Add a list of CRTCs to vkms_config and helper functions to add and
remove as many CRTCs as wanted.

For backwards compatibility, add one CRTC to the default configuration.

A future patch will allow to attach planes and CRTCs, but for the
moment there are no changes in the way the output is configured.

Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
---
 drivers/gpu/drm/vkms/tests/vkms_config_test.c | 72 +++++++++++++++-
 drivers/gpu/drm/vkms/vkms_config.c            | 86 ++++++++++++++++++-
 drivers/gpu/drm/vkms/vkms_config.h            | 83 ++++++++++++++++++
 drivers/gpu/drm/vkms/vkms_drv.c               |  3 +-
 4 files changed, 238 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/vkms/tests/vkms_config_test.c b/drivers/gpu/drm/vkms/tests/vkms_config_test.c
index 7d9cb3956741..b5907b060a5c 100644
--- a/drivers/gpu/drm/vkms/tests/vkms_config_test.c
+++ b/drivers/gpu/drm/vkms/tests/vkms_config_test.c
@@ -25,6 +25,7 @@ static void vkms_config_test_empty_config(struct kunit *test)
 	KUNIT_EXPECT_STREQ(test, vkms_config_get_device_name(config), "test");
 
 	KUNIT_EXPECT_TRUE(test, list_empty(&config->planes));
+	KUNIT_EXPECT_TRUE(test, list_empty(&config->crtcs));
 
 	KUNIT_EXPECT_FALSE(test, vkms_config_is_valid(config));
 
@@ -49,6 +50,7 @@ static void vkms_config_test_default_config(struct kunit *test)
 	const struct default_config_case *params = test->param_value;
 	struct vkms_config *config;
 	struct vkms_config_plane *plane_cfg;
+	struct vkms_config_crtc *crtc_cfg;
 	int n_primaries = 0;
 	int n_cursors = 0;
 	int n_overlays = 0;
@@ -58,8 +60,6 @@ static void vkms_config_test_default_config(struct kunit *test)
 					    params->enable_overlay);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, config);
 
-	KUNIT_EXPECT_EQ(test, config->writeback, params->enable_writeback);
-
 	/* Planes */
 	list_for_each_entry(plane_cfg, &config->planes, link) {
 		switch (vkms_config_plane_get_type(plane_cfg)) {
@@ -80,6 +80,13 @@ static void vkms_config_test_default_config(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, n_cursors, params->enable_cursor ? 1 : 0);
 	KUNIT_EXPECT_EQ(test, n_overlays, params->enable_overlay ? 8 : 0);
 
+	/* CRTCs */
+	crtc_cfg = list_first_entry(&config->crtcs, typeof(*crtc_cfg), link);
+
+	KUNIT_EXPECT_EQ(test, list_count_nodes(&config->crtcs), 1);
+	KUNIT_EXPECT_EQ(test, vkms_config_crtc_get_writeback(crtc_cfg),
+			params->enable_writeback);
+
 	KUNIT_EXPECT_TRUE(test, vkms_config_is_valid(config));
 
 	vkms_config_destroy(config);
@@ -121,6 +128,42 @@ static void vkms_config_test_get_planes(struct kunit *test)
 	vkms_config_destroy(config);
 }
 
+static void vkms_config_test_get_crtcs(struct kunit *test)
+{
+	struct vkms_config *config;
+	struct vkms_config_crtc *crtc_cfg1, *crtc_cfg2;
+	struct vkms_config_crtc **array;
+	size_t length;
+
+	config = vkms_config_create("test");
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, config);
+
+	array = vkms_config_get_crtcs(config, &length);
+	KUNIT_ASSERT_EQ(test, length, 0);
+	KUNIT_ASSERT_NULL(test, array);
+
+	crtc_cfg1 = vkms_config_add_crtc(config);
+	array = vkms_config_get_crtcs(config, &length);
+	KUNIT_ASSERT_EQ(test, length, 1);
+	KUNIT_ASSERT_PTR_EQ(test, array[0], crtc_cfg1);
+	kfree(array);
+
+	crtc_cfg2 = vkms_config_add_crtc(config);
+	array = vkms_config_get_crtcs(config, &length);
+	KUNIT_ASSERT_EQ(test, length, 2);
+	KUNIT_ASSERT_PTR_EQ(test, array[0], crtc_cfg1);
+	KUNIT_ASSERT_PTR_EQ(test, array[1], crtc_cfg2);
+	kfree(array);
+
+	vkms_config_destroy_crtc(config, crtc_cfg2);
+	array = vkms_config_get_crtcs(config, &length);
+	KUNIT_ASSERT_EQ(test, length, 1);
+	KUNIT_ASSERT_PTR_EQ(test, array[0], crtc_cfg1);
+	kfree(array);
+
+	vkms_config_destroy(config);
+}
+
 static void vkms_config_test_valid_plane_number(struct kunit *test)
 {
 	struct vkms_config *config;
@@ -185,13 +228,38 @@ static void vkms_config_test_valid_plane_type(struct kunit *test)
 	vkms_config_destroy(config);
 }
 
