[PATCH v5 7/7] drm/vkms Add hotplug support via configfs to VKMS.

Brandon Pollack
2023-08-28T08:21:31Z

This change adds the ability to read or write a "1" or a "0" to the
newly added "connected" attribute of a connector in the vkms entry in
configfs.

A write will trigger a call to drm_kms_helper_hotplug_event, causing a
hotplug uevent.

With this we can write virtualized multidisplay tests that involve
hotplugging displays (eg recompositing windows when a monitor is turned
off).

Signed-off-by: Brandon Pollack <brpol@chromium.org>
---
Documentation/gpu/vkms.rst | 2 +-
drivers/gpu/drm/vkms/vkms_configfs.c | 68 ++++++++++++++++++++++++++--
drivers/gpu/drm/vkms/vkms_drv.h | 11 +++++
drivers/gpu/drm/vkms/vkms_output.c | 47 ++++++++++++++++++-
4 files changed, 123 insertions(+), 5 deletions(-)

diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index c3875bf66dba..7f715097539c 100644
--- a/Documentation/gpu/vkms.rst
+++ b/Documentation/gpu/vkms.rst
@@ -145,7 +145,7 @@ We want to be able to manipulate vkms instances without having to reload the
module. Such configuration can be added as extensions to vkms's ConfigFS
support. Use-cases:

-- Hotplug/hotremove connectors on the fly (to be able to test DP MST handling
+- Hotremove connectors on the fly (to be able to test DP MST handling
of compositors).

- Change output configuration: Plug/unplug screens, change EDID, allow changing
diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index c28fa87c196e..fd97511c394f 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0+

+#include "drm/drm_probe_helper.h"
#include <linux/configfs.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
@@ -40,6 +41,7 @@
* `-- vkms
* `-- test
* |-- connectors
+ * `-- connected
* |-- crtcs
* |-- encoders
* |-- planes
@@ -89,6 +91,14 @@
*
* echo 1 > /config/vkms/test/enabled
*
+ * By default no display is "connected" so to connect a connector you'll also
+ * have to write 1 to a connectors "connected" attribute::
+ *
+ * echo 1 > /config/vkms/test/connectors/connector/connected
+ *
+ * One can verify that this is worked using the `modetest` utility or the
+ * equivalent for your platform.
+ *
* When you're done with the virtual device, you can clean up the device like
* so::
*
@@ -234,7 +244,58 @@ static void add_possible_encoders(struct config_group *parent,

/* Connector item, e.g. /config/vkms/device/connectors/ID */

+static ssize_t connector_connected_show(struct config_item *item, char *buf)
+{
+ struct vkms_config_connector *connector =
+ item_to_config_connector(item);
+ struct vkms_configfs *configfs = connector_item_to_configfs(item);
+ bool connected = false;
+
+ mutex_lock(&configfs->lock);
+ connected = connector->connected;
+ mutex_unlock(&configfs->lock);
+
+ return sprintf(buf, "%d\n", connected);
+}
+
+static ssize_t connector_connected_store(struct config_item *item,
+ const char *buf, size_t len)
+{
+ struct vkms_config_connector *connector =
+ item_to_config_connector(item);
+ struct vkms_configfs *configfs = connector_item_to_configfs(item);
+ int val, ret;
+
+ ret = kstrtouint(buf, 10, &val);
+ if (ret)
+ return ret;
+
+ if (val != 1 && val != 0)
+ return -EINVAL;
+
+ mutex_lock(&configfs->lock);
+ connector->connected = val;
+ if (!connector->connector) {
+ pr_info("VKMS Device %s is not yet enabled, connector will be enabled on start",
+ configfs->device_group.cg_item.ci_name);
+ }
+ mutex_unlock(&configfs->lock);
+
+ if (connector->connector)
+ drm_kms_helper_hotplug_event(connector->connector->dev);
+
+ return len;
+}
+
+CONFIGFS_ATTR(connector_, connected);
+
+static struct configfs_attribute *connector_attrs[] = {
+ &connector_attr_connected,
+ NULL,
+};
+
static struct config_item_type connector_type = {
+ .ct_attrs = connector_attrs,
.ct_owner = THIS_MODULE,
};

@@ -262,7 +323,7 @@ static ssize_t plane_type_show(struct config_item *item, char *buf)
plane_type = plane->type;
mutex_unlock(&configfs->lock);

- return sprintf(buf, "%u", plane_type);
+ return sprintf(buf, "%u\n", plane_type);
}

static ssize_t plane_type_store(struct config_item *item, const char *buf,
@@ -317,6 +378,7 @@ static struct config_group *connectors_group_make(struct config_group *group,
&connector_type);
add_possible_encoders(&connector->config_group,
&connector->possible_encoders.group);
+ connector->connected = false;

return &connector->config_group;
}
@@ -498,7 +560,7 @@ static ssize_t device_enabled_show(struct config_item *item, char *buf)
is_enabled = configfs->vkms_device != NULL;
mutex_unlock(&configfs->lock);

