Re: [PATCH] [PATCH v3] usb: gadget: f_uac2: uevent changes for uac2

From: Greg Kroah-Hartman
Date: Sun Sep 17 2023 - 06:18:32 EST

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On Tue, Aug 29, 2023 at 02:51:32PM +0530, Akash Kumar wrote:
> Adding uevent from usb audio gadget driver for uac2 playback/capture
> events, which userspace reads and later reads sysfs entry to know if
> playback or capture has stopped or started by host application.
>
> /config/usb_gadget/g1/functions/uac2.0 # cat c_status
> 1 --> capture started
> 0 --> capture stopped
> /config/usb_gadget/g1/functions/uac2.0 # cat p_status
> 1 --> playback started
> 0 --> playback stopped
>
> Signed-off-by: Akash Kumar <quic_akakum@xxxxxxxxxxx>
> ---
> Documentation/usb/gadget-testing.rst | 6 ++++
> drivers/usb/gadget/function/f_uac2.c | 47 ++++++++++++++++++++++++++++
> drivers/usb/gadget/function/u_uac2.h | 5 +++
> 3 files changed, 58 insertions(+)
>
> diff --git a/Documentation/usb/gadget-testing.rst b/Documentation/usb/gadget-testing.rst
> index 2eeb3e9299e4..b2fded232ced 100644
> --- a/Documentation/usb/gadget-testing.rst
> +++ b/Documentation/usb/gadget-testing.rst
> @@ -733,6 +733,12 @@ The uac2 function provides these attributes in its function directory:
> p_ssize playback sample size (bytes)
> req_number the number of pre-allocated request for both capture
> and playback
> + c_status audio capture state
> + (0: capture stopped, 1: capture started)
> + p_status audio playback state
> + (0: playback stopped, 1: playback started)
> + c_status audio capture state
> + p_status audio playback state

spaces not tabs?

And shouldn't this also be documented in Documentation/ABI/ as well with
the other attributes?

> =============== ====================================================
>
> The attributes have sane default values.
> diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
> index db2d4980cb35..f1f7631e9380 100644
> --- a/drivers/usb/gadget/function/f_uac2.c
> +++ b/drivers/usb/gadget/function/f_uac2.c
> @@ -739,6 +739,8 @@ afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
> struct usb_gadget *gadget = cdev->gadget;
> struct device *dev = &gadget->dev;
> int ret = 0;
> + struct f_uac2_opts *audio_opts =
> + container_of(fn->fi, struct f_uac2_opts, func_inst);

Why assign it here and not below?

>
> /* No i/f has more than 2 alt settings */
> if (alt > 1) {
> @@ -762,6 +764,8 @@ afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
> ret = u_audio_start_capture(&uac2->g_audio);
> else
> u_audio_stop_capture(&uac2->g_audio);
> + audio_opts->c_status = alt;
> + schedule_work(&audio_opts->work);

You are changing functionality here, not just adding statistics, why is
work needed here?

> } else if (intf == uac2->as_in_intf) {
> uac2->as_in_alt = alt;
>
> @@ -769,6 +773,8 @@ afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
> ret = u_audio_start_playback(&uac2->g_audio);
> else
> u_audio_stop_playback(&uac2->g_audio);
> + audio_opts->p_status = alt;
> + schedule_work(&audio_opts->work);

Same here?

> } else {
> dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
> return -EINVAL;
> @@ -801,11 +807,16 @@ static void
> afunc_disable(struct usb_function *fn)
> {
> struct f_uac2 *uac2 = func_to_uac2(fn);
> + struct f_uac2_opts *audio_opts =
> + container_of(fn->fi, struct f_uac2_opts, func_inst);

Normally the bigger line goes at top.

>
> uac2->as_in_alt = 0;
> uac2->as_out_alt = 0;
> + audio_opts->p_status = 0;//alt;
> + audio_opts->c_status = 0; //alt;

You didn't actually mean to do this, right?

Please get review from someone else in your group before sending this
out for us to find obvious problems.

> u_audio_stop_capture(&uac2->g_audio);
> u_audio_stop_playback(&uac2->g_audio);
> + schedule_work(&audio_opts->work);
> }
>
> static int
> @@ -1036,6 +1047,25 @@ UAC2_ATTRIBUTE(c_srate);
> UAC2_ATTRIBUTE(c_ssize);
> UAC2_ATTRIBUTE(req_number);
>
> +#define UAC2_ATTRIBUTE_RO(name) \
> + static ssize_t f_uac2_opts_##name##_show( \
> + struct config_item *item, \
> + char *page) \
> +{ \
> + struct f_uac2_opts *opts = to_f_uac2_opts(item); \
> + int result; \
> + \
> + mutex_lock(&opts->lock); \
> + result = scnprintf(page, PAGE_SIZE, "%u\n", opts->name); \
> + mutex_unlock(&opts->lock); \
> + \
> + return result; \
> +} \
> +CONFIGFS_ATTR_RO(f_uac2_opts_, name)
> +
> +UAC2_ATTRIBUTE_RO(c_status);
> +UAC2_ATTRIBUTE_RO(p_status);
> +
> static struct configfs_attribute *f_uac2_attrs[] = {
> &f_uac2_opts_attr_p_chmask,
> &f_uac2_opts_attr_p_srate,
> @@ -1044,6 +1074,8 @@ static struct configfs_attribute *f_uac2_attrs[] = {
> &f_uac2_opts_attr_c_srate,
> &f_uac2_opts_attr_c_ssize,
> &f_uac2_opts_attr_req_number,
> + &f_uac2_opts_attr_c_status,
> + &f_uac2_opts_attr_p_status,
> NULL,
> };
>
> @@ -1053,11 +1085,23 @@ static const struct config_item_type f_uac2_func_type = {
> .ct_owner = THIS_MODULE,
> };
>
> +static void f_uac2_audio_status_change_work(struct work_struct *data)
> +{
> + struct f_uac2_opts *audio_opts =
> + container_of(data, struct f_uac2_opts, work);
> + char *envp[2] = { "UAC2_STATE=Changed", NULL };
> +
> + kobject_uevent_env(&audio_opts->device->kobj,
> + KOBJ_CHANGE, envp);
> +}
> +
> static void afunc_free_inst(struct usb_function_instance *f)
> {
> struct f_uac2_opts *opts;
>
> opts = container_of(f, struct f