+static void vkms_config_test_valid_crtc_number(struct kunit *test)
+{
+	struct vkms_config *config;
+	struct vkms_config_crtc *crtc_cfg;
+	int n;
+
+	config = vkms_config_default_create(false, false, false);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, config);
+
+	/* Invalid: No CRTCs */
+	crtc_cfg = list_first_entry(&config->crtcs, typeof(*crtc_cfg), link);
+	vkms_config_destroy_crtc(config, crtc_cfg);
+	KUNIT_EXPECT_FALSE(test, vkms_config_is_valid(config));
+
+	/* Invalid: Too many CRTCs */
+	for (n = 0; n <= 32; n++)
+		vkms_config_add_crtc(config);
+
+	KUNIT_EXPECT_FALSE(test, vkms_config_is_valid(config));
+
+	vkms_config_destroy(config);
+}
+
 static struct kunit_case vkms_config_test_cases[] = {
 	KUNIT_CASE(vkms_config_test_empty_config),
 	KUNIT_CASE_PARAM(vkms_config_test_default_config,
 			 default_config_gen_params),
 	KUNIT_CASE(vkms_config_test_get_planes),
+	KUNIT_CASE(vkms_config_test_get_crtcs),
 	KUNIT_CASE(vkms_config_test_valid_plane_number),
 	KUNIT_CASE(vkms_config_test_valid_plane_type),
+	KUNIT_CASE(vkms_config_test_valid_crtc_number),
 	{}
 };
 
diff --git a/drivers/gpu/drm/vkms/vkms_config.c b/drivers/gpu/drm/vkms/vkms_config.c
index a5a77612645f..4128892836d7 100644
--- a/drivers/gpu/drm/vkms/vkms_config.c
+++ b/drivers/gpu/drm/vkms/vkms_config.c
@@ -22,6 +22,7 @@ struct vkms_config *vkms_config_create(const char *dev_name)
 	}
 
 	INIT_LIST_HEAD(&config->planes);
+	INIT_LIST_HEAD(&config->crtcs);
 
 	return config;
 }
@@ -32,19 +33,23 @@ struct vkms_config *vkms_config_default_create(bool enable_cursor,
 {
 	struct vkms_config *config;
 	struct vkms_config_plane *plane_cfg;
+	struct vkms_config_crtc *crtc_cfg;
 	int n;
 
 	config = vkms_config_create(DEFAULT_DEVICE_NAME);
 	if (IS_ERR(config))
 		return config;
 
-	config->writeback = enable_writeback;
-
 	plane_cfg = vkms_config_add_plane(config);
 	if (IS_ERR(plane_cfg))
 		goto err_alloc;
 	vkms_config_plane_set_type(plane_cfg, DRM_PLANE_TYPE_PRIMARY);
 
+	crtc_cfg = vkms_config_add_crtc(config);
+	if (IS_ERR(crtc_cfg))
+		goto err_alloc;
+	vkms_config_crtc_set_writeback(crtc_cfg, enable_writeback);
+
 	if (enable_overlay) {
 		for (n = 0; n < NUM_OVERLAY_PLANES; n++) {
 			plane_cfg = vkms_config_add_plane(config);
@@ -72,10 +77,14 @@ struct vkms_config *vkms_config_default_create(bool enable_cursor,
 void vkms_config_destroy(struct vkms_config *config)
 {
 	struct vkms_config_plane *plane_cfg, *plane_tmp;
+	struct vkms_config_crtc *crtc_cfg, *crtc_tmp;
 
 	list_for_each_entry_safe(plane_cfg, plane_tmp, &config->planes, link)
 		vkms_config_destroy_plane(plane_cfg);
 
+	list_for_each_entry_safe(crtc_cfg, crtc_tmp, &config->crtcs, link)
+		vkms_config_destroy_crtc(config, crtc_cfg);
+
 	kfree_const(config->dev_name);
 	kfree(config);
 }
@@ -107,6 +116,33 @@ struct vkms_config_plane **vkms_config_get_planes(const struct vkms_config *conf
 	return array;
 }
 
