linux-kernel - [PATCH v5 6/7] drm/vkms: Add a module param to enable/disable the default device

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Message-ID: <20230828081929.3574228-7-brpol@chromium.org>
Date:   Mon, 28 Aug 2023 08:17:08 +0000
From:   Brandon Pollack <brpol@...omium.org>
To:     marius.vlad@...labora.com, mairacanal@...eup.net,
        jshargo@...omium.org
Cc:     corbet@....net, dri-devel@...ts.freedesktop.org,
        hamohammed.sa@...il.com, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, melissa.srw@...il.com,
        mripard@...nel.org, rodrigosiqueiramelo@...il.com,
        tzimmermann@...e.de, airlied@...il.com, daniel@...ll.ch,
        maarten.lankhorst@...ux.intel.com, mduggan@...omium.org,
        hirono@...omium.org, Brandon Pollack <brpol@...omium.org>
Subject: [PATCH v5 6/7] drm/vkms: Add a module param to enable/disable the default device

From: Jim Shargo <jshargo@...omium.org>

In many testing circumstances, we will want to just create a new device
and test against that. If we create a default device, it can be annoying
to have to manually select the new device instead of choosing the only
one that exists.

The param, enable_default, is defaulted to true to maintain backwards
compatibility.

Signed-off-by: Jim Shargo <jshargo@...omium.org>
Signed-off-by: Brandon Pollack <brpol@...omium.org>
---
 drivers/gpu/drm/vkms/vkms_drv.c | 45 ++++++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index 6e7f20681890..293bebf8e8ce 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -42,17 +42,26 @@
 #define DRIVER_MAJOR	1
 #define DRIVER_MINOR	0
 
+static bool enable_default_device = true;
+module_param_named(enable_default_device, enable_default_device, bool, 0444);
+MODULE_PARM_DESC(enable_default_device,
+		 "Enable/Disable creating the default device");
+
 static bool enable_cursor = true;
 module_param_named(enable_cursor, enable_cursor, bool, 0444);
-MODULE_PARM_DESC(enable_cursor, "Enable/Disable cursor support");
+MODULE_PARM_DESC(enable_cursor,
+		 "Enable/Disable cursor support for the default device");
 
 static bool enable_writeback = true;
 module_param_named(enable_writeback, enable_writeback, bool, 0444);
-MODULE_PARM_DESC(enable_writeback, "Enable/Disable writeback connector support");
+MODULE_PARM_DESC(
+	enable_writeback,
+	"Enable/Disable writeback connector support for the default device");
 
 static bool enable_overlay;
 module_param_named(enable_overlay, enable_overlay, bool, 0444);
-MODULE_PARM_DESC(enable_overlay, "Enable/Disable overlay support");
+MODULE_PARM_DESC(enable_overlay,
+		 "Enable/Disable overlay support for the default device");
 
 DEFINE_DRM_GEM_FOPS(vkms_driver_fops);
 
@@ -99,6 +108,7 @@ static int vkms_config_show(struct seq_file *m, void *data)
 	struct drm_device *dev = entry->dev;
 	struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev);
 
+	seq_printf(m, "default_device=%d\n", enable_default_device);
 	seq_printf(m, "writeback=%d\n", vkmsdev->config.writeback);
 	seq_printf(m, "cursor=%d\n", vkmsdev->config.cursor);
 	seq_printf(m, "overlay=%d\n", vkmsdev->config.overlay);
@@ -297,10 +307,7 @@ void vkms_remove_device(struct vkms_device *vkms_device)
 static int __init vkms_init(void)
 {
 	int ret;
-	struct platform_device *pdev;
-	struct vkms_device_setup vkms_device_setup = {
-		.configfs = NULL,
-	};
+	struct platform_device *default_pdev = NULL;
 
 	ret = platform_driver_register(&vkms_platform_driver);
 	if (ret) {
@@ -308,19 +315,27 @@ static int __init vkms_init(void)
 		return ret;
 	}
 
-	pdev = platform_device_register_data(NULL, DRIVER_NAME, 0,
-					     &vkms_device_setup,
-					     sizeof(vkms_device_setup));
-	if (IS_ERR(pdev)) {
-		DRM_ERROR("Unable to register default vkms device\n");
-		platform_driver_unregister(&vkms_platform_driver);
-		return PTR_ERR(pdev);
+	if (enable_default_device) {
+		struct vkms_device_setup vkms_device_setup = {
+			.configfs = NULL,
+		};
+
+		default_pdev = platform_device_register_data(
+			NULL, DRIVER_NAME, 0, &vkms_device_setup,
+			sizeof(vkms_device_setup));
+		if (IS_ERR(default_pdev)) {
+			DRM_ERROR("Unable to register default vkms device\n");
+			platform_driver_unregister(&vkms_platform_driver);
+			return PTR_ERR(default_pdev);
+		}
 	}
 
 	ret = vkms_init_configfs();
 	if (ret) {
 		DRM_ERROR("Unable to initialize configfs\n");
-		platform_device_unregister(pdev);
+		if (default_pdev)
+			platform_device_unregister(default_pdev);
+
 		platform_driver_unregister(&vkms_platform_driver);
 	}
 
-- 
2.42.0.rc1.204.g551eb34607-goog