On 08/01/2021 18:17, Ezequiel Garcia wrote:
> There is currently little to no information available
> about the reasons why a v4l2-async device hasn't
> probed completely.
>
> Inspired by the "devices_deferred" debugfs file,
> add a file to list information about the subdevices
> that are on waiting lists, for each notifier.
>
> This is useful to debug v4l2-async subdevices
> and notifiers, for instance when doing device bring-up.
>
> For instance, a typical output would be:
>
> $ cat /sys/kernel/debug/video4linux/pending_async_subdevices
> ipu1_csi1:
> [fwnode] dev=20e0000.iomuxc-gpr:ipu1_csi1_mux, node=/soc/bus@2000000/iomuxc-gpr@20e0000/ipu1_csi1_mux
> ipu1_csi0:
> [fwnode] dev=20e0000.iomuxc-gpr:ipu1_csi0_mux, node=/soc/bus@2000000/iomuxc-gpr@20e0000/ipu1_csi0_mux
> imx6-mipi-csi2:
> [fwnode] dev=1-003c, node=/soc/bus@2100000/i2c@21a4000/camera@3c
> imx-media:
>
> Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Nice, this should be quite useful.
Regards,
Hans
> --
> v3:
> * Drop MATCH_CUSTOM
> * Use the actual fwnode, to print the real full path. endpoint name.
> * Fix refcounted handle leak.
> v2:
> * Print fwnode path, as suggested by Sakari.
> * Print the subdevices under their corresponding notifier.
> * Rename the file as suggested by Laurent.
> ---
> drivers/media/v4l2-core/v4l2-async.c | 66 ++++++++++++++++++++++++++++
> drivers/media/v4l2-core/v4l2-dev.c | 5 +++
> include/media/v4l2-async.h | 8 ++++
> 3 files changed, 79 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> index 3faf1d12d49d..7c8a97205b3e 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -5,6 +5,7 @@
> * Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> */
>
> +#include <linux/debugfs.h>
> #include <linux/device.h>
> #include <linux/err.h>
> #include <linux/i2c.h>
> @@ -14,6 +15,7 @@
> #include <linux/mutex.h>
> #include <linux/of.h>
> #include <linux/platform_device.h>
> +#include <linux/seq_file.h>
> #include <linux/slab.h>
> #include <linux/types.h>
>
> @@ -823,3 +825,67 @@ void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
> mutex_unlock(&list_lock);
> }
> EXPORT_SYMBOL(v4l2_async_unregister_subdev);
> +
> +static void print_waiting_subdev(struct seq_file *s,
> + struct v4l2_async_subdev *asd)
> +{
> + switch (asd->match_type) {
> + case V4L2_ASYNC_MATCH_DEVNAME:
> + seq_printf(s, " [devname] dev=%s\n", asd->match.device_name);
> + break;
> + case V4L2_ASYNC_MATCH_I2C:
> + seq_printf(s, " [i2c] dev=%d-%04x\n", asd->match.i2c.adapter_id,
> + asd->match.i2c.address);
> + break;
> + case V4L2_ASYNC_MATCH_FWNODE: {
> + struct fwnode_handle *devnode, *fwnode = asd->match.fwnode;
> +
> + devnode = fwnode_graph_is_endpoint(fwnode) ?
> + fwnode_graph_get_port_parent(fwnode) :
> + fwnode_handle_get(fwnode);
> +
> + seq_printf(s, " [fwnode] dev=%s, node=%pfw\n",
> + devnode->dev ? dev_name(devnode->dev) : "nil",
> + fwnode);
> +
> + fwnode_handle_put(devnode);
> + break;
> + }
> + }
> +}
> +
> +static const char *
> +v4l2_async_notifier_name(struct v4l2_async_notifier *notifier)
> +{
> + if (notifier->v4l2_dev)
> + return notifier->v4l2_dev->name;
> + else if (notifier->sd)
> + return notifier->sd->name;
> + else
> + return "nil";
> +}
> +
> +static int pending_subdevs_show(struct seq_file *s, void *data)
> +{
> + struct v4l2_async_notifier *notif;
> + struct v4l2_async_subdev *asd;
> +
> + mutex_lock(&list_lock);
> +
> + list_for_each_entry(notif, ¬ifier_list, list) {
> + seq_printf(s, "%s:\n", v4l2_async_notifier_name(notif));
> + list_for_each_entry(asd, ¬if->waiting, list)
> + print_waiting_subdev(s, asd);
> + }
> +
> + mutex_unlock(&list_lock);
> +
> + return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(pending_subdevs);
> +
> +void v4l2_async_debug_init(struct dentry *debugfs_dir)
> +{
> + debugfs_create_file("pending_async_subdevices", 0444, debugfs_dir, NULL,
> + &pending_subdevs_fops);
> +}
> diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
> index a593ea0598b5..8d3813e6ab56 100644
> --- a/drivers/media/v4l2-core/v4l2-dev.c
> +++ b/drivers/media/v4l2-core/v4l2-dev.c
> @@ -14,6 +14,7 @@
>
> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>
> +#include <linux/debugfs.h>
> #include <linux/module.h>
> #include <linux/types.h>
> #include <linux/kernel.h>
> @@ -37,6 +38,7 @@
> __func__, ##arg); \
> } while (0)
>
> +static struct dentry *v4l2_debugfs_dir;
>
> /*
> * sysfs stuff
> @@ -1113,6 +1115,8 @@ static int __init videodev_init(void)
> return -EIO;
> }
>
> + v4l2_debugfs_dir = debugfs_create_dir("video4linux", NULL);
> + v4l2_async_debug_init(v4l2_debugfs_dir);
> return 0;
> }
>
> @@ -1120,6 +1124,7 @@ static void __exit videodev_exit(void)
> {
> dev_t dev = MKDEV(VIDEO_MAJOR, 0);
>
> + debugfs_remove_recursive(v4l2_debugfs_dir);
> class_unregister(&video_class);
> unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
> }
> diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> index 8ed42188e7c9..26296d4cb660 100644
> --- a/include/media/v4l2-async.h
> +++ b/include/media/v4l2-async.h
> @@ -11,6 +11,7 @@
> #include <linux/list.h>
> #include <linux/mutex.h>
>
> +struct dentry;
> struct device;
> struct device_node;
> struct v4l2_device;
> @@ -120,6 +121,13 @@ struct v4l2_async_notifier {
> struct list_head list;
> };
>
> +/**
> + * v4l2_async_debug_init - Initialize debugging tools.
> + *
> + * @debugfs_dir: pointer to the parent debugfs &struct dentry
> + */
> +void v4l2_async_debug_init(struct dentry *debugfs_dir);
> +
> /**
> * v4l2_async_notifier_init - Initialize a notifier.
> *
>