+struct vkms_config_crtc **vkms_config_get_crtcs(const struct vkms_config *config,
+						size_t *out_length)
+{
+	struct vkms_config_crtc **array;
+	struct vkms_config_crtc *crtc_cfg;
+	size_t length;
+	int n = 0;
+
+	length = list_count_nodes((struct list_head *)&config->crtcs);
+	if (length == 0) {
+		*out_length = length;
+		return NULL;
+	}
+
+	array = kmalloc_array(length, sizeof(*array), GFP_KERNEL);
+	if (!array)
+		return ERR_PTR(-ENOMEM);
+
+	list_for_each_entry(crtc_cfg, &config->crtcs, link) {
+		array[n] = crtc_cfg;
+		n++;
+	}
+
+	*out_length = length;
+	return array;
+}
+
 static bool valid_plane_number(struct vkms_config *config)
 {
 	size_t n_planes;
@@ -156,11 +192,27 @@ static bool valid_plane_type(struct vkms_config *config)
 	return true;
 }
 
+static bool valid_crtc_number(struct vkms_config *config)
+{
+	size_t n_crtcs;
+
+	n_crtcs = list_count_nodes(&config->crtcs);
+	if (n_crtcs <= 0 || n_crtcs >= 32) {
+		pr_err("The number of CRTCs must be between 1 and 31\n");
+		return false;
+	}
+
+	return true;
+}
+
 bool vkms_config_is_valid(struct vkms_config *config)
 {
 	if (!valid_plane_number(config))
 		return false;
 
+	if (!valid_crtc_number(config))
+		return false;
+
 	if (!valid_plane_type(config))
 		return false;
 
@@ -174,10 +226,10 @@ static int vkms_config_show(struct seq_file *m, void *data)
 	struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev);
 	const char *dev_name;
 	struct vkms_config_plane *plane_cfg;
+	struct vkms_config_crtc *crtc_cfg;
 
 	dev_name = vkms_config_get_device_name((struct vkms_config *)vkmsdev->config);
 	seq_printf(m, "dev_name=%s\n", dev_name);
-	seq_printf(m, "writeback=%d\n", vkmsdev->config->writeback);
 
 	list_for_each_entry(plane_cfg, &vkmsdev->config->planes, link) {
 		seq_puts(m, "plane:\n");
@@ -185,6 +237,12 @@ static int vkms_config_show(struct seq_file *m, void *data)
 			   vkms_config_plane_get_type(plane_cfg));
 	}
 
+	list_for_each_entry(crtc_cfg, &vkmsdev->config->crtcs, link) {
+		seq_puts(m, "crtc:\n");
+		seq_printf(m, "\twriteback=%d\n",
+			   vkms_config_crtc_get_writeback(crtc_cfg));
+	}
+
 	return 0;
 }
 
@@ -218,3 +276,25 @@ void vkms_config_destroy_plane(struct vkms_config_plane *plane_cfg)
 	list_del(&plane_cfg->link);
 	kfree(plane_cfg);
 }
+
+struct vkms_config_crtc *vkms_config_add_crtc(struct vkms_config *config)
+{
+	struct vkms_config_crtc *crtc_cfg;
+
+	crtc_cfg = kzalloc(sizeof(*crtc_cfg), GFP_KERNEL);
+	if (!crtc_cfg)
+		return ERR_PTR(-ENOMEM);
+
+	vkms_config_crtc_set_writeback(crtc_cfg, false);
+
+	list_add_tail(&crtc_cfg->link, &config->crtcs);
+
+	return crtc_cfg;
+}
+
+void vkms_config_destroy_crtc(struct vkms_config *config,
+			      struct vkms_config_crtc *crtc_cfg)
+{
+	list_del(&crtc_cfg->link);
+	kfree(crtc_cfg);
+}
diff --git a/drivers/gpu/drm/vkms/vkms_config.h b/drivers/gpu/drm/vkms/vkms_config.h
index d9aeba1762d1..a7828fe0c4b2 100644
--- a/drivers/gpu/drm/vkms/vkms_config.h
+++ b/drivers/gpu/drm/vkms/vkms_config.h
@@ -14,12 +14,14 @@
  * @dev_name: Name of the device
  * @writeback: If true, a writeback buffer can be attached to the CRTC
  * @planes: List of planes configured for the device
+ * @crtcs: List of CRTCs configured for the device
  * @dev: Used to store the current VKMS device. Only set when the device is instantiated.
  */
 struct vkms_config {
 	const char *dev_name;
 	bool writeback;
 	struct list_head planes;
+	struct list_head crtcs;
 	struct vkms_device *dev;
 };
 
@@ -43,6 +45,25 @@ struct vkms_config_plane {
 	struct vkms_plane *plane;
 };
 
+/**
+ * struct vkms_config_crtc
+ *
+ * @link: Link to the others CRTCs in vkms_config
+ * @writeback: If true, a writeback buffer can be attached to the CRTC
+ * @crtc: Internal usage. This pointer should never be considered as valid.
+ *        It can be used to store a temporary reference to a VKMS CRTC during
+ *        device creation. This pointer is not managed by the configuration and
+ *        must be managed by other means.
+ */
+struct vkms_config_crtc {
+	struct list_head link;
+
+	bool writeback;
+
+	/* Internal usage */
+	struct vkms_output *crtc;
+};
+
 /**
  * vkms_config_create() - Create a new VKMS configuration
  * @dev_name: Name of the device
@@ -96,6 +117,28 @@ vkms_config_get_device_name(struct vkms_config *config)
 struct vkms_config_plane **vkms_config_get_planes(const struct vkms_config *config,
 						  size_t *out_length);
 
+/**
+ * vkms_config_get_num_crtcs() - Return the number of CRTCs in the configuration
+ * @config: Configuration to get the number of CRTCs from
+ */
+static inline size_t vkms_config_get_num_crtcs(struct vkms_config *config)
+{
+	return list_count_nodes(&config->crtcs);
+}
+
+/**
+ * vkms_config_get_crtcs() - Return the array of CRTCs of the device
+ * @config: Configuration to get the CRTCs from
+ * @out_length: Length of the returned array
+ *
+ * Returns:
+ * A list of pointers to the configurations. On success, the caller is
+ * responsible to free the returned array, but not its contents. On error,
+ * it returns an error and @out_length is invalid.
+ */
+struct vkms_config_crtc **vkms_config_get_crtcs(const struct vkms_config *config,
+						size_t *out_length);
+
 /**
  * vkms_config_is_valid() - Validate a configuration
  * @config: Configuration to validate
@@ -151,4 +194,44 @@ vkms_config_plane_set_type(struct vkms_config_plane *plane_cfg,
 	plane_cfg->type = type;
 }
 
+/**
+ * vkms_config_add_crtc() - Add a new CRTC configuration
+ * @config: Configuration to add the CRTC to
+ *
+ * Returns:
+ * The new CRTC configuration or an error. Call vkms_config_destroy_crtc() to
+ * free the returned CRTC configuration.
+ */
+struct vkms_config_crtc *vkms_config_add_crtc(struct vkms_config *config);
+
+/**
+ * vkms_config_destroy_crtc() - Remove and free a CRTC configuration
+ * @config: Configuration to remove the CRTC from
+ * @crtc_cfg: CRTC configuration to destroy
+ */
+void vkms_config_destroy_crtc(struct vkms_config *config,
+			      struct vkms_config_crtc *crtc_cfg);
+
+/**
+ * vkms_config_crtc_get_writeback() - If a writeback connector will be created
+ * @crtc_cfg: CRTC with or without a writeback connector
+ */
+static inline bool
+vkms_config_crtc_get_writeback(struct vkms_config_crtc *crtc_cfg)
+{
+	return crtc_cfg->writeback;
+}
+
+/**
+ * vkms_config_crtc_set_writeback() - If a writeback connector will be created
+ * @crtc_cfg: Target CRTC
+ * @writeback: Enable or disable the writeback connector
+ */
+static inline void
+vkms_config_crtc_set_writeback(struct vkms_config_crtc *crtc_cfg,
+			       bool writeback)
+{
+	crtc_cfg->writeback = writeback;
+}
+
 #endif /* _VKMS_CONFIG_H_ */
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index f23ee1a053e9..77f24b802849 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -181,7 +181,8 @@ static int vkms_create(struct vkms_config *config)
 		goto out_devres;
 	}
 
-	ret = drm_vblank_init(&vkms_device->drm, 1);
+	ret = drm_vblank_init(&vkms_device->drm,
+			      vkms_config_get_num_crtcs(config));
 	if (ret) {
 		DRM_ERROR("Failed to vblank\n");
 		goto out_devres;
-- 
2.48.1

On 29/01/25 - 12:00, José Expósito wrote:
> Add a list of CRTCs to vkms_config and helper functions to add and
> remove as many CRTCs as wanted.
> 
> For backwards compatibility, add one CRTC to the default configuration.
> 
> A future patch will allow to attach planes and CRTCs, but for the
> moment there are no changes in the way the output is configured.
> 
> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> Signed-off-by: José Expósito <jose.exposito89@gmail.com>

Co-developped-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>

[...]

> diff --git a/drivers/gpu/drm/vkms/tests/vkms_config_test.c b/drivers/gpu/drm/vkms/tests/vkms_config_test.c

[...]

> +static void vkms_config_test_valid_crtc_number(struct kunit *test)
> +{
> +	struct vkms_config *config;
> +	struct vkms_config_crtc *crtc_cfg;
> +	int n;
> +
> +	config = vkms_config_default_create(false, false, false);
> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, config);
> +
> +	/* Invalid: No CRTCs */
> +	crtc_cfg = list_first_entry(&config->crtcs, typeof(*crtc_cfg), link);
> +	vkms_config_destroy_crtc(config, crtc_cfg);
> +	KUNIT_EXPECT_FALSE(test, vkms_config_is_valid(config));
> +
> +	/* Invalid: Too many CRTCs */
> +	for (n = 0; n <= 32; n++)
> +		vkms_config_add_crtc(config);
> +
> +	KUNIT_EXPECT_FALSE(test, vkms_config_is_valid(config));
> +
> +	vkms_config_destroy(config);
> +}

Same as before, can you rename the fonction to 
vkms_config_test_invalid_crtc_number

[...]

> diff --git a/drivers/gpu/drm/vkms/vkms_config.c b/drivers/gpu/drm/vkms/vkms_config.c

[...]

> +struct vkms_config_crtc **vkms_config_get_crtcs(const struct vkms_config *config,
> +						size_t *out_length)
> +{
> +	struct vkms_config_crtc **array;
> +	struct vkms_config_crtc *crtc_cfg;
> +	size_t length;
> +	int n = 0;
> +
> +	length = list_count_nodes((struct list_head *)&config->crtcs);
> +	if (length == 0) {
> +		*out_length = length;
> +		return NULL;
> +	}
> +
> +	array = kmalloc_array(length, sizeof(*array), GFP_KERNEL);
> +	if (!array)
> +		return ERR_PTR(-ENOMEM);
> +
> +	list_for_each_entry(crtc_cfg, &config->crtcs, link) {
> +		array[n] = crtc_cfg;
> +		n++;
> +	}
> +
> +	*out_length = length;
> +	return array;
> +}

Same as before, can't we use an iterator?

[...]

> +static bool valid_crtc_number(struct vkms_config *config)
> +{
> +	size_t n_crtcs;
> +
> +	n_crtcs = list_count_nodes(&config->crtcs);
> +	if (n_crtcs <= 0 || n_crtcs >= 32) {
> +		pr_err("The number of CRTCs must be between 1 and 31\n");

I agree we need some logs, but I think pr_err is too agressive (i.e may 
be considered as an error by some test tools).

I think we should at least:
- lower to warn/notice/info
- use drm variants of the macro

> +		return false;
> +	}
> +
> +	return true;
> +}
> +

[...]

> +struct vkms_config_crtc *vkms_config_add_crtc(struct vkms_config *config)
> +{
> +	struct vkms_config_crtc *crtc_cfg;
> +
> +	crtc_cfg = kzalloc(sizeof(*crtc_cfg), GFP_KERNEL);
> +	if (!crtc_cfg)
> +		return ERR_PTR(-ENOMEM);
> +
> +	vkms_config_crtc_set_writeback(crtc_cfg, false);
> +
> +	list_add_tail(&crtc_cfg->link, &config->crtcs);
> +
> +	return crtc_cfg;
> +}
> +
> +void vkms_config_destroy_crtc(struct vkms_config *config,
> +			      struct vkms_config_crtc *crtc_cfg)
> +{
> +	list_del(&crtc_cfg->link);
> +	kfree(crtc_cfg);
> +}

Same as before, the pair add/destroy seems strange.

> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -181,7 +181,8 @@ static int vkms_create(struct vkms_config *config)
>  		goto out_devres;
>  	}
>  
> -	ret = drm_vblank_init(&vkms_device->drm, 1);
> +	ret = drm_vblank_init(&vkms_device->drm,
> +			      vkms_config_get_num_crtcs(config));

At this point we only create one crtc, can you move this change in the 
commit where you create multiple crtc?

>  	if (ret) {
>  		DRM_ERROR("Failed to vblank\n");
>  		goto out_devres;
> -- 
> 2.48.1
> 

On Thu, Jan 30, 2025 at 02:48:20PM +0100, Louis Chauvet wrote:
> On 29/01/25 - 12:00, José Expósito wrote:
> > Add a list of CRTCs to vkms_config and helper functions to add and
> > remove as many CRTCs as wanted.
> > 
> > For backwards compatibility, add one CRTC to the default configuration.
> > 
> > A future patch will allow to attach planes and CRTCs, but for the
> > moment there are no changes in the way the output is configured.
> > 
> > Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> > Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> 
> Co-developped-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>
> 
> [...]
> 
> > diff --git a/drivers/gpu/drm/vkms/tests/vkms_config_test.c b/drivers/gpu/drm/vkms/tests/vkms_config_test.c
> 
> [...]
> 
> > +static void vkms_config_test_valid_crtc_number(struct kunit *test)
> > +{
> > +	struct vkms_config *config;
> > +	struct vkms_config_crtc *crtc_cfg;
> > +	int n;
> > +
> > +	config = vkms_config_default_create(false, false, false);
> > +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, config);
> > +
> > +	/* Invalid: No CRTCs */
> > +	crtc_cfg = list_first_entry(&config->crtcs, typeof(*crtc_cfg), link);
> > +	vkms_config_destroy_crtc(config, crtc_cfg);
> > +	KUNIT_EXPECT_FALSE(test, vkms_config_is_valid(config));
> > +
> > +	/* Invalid: Too many CRTCs */
> > +	for (n = 0; n <= 32; n++)
> > +		vkms_config_add_crtc(config);
> > +
> > +	KUNIT_EXPECT_FALSE(test, vkms_config_is_valid(config));
> > +
> > +	vkms_config_destroy(config);
> > +}
> 
> Same as before, can you rename the fonction to 
> vkms_config_test_invalid_crtc_number
> 
> [...]
> 
> > diff --git a/drivers/gpu/drm/vkms/vkms_config.c b/drivers/gpu/drm/vkms/vkms_config.c
> 
> [...]
> 
> > +struct vkms_config_crtc **vkms_config_get_crtcs(const struct vkms_config *config,
> > +						size_t *out_length)
> > +{
> > +	struct vkms_config_crtc **array;
> > +	struct vkms_config_crtc *crtc_cfg;
> > +	size_t length;
> > +	int n = 0;
> > +
> > +	length = list_count_nodes((struct list_head *)&config->crtcs);
> > +	if (length == 0) {
> > +		*out_length = length;
> > +		return NULL;
> > +	}
> > +
> > +	array = kmalloc_array(length, sizeof(*array), GFP_KERNEL);
> > +	if (!array)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	list_for_each_entry(crtc_cfg, &config->crtcs, link) {
> > +		array[n] = crtc_cfg;
> > +		n++;
> > +	}
> > +
> > +	*out_length = length;
> > +	return array;
> > +}
> 
> Same as before, can't we use an iterator?
> 
> [...]
> 
> > +static bool valid_crtc_number(struct vkms_config *config)
> > +{
> > +	size_t n_crtcs;
> > +
> > +	n_crtcs = list_count_nodes(&config->crtcs);
> > +	if (n_crtcs <= 0 || n_crtcs >= 32) {
> > +		pr_err("The number of CRTCs must be between 1 and 31\n");
> 
> I agree we need some logs, but I think pr_err is too agressive (i.e may 
> be considered as an error by some test tools).
> 
> I think we should at least:
> - lower to warn/notice/info
> - use drm variants of the macro
> 
> > +		return false;
> > +	}
> > +
> > +	return true;
> > +}
> > +
> 
> [...]
> 
> > +struct vkms_config_crtc *vkms_config_add_crtc(struct vkms_config *config)
> > +{
> > +	struct vkms_config_crtc *crtc_cfg;
> > +
> > +	crtc_cfg = kzalloc(sizeof(*crtc_cfg), GFP_KERNEL);
> > +	if (!crtc_cfg)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	vkms_config_crtc_set_writeback(crtc_cfg, false);
> > +
> > +	list_add_tail(&crtc_cfg->link, &config->crtcs);
> > +
> > +	return crtc_cfg;
> > +}
> > +
> > +void vkms_config_destroy_crtc(struct vkms_config *config,
> > +			      struct vkms_config_crtc *crtc_cfg)
> > +{
> > +	list_del(&crtc_cfg->link);
> > +	kfree(crtc_cfg);
> > +}
> 
> Same as before, the pair add/destroy seems strange.
> 
> > +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> > @@ -181,7 +181,8 @@ static int vkms_create(struct vkms_config *config)
> >  		goto out_devres;
> >  	}
> >  
> > -	ret = drm_vblank_init(&vkms_device->drm, 1);
> > +	ret = drm_vblank_init(&vkms_device->drm,
> > +			      vkms_config_get_num_crtcs(config));
> 
> At this point we only create one crtc, can you move this change in the 
> commit where you create multiple crtc?

Since the code to add more than one CRTCs is unused but technically present, I
think that this is the right patch to use this function.

Anyway, at the moment it'll always return 1, so it is a no-op.

I didn't change it in v2, let me know if it works for you.

Thanks,
Jose

> >  	if (ret) {
> >  		DRM_ERROR("Failed to vblank\n");
> >  		goto out_devres;
> > -- 
> > 2.48.1
> > 

Le 11/02/2025 à 11:44, José Expósito a écrit :
> On Thu, Jan 30, 2025 at 02:48:20PM +0100, Louis Chauvet wrote:
>> On 29/01/25 - 12:00, José Expósito wrote:
>>> Add a list of CRTCs to vkms_config and helper functions to add and
>>> remove as many CRTCs as wanted.
>>>
>>> For backwards compatibility, add one CRTC to the default configuration.
>>>
>>> A future patch will allow to attach planes and CRTCs, but for the
>>> moment there are no changes in the way the output is configured.
>>>
>>> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
>>> Signed-off-by: José Expósito <jose.exposito89@gmail.com>
>>
>> Co-developped-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>
>>
>> [...]
>>
>>> diff --git a/drivers/gpu/drm/vkms/tests/vkms_config_test.c b/drivers/gpu/drm/vkms/tests/vkms_config_test.c
>>
>> [...]
>>
>>> +static void vkms_config_test_valid_crtc_number(struct kunit *test)
>>> +{
>>> +	struct vkms_config *config;
>>> +	struct vkms_config_crtc *crtc_cfg;
>>> +	int n;
>>> +
>>> +	config = vkms_config_default_create(false, false, false);
>>> +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, config);
>>> +
>>> +	/* Invalid: No CRTCs */
>>> +	crtc_cfg = list_first_entry(&config->crtcs, typeof(*crtc_cfg), link);
>>> +	vkms_config_destroy_crtc(config, crtc_cfg);
>>> +	KUNIT_EXPECT_FALSE(test, vkms_config_is_valid(config));
>>> +
>>> +	/* Invalid: Too many CRTCs */
>>> +	for (n = 0; n <= 32; n++)
>>> +		vkms_config_add_crtc(config);
>>> +
>>> +	KUNIT_EXPECT_FALSE(test, vkms_config_is_valid(config));
>>> +
>>> +	vkms_config_destroy(config);
>>> +}
>>
>> Same as before, can you rename the fonction to
>> vkms_config_test_invalid_crtc_number
>>
>> [...]
>>
>>> diff --git a/drivers/gpu/drm/vkms/vkms_config.c b/drivers/gpu/drm/vkms/vkms_config.c
>>
>> [...]
>>
>>> +struct vkms_config_crtc **vkms_config_get_crtcs(const struct vkms_config *config,
>>> +						size_t *out_length)
>>> +{
>>> +	struct vkms_config_crtc **array;
>>> +	struct vkms_config_crtc *crtc_cfg;
>>> +	size_t length;
>>> +	int n = 0;
>>> +
>>> +	length = list_count_nodes((struct list_head *)&config->crtcs);
>>> +	if (length == 0) {
>>> +		*out_length = length;
>>> +		return NULL;
>>> +	}
>>> +
>>> +	array = kmalloc_array(length, sizeof(*array), GFP_KERNEL);
>>> +	if (!array)
>>> +		return ERR_PTR(-ENOMEM);
>>> +
>>> +	list_for_each_entry(crtc_cfg, &config->crtcs, link) {
>>> +		array[n] = crtc_cfg;
>>> +		n++;
>>> +	}
>>> +
>>> +	*out_length = length;
>>> +	return array;
>>> +}
>>
>> Same as before, can't we use an iterator?
>>
>> [...]
>>
>>> +static bool valid_crtc_number(struct vkms_config *config)
>>> +{
>>> +	size_t n_crtcs;
>>> +
>>> +	n_crtcs = list_count_nodes(&config->crtcs);
>>> +	if (n_crtcs <= 0 || n_crtcs >= 32) {
>>> +		pr_err("The number of CRTCs must be between 1 and 31\n");
>>
>> I agree we need some logs, but I think pr_err is too agressive (i.e may
>> be considered as an error by some test tools).
>>
>> I think we should at least:
>> - lower to warn/notice/info
>> - use drm variants of the macro
>>
>>> +		return false;
>>> +	}
>>> +
>>> +	return true;
>>> +}
>>> +
>>
>> [...]
>>
>>> +struct vkms_config_crtc *vkms_config_add_crtc(struct vkms_config *config)
>>> +{
>>> +	struct vkms_config_crtc *crtc_cfg;
>>> +
>>> +	crtc_cfg = kzalloc(sizeof(*crtc_cfg), GFP_KERNEL);
>>> +	if (!crtc_cfg)
>>> +		return ERR_PTR(-ENOMEM);
>>> +
>>> +	vkms_config_crtc_set_writeback(crtc_cfg, false);
>>> +
>>> +	list_add_tail(&crtc_cfg->link, &config->crtcs);
>>> +
>>> +	return crtc_cfg;
>>> +}
>>> +
>>> +void vkms_config_destroy_crtc(struct vkms_config *config,
>>> +			      struct vkms_config_crtc *crtc_cfg)
>>> +{
>>> +	list_del(&crtc_cfg->link);
>>> +	kfree(crtc_cfg);
>>> +}
>>
>> Same as before, the pair add/destroy seems strange.
>>
>>> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
>>> @@ -181,7 +181,8 @@ static int vkms_create(struct vkms_config *config)
>>>   		goto out_devres;
>>>   	}
>>>   
>>> -	ret = drm_vblank_init(&vkms_device->drm, 1);
>>> +	ret = drm_vblank_init(&vkms_device->drm,
>>> +			      vkms_config_get_num_crtcs(config));
>>
>> At this point we only create one crtc, can you move this change in the
>> commit where you create multiple crtc?
> 
> Since the code to add more than one CRTCs is unused but technically present, I
> think that this is the right patch to use this function.

I don't totally agree: you can create multiple vkms_config_crtc, but the 
code only creates one drm_crtc.

For me it is more logical to keep 1 here, as the rest of the code only 
creates one CRTC. With the next patch, the code will create more than 
one CRTC, so it makes sense to use vkms_config_get_num_crtcs.

It is not a strong blocking point, but if a v3 is needed, could you 
change it?

> Anyway, at the moment it'll always return 1, so it is a no-op.

The current user is only default_config, so yes I agree, it is always 1.

> I didn't change it in v2, let me know if it works for you.
> 
> Thanks,
> Jose
> 
>>>   	if (ret) {
>>>   		DRM_ERROR("Failed to vblank\n");
>>>   		goto out_devres;
>>> -- 
>>> 2.48.1
>>>

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

Hey Louis,

On Wed, Feb 12, 2025 at 03:12:13PM +0100, Louis Chauvet wrote:
> 
> 
> Le 11/02/2025 à 11:44, José Expósito a écrit :
> > On Thu, Jan 30, 2025 at 02:48:20PM +0100, Louis Chauvet wrote:
> > > On 29/01/25 - 12:00, José Expósito wrote:
> > > > Add a list of CRTCs to vkms_config and helper functions to add and
> > > > remove as many CRTCs as wanted.
> > > > 
> > > > For backwards compatibility, add one CRTC to the default configuration.
> > > > 
> > > > A future patch will allow to attach planes and CRTCs, but for the
> > > > moment there are no changes in the way the output is configured.
> > > > 
> > > > Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> > > > Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> > > 
> > > Co-developped-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>
> > > 
> > > [...]
> > > 
> > > > +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> > > > @@ -181,7 +181,8 @@ static int vkms_create(struct vkms_config *config)
> > > >   		goto out_devres;
> > > >   	}
> > > > -	ret = drm_vblank_init(&vkms_device->drm, 1);
> > > > +	ret = drm_vblank_init(&vkms_device->drm,
> > > > +			      vkms_config_get_num_crtcs(config));
> > > 
> > > At this point we only create one crtc, can you move this change in the
> > > commit where you create multiple crtc?
> > 
> > Since the code to add more than one CRTCs is unused but technically present, I
> > think that this is the right patch to use this function.
> 
> I don't totally agree: you can create multiple vkms_config_crtc, but the
> code only creates one drm_crtc.
> 
> For me it is more logical to keep 1 here, as the rest of the code only
> creates one CRTC. With the next patch, the code will create more than one
> CRTC, so it makes sense to use vkms_config_get_num_crtcs.
> 
> It is not a strong blocking point, but if a v3 is needed, could you change
> it?

Fair enough, moved to the next patch in my local branch.

I'll send it in v3.

Jose

> > Anyway, at the moment it'll always return 1, so it is a no-op.
> 
> The current user is only default_config, so yes I agree, it is always 1.
> 
> > I didn't change it in v2, let me know if it works for you.
> > 
> > Thanks,
> > Jose
> > 
> > > >   	if (ret) {
> > > >   		DRM_ERROR("Failed to vblank\n");
> > > >   		goto out_devres;
> > > > -- 
> > > > 2.48.1
> > > > 
> 
> -- 
> Louis Chauvet, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>