- return sprintf(buf, "%d", is_enabled);
+ return sprintf(buf, "%d\n", is_enabled);
}

static ssize_t device_enabled_store(struct config_item *item, const char *buf,
@@ -555,7 +617,7 @@ static ssize_t device_id_show(struct config_item *item, char *buf)

mutex_unlock(&configfs->lock);

- return sprintf(buf, "%d", id);
+ return sprintf(buf, "%d\n", id);
}

CONFIGFS_ATTR_RO(device_, id);
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index 2b9545ada9c2..5336281f397e 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -3,6 +3,7 @@
#ifndef _VKMS_DRV_H_
#define _VKMS_DRV_H_

+#include "drm/drm_connector.h"
#include <linux/configfs.h>
#include <linux/hrtimer.h>

@@ -147,7 +148,9 @@ struct vkms_config_links {

struct vkms_config_connector {
struct config_group config_group;
+ struct drm_connector *connector;
struct vkms_config_links possible_encoders;
+ bool connected;
};

struct vkms_config_crtc {
@@ -220,6 +223,10 @@ struct vkms_device {
#define item_to_configfs(item) \
container_of(to_config_group(item), struct vkms_configfs, device_group)

+#define connector_item_to_configfs(item) \
+ container_of(to_config_group(item->ci_parent), struct vkms_configfs, \
+ connectors_group)
+
#define item_to_config_connector(item) \
container_of(to_config_group(item), struct vkms_config_connector, \
config_group)
@@ -279,4 +286,8 @@ int vkms_enable_writeback_connector(struct vkms_device *vkmsdev,
int vkms_init_configfs(void);
void vkms_unregister_configfs(void);

+/* Connector hotplugging */
+enum drm_connector_status vkms_connector_detect(struct drm_connector *connector,
+ bool force);
+
#endif /* _VKMS_DRV_H_ */
diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
index 883862e2c5f2..360765df2bbe 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 <drm/drm_print.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_connector.h>
#include <drm/drm_crtc.h>
@@ -8,10 +9,12 @@
#include <drm/drm_plane.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_simple_kms_helper.h>
+#include <linux/printk.h>

#include "vkms_drv.h"

static const struct drm_connector_funcs vkms_connector_funcs = {
+ .detect = vkms_connector_detect,
.fill_modes = drm_helper_probe_single_connector_modes,
.destroy = drm_connector_cleanup,
.reset = drm_atomic_helper_connector_reset,
@@ -19,6 +22,48 @@ static const struct drm_connector_funcs vkms_connector_funcs = {
.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
};

+static const struct vkms_config_connector *
+find_config_for_connector(struct drm_connector *connector)
+{
+ struct vkms_device *vkms = drm_device_to_vkms_device(connector->dev);
+ struct vkms_configfs *configfs = vkms->configfs;
+ struct config_item *item;
+
+ if (!configfs) {
+ pr_info("Default connector has no configfs entry");
+ return NULL;
+ }
+
+ list_for_each_entry(item, &configfs->connectors_group.cg_children,
+ ci_entry) {
+ struct vkms_config_connector *config_connector =
+ item_to_config_connector(item);
+ if (config_connector->connector == connector)
+ return config_connector;
+ }
+
+ pr_warn("Could not find config to match connector %s, but configfs was initialized",
+ connector->name);
+
+ return NULL;
+}
+
+enum drm_connector_status vkms_connector_detect(struct drm_connector *connector,
+ bool force)
+{
+ enum drm_connector_status status = connector_status_connected;
+ const struct vkms_config_connector *config_connector =
+ find_config_for_connector(connector);
+
+ if (!config_connector)
+ return connector_status_connected;
+
+ if (!config_connector->connected)
+ status = connector_status_disconnected;
+
+ return status;
+}
+
static const struct drm_encoder_funcs vkms_encoder_funcs = {
.destroy = drm_encoder_cleanup,
};
@@ -281,12 +326,12 @@ int vkms_output_init(struct vkms_device *vkmsdev)
struct vkms_config_connector *config_connector =
item_to_config_connector(item);
struct drm_connector *connector = vkms_connector_init(vkmsdev);
-
if (IS_ERR(connector)) {
DRM_ERROR("Failed to init connector from config: %s",
item->ci_name);
return PTR_ERR(connector);
}
+ config_connector->connector = connector;

for (int j = 0; j < output->num_encoders; j++) {
struct encoder_map *encoder = &encoder_map[j];
--
2.42.0.rc1.204.g551eb34607-goog