern int amdgpu_num_kcq;
 extern int amdgpu_vcnfw_log;
 extern int amdgpu_sg_display;
 extern int amdgpu_umsch_mm;
+extern int amdgpu_seamless;
 
 extern int amdgpu_user_partt_mode;
 

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

@@ -1367,11 +1367,25 @@ bool amdgpu_device_need_post(struct amdgpu_device *adev)
  */
 bool amdgpu_device_seamless_boot_supported(struct amdgpu_device *adev)
 {
+	switch (amdgpu_seamless) {
+	case -1:
+		break;
+	case 1:
+		return true;
+	case 0:
+		return false;
+	default:
+		DRM_ERROR("Invalid value for amdgpu.seamless: %d\n",
+			  amdgpu_seamless);
+		return false;
+	}
+
+	if (adev->mman.keep_stolen_vga_memory)
+		return false;
+
 	switch (adev->ip_versions[DCE_HWIP][0]) {
 	case IP_VERSION(3, 0, 1):
-		if (!adev->mman.keep_stolen_vga_memory)
-			return true;
-		break;
+		return true;
 	default:
 		break;
 	}

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

@@ -203,6 +203,7 @@ int amdgpu_vcnfw_log;
 int amdgpu_sg_display = -1; /* auto */
 int amdgpu_user_partt_mode = AMDGPU_AUTO_COMPUTE_PARTITION_MODE;
 int amdgpu_umsch_mm;
+int amdgpu_seamless = -1; /* auto */
 uint amdgpu_debug_mask;
 
 static void amdgpu_drv_delayed_reset_work_handler(struct work_struct *work);
@@ -938,6 +939,13 @@ module_param_named(user_partt_mode, amdgpu_user_partt_mode, uint, 0444);
 module_param(enforce_isolation, bool, 0444);
 MODULE_PARM_DESC(enforce_isolation, "enforce process isolation between graphics and compute . enforce_isolation = on");
 
+/**
+ * DOC: seamless (int)
+ * Seamless boot will keep the image on the screen during the boot process.
+ */
+MODULE_PARM_DESC(seamless, "Seamless boot (-1 = auto (default), 0 = disable, 1 = enable)");
+module_param_named(seamless, amdgpu_seamless, int, 0444);
+
 /**
  * DOC: debug_mask (uint)
  * Debug options for amdgpu, work as a binary mask with the following options: