Creating a new vkms_config structure will be more complex once we
start adding more options.

Extract the vkms_config structure to its own header and source files
and add functions to create and delete a vkms_config and to initialize
debugfs.

Refactor, no functional changes.

Co-developed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
---
 drivers/gpu/drm/vkms/Makefile                 |  3 +-
 drivers/gpu/drm/vkms/tests/vkms_config_test.c | 13 +++++
 drivers/gpu/drm/vkms/vkms_config.c            | 47 +++++++++++++++++++
 drivers/gpu/drm/vkms/vkms_config.h            | 47 +++++++++++++++++++
 drivers/gpu/drm/vkms/vkms_drv.c               | 34 +++-----------
 drivers/gpu/drm/vkms/vkms_drv.h               | 15 +-----
 drivers/gpu/drm/vkms/vkms_output.c            |  1 +
 7 files changed, 118 insertions(+), 42 deletions(-)
 create mode 100644 drivers/gpu/drm/vkms/vkms_config.c
 create mode 100644 drivers/gpu/drm/vkms/vkms_config.h

diff --git a/drivers/gpu/drm/vkms/Makefile b/drivers/gpu/drm/vkms/Makefile
index 45ef4b89379e..9bf6b8f94daf 100644
--- a/drivers/gpu/drm/vkms/Makefile
+++ b/drivers/gpu/drm/vkms/Makefile
@@ -7,7 +7,8 @@ vkms-y := \
 	vkms_crtc.o \
 	vkms_composer.o \
 	vkms_writeback.o \
-	vkms_connector.o
+	vkms_connector.o \
+	vkms_config.o
 
 obj-$(CONFIG_DRM_VKMS) += vkms.o
 obj-$(CONFIG_DRM_VKMS_KUNIT_TESTS) += tests/
diff --git a/drivers/gpu/drm/vkms/tests/vkms_config_test.c b/drivers/gpu/drm/vkms/tests/vkms_config_test.c
index 1177e62e19cb..a7060504f3dc 100644
--- a/drivers/gpu/drm/vkms/tests/vkms_config_test.c
+++ b/drivers/gpu/drm/vkms/tests/vkms_config_test.c
@@ -2,9 +2,22 @@
 
 #include <kunit/test.h>
 
+#include "../vkms_config.h"
+
 MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");
 
+static void vkms_config_test_empty_config(struct kunit *test)
+{
+	struct vkms_config *config;
+
+	config = vkms_config_create();
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, config);
+
+	vkms_config_destroy(config);
+}
+
 static struct kunit_case vkms_config_test_cases[] = {
+	KUNIT_CASE(vkms_config_test_empty_config),
 	{}
 };
 
diff --git a/drivers/gpu/drm/vkms/vkms_config.c b/drivers/gpu/drm/vkms/vkms_config.c
new file mode 100644
index 000000000000..152b2ecd6aef
--- /dev/null
+++ b/drivers/gpu/drm/vkms/vkms_config.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/slab.h>
+
+#include <drm/drm_print.h>
+#include <drm/drm_debugfs.h>
+
+#include "vkms_config.h"
+
+struct vkms_config *vkms_config_create(void)
+{
+	struct vkms_config *config;
+
+	config = kzalloc(sizeof(*config), GFP_KERNEL);
+	if (!config)
+		return ERR_PTR(-ENOMEM);
+
+	return config;
+}
+
+void vkms_config_destroy(struct vkms_config *config)
+{
+	kfree(config);
+}
+
+static int vkms_config_show(struct seq_file *m, void *data)
+{
+	struct drm_debugfs_entry *entry = m->private;
+	struct drm_device *dev = entry->dev;
+	struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev);
+
+	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);
+
+	return 0;
+}
+
+static const struct drm_debugfs_info vkms_config_debugfs_list[] = {
+	{ "vkms_config", vkms_config_show, 0 },
+};
+
+void vkms_config_register_debugfs(struct vkms_device *vkms_device)
+{
+	drm_debugfs_add_files(&vkms_device->drm, vkms_config_debugfs_list,
+			      ARRAY_SIZE(vkms_config_debugfs_list));
+}
diff --git a/drivers/gpu/drm/vkms/vkms_config.h b/drivers/gpu/drm/vkms/vkms_config.h
new file mode 100644
index 000000000000..ced10f56a812
--- /dev/null
+++ b/drivers/gpu/drm/vkms/vkms_config.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef _VKMS_CONFIG_H_
+#define _VKMS_CONFIG_H_
+
+#include <linux/types.h>
+
+#include "vkms_drv.h"
+
+/**
+ * struct vkms_config - General configuration for VKMS driver
+ *
+ * @writeback: If true, a writeback buffer can be attached to the CRTC
+ * @cursor: If true, a cursor plane is created in the VKMS device
+ * @overlay: If true, NUM_OVERLAY_PLANES will be created for the VKMS device
+ * @dev: Used to store the current VKMS device. Only set when the device is instantiated.
+ */
+struct vkms_config {
+	bool writeback;
+	bool cursor;
+	bool overlay;
+	struct vkms_device *dev;
+};
+
+/**
+ * vkms_config_create() - Create a new VKMS configuration
+ *
+ * Returns:
+ * The new vkms_config or an error. Call vkms_config_destroy() to free the
+ * returned configuration.
+ */
+struct vkms_config *vkms_config_create(void);
+
+/**
+ * vkms_config_destroy() - Free a VKMS configuration
+ * @config: vkms_config to free
+ */
+void vkms_config_destroy(struct vkms_config *config);
+
+/**
+ * vkms_config_register_debugfs() - Register a debugfs file to show the device's
+ * configuration
+ * @vkms_device: Device to register
+ */
+void vkms_config_register_debugfs(struct vkms_device *vkms_device);
+
+#endif /* _VKMS_CONFIG_H_ */
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index b6de91134a22..37de0658e6ee 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -27,11 +27,9 @@
 #include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_vblank.h>
 
+#include "vkms_config.h"
 #include "vkms_drv.h"
 
-#include <drm/drm_print.h>
-#include <drm/drm_debugfs.h>
-
 #define DRIVER_NAME	"vkms"
 #define DRIVER_DESC	"Virtual Kernel Mode Setting"
 #define DRIVER_MAJOR	1
@@ -81,23 +79,6 @@ static void vkms_atomic_commit_tail(struct drm_atomic_state *old_state)
 	drm_atomic_helper_cleanup_planes(dev, old_state);
 }
 
-static int vkms_config_show(struct seq_file *m, void *data)
-{
-	struct drm_debugfs_entry *entry = m->private;
-	struct drm_device *dev = entry->dev;
-	struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev);
-
-	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);
-
-	return 0;
-}
-
-static const struct drm_debugfs_info vkms_config_debugfs_list[] = {
-	{ "vkms_config", vkms_config_show, 0 },
-};
-
 static const struct drm_driver vkms_driver = {
 	.driver_features	= DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_GEM,
 	.fops			= &vkms_driver_fops,
@@ -208,8 +189,7 @@ static int vkms_create(struct vkms_config *config)
 	if (ret)
 		goto out_devres;
 
-	drm_debugfs_add_files(&vkms_device->drm, vkms_config_debugfs_list,
-			      ARRAY_SIZE(vkms_config_debugfs_list));
+	vkms_config_register_debugfs(vkms_device);
 
 	ret = drm_dev_register(&vkms_device->drm, 0);
 	if (ret)
@@ -231,9 +211,9 @@ static int __init vkms_init(void)
 	int ret;
 	struct vkms_config *config;
 
-	config = kmalloc(sizeof(*config), GFP_KERNEL);
-	if (!config)
-		return -ENOMEM;
+	config = vkms_config_create();
+	if (IS_ERR(config))
+		return PTR_ERR(config);
 
 	config->cursor = enable_cursor;
 	config->writeback = enable_writeback;
@@ -241,7 +221,7 @@ static int __init vkms_init(void)
 
 	ret = vkms_create(config);
 	if (ret) {
-		kfree(config);
+		vkms_config_destroy(config);
 		return ret;
 	}
 
@@ -275,7 +255,7 @@ static void __exit vkms_exit(void)
 		return;
 
 	vkms_destroy(default_config);
-	kfree(default_config);
+	vkms_config_destroy(default_config);
 }
 
 module_init(vkms_init);
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index abbb652be2b5..af7081c940d6 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -189,20 +189,7 @@ struct vkms_output {
 	spinlock_t composer_lock;
 };
 
-/**
- * struct vkms_config - General configuration for VKMS driver
- *
- * @writeback: If true, a writeback buffer can be attached to the CRTC
- * @cursor: If true, a cursor plane is created in the VKMS device
- * @overlay: If true, NUM_OVERLAY_PLANES will be created for the VKMS device
- * @dev: Used to store the current VKMS device. Only set when the device is instantiated.
- */
-struct vkms_config {
-	bool writeback;
-	bool cursor;
-	bool overlay;
-	struct vkms_device *dev;
-};
+struct vkms_config;
 
 /**
  * struct vkms_device - Description of a VKMS device
diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
index 4b5abe159add..068a7f87ecec 100644
--- a/drivers/gpu/drm/vkms/vkms_output.c
+++ b/drivers/gpu/drm/vkms/vkms_output.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0+
 
+#include "vkms_config.h"
 #include "vkms_connector.h"
 #include "vkms_drv.h"
 #include <drm/drm_managed.h>
-- 
2.48.1

On 11/02/25 - 12:09, José Expósito wrote:
> Creating a new vkms_config structure will be more complex once we
> start adding more options.
> 
> Extract the vkms_config structure to its own header and source files
> and add functions to create and delete a vkms_config and to initialize
> debugfs.
> 
> Refactor, no functional changes.
> 
> Co-developed-by: Louis Chauvet <louis.chauvet@bootlin.com>
> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> Signed-off-by: José Expósito <jose.exposito89@gmail.com>

This does not build in module, can you add this in the next version?

diff --git a/drivers/gpu/drm/vkms/vkms_config.c b/drivers/gpu/drm/vkms/vkms_config.c
index 152b2ecd6aef..42caa421876e 100644
--- a/drivers/gpu/drm/vkms/vkms_config.c
+++ b/drivers/gpu/drm/vkms/vkms_config.c
@@ -4,6 +4,7 @@

 #include <drm/drm_print.h>
 #include <drm/drm_debugfs.h>
+#include <kunit/visibility.h>

 #include "vkms_config.h"

@@ -17,11 +18,13 @@ struct vkms_config *vkms_config_create(void)

        return config;
 }
+EXPORT_SYMBOL_IF_KUNIT(vkms_config_create);

 void vkms_config_destroy(struct vkms_config *config)
 {
        kfree(config);
 }
+EXPORT_SYMBOL_IF_KUNIT(vkms_config_destroy);

 static int vkms_config_show(struct seq_file *m, void *data)
 {

With this:

Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>

On Thu, Feb 13, 2025 at 02:59:25PM +0100, Louis Chauvet wrote:
> On 11/02/25 - 12:09, José Expósito wrote:
> > Creating a new vkms_config structure will be more complex once we
> > start adding more options.
> > 
> > Extract the vkms_config structure to its own header and source files
> > and add functions to create and delete a vkms_config and to initialize
> > debugfs.
> > 
> > Refactor, no functional changes.
> > 
> > Co-developed-by: Louis Chauvet <louis.chauvet@bootlin.com>
> > Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> > Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> 
> This does not build in module, can you add this in the next version?

Interesting. I have "CONFIG_DRM_VKMS=m" in my config and it compiles here.

What do you have as module? CONFIG_DRM_VKMS_KUNIT_TESTS=m?

I'll rebuild every patch to make sure there are no errors.

Thanks for the heads up!
Jose
 
> diff --git a/drivers/gpu/drm/vkms/vkms_config.c b/drivers/gpu/drm/vkms/vkms_config.c
> index 152b2ecd6aef..42caa421876e 100644
> --- a/drivers/gpu/drm/vkms/vkms_config.c
> +++ b/drivers/gpu/drm/vkms/vkms_config.c
> @@ -4,6 +4,7 @@
> 
>  #include <drm/drm_print.h>
>  #include <drm/drm_debugfs.h>
> +#include <kunit/visibility.h>
> 
>  #include "vkms_config.h"
> 
> @@ -17,11 +18,13 @@ struct vkms_config *vkms_config_create(void)
> 
>         return config;
>  }
> +EXPORT_SYMBOL_IF_KUNIT(vkms_config_create);
> 
>  void vkms_config_destroy(struct vkms_config *config)
>  {
>         kfree(config);
>  }
> +EXPORT_SYMBOL_IF_KUNIT(vkms_config_destroy);
> 
>  static int vkms_config_show(struct seq_file *m, void *data)
>  {
> 
> With this:
> 
> Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>

Le 13/02/2025 à 16:36, José Expósito a écrit :
> On Thu, Feb 13, 2025 at 02:59:25PM +0100, Louis Chauvet wrote:
>> On 11/02/25 - 12:09, José Expósito wrote:
>>> Creating a new vkms_config structure will be more complex once we
>>> start adding more options.
>>>
>>> Extract the vkms_config structure to its own header and source files
>>> and add functions to create and delete a vkms_config and to initialize
>>> debugfs.
>>>
>>> Refactor, no functional changes.
>>>
>>> Co-developed-by: Louis Chauvet <louis.chauvet@bootlin.com>
>>> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
>>> Signed-off-by: José Expósito <jose.exposito89@gmail.com>
>>
>> This does not build in module, can you add this in the next version?
> 
> Interesting. I have "CONFIG_DRM_VKMS=m" in my config and it compiles here.
> 
> What do you have as module? CONFIG_DRM_VKMS_KUNIT_TESTS=m?

Yes sorry, I forgot to say it was for kunit tests. I just saw your other 
mail, thank you for the fix on all patches!

Louis Chauvet

> I'll rebuild every patch to make sure there are no errors.
> 
> Thanks for the heads up!
> Jose
>   
>> diff --git a/drivers/gpu/drm/vkms/vkms_config.c b/drivers/gpu/drm/vkms/vkms_config.c
>> index 152b2ecd6aef..42caa421876e 100644
>> --- a/drivers/gpu/drm/vkms/vkms_config.c
>> +++ b/drivers/gpu/drm/vkms/vkms_config.c
>> @@ -4,6 +4,7 @@
>>
>>   #include <drm/drm_print.h>
>>   #include <drm/drm_debugfs.h>
>> +#include <kunit/visibility.h>
>>
>>   #include "vkms_config.h"
>>
>> @@ -17,11 +18,13 @@ struct vkms_config *vkms_config_create(void)
>>
>>          return config;
>>   }
>> +EXPORT_SYMBOL_IF_KUNIT(vkms_config_create);
>>
>>   void vkms_config_destroy(struct vkms_config *config)
>>   {
>>          kfree(config);
>>   }
>> +EXPORT_SYMBOL_IF_KUNIT(vkms_config_destroy);
>>
>>   static int vkms_config_show(struct seq_file *m, void *data)
>>   {
>>
>> With this:
>>
>> Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>

-- 
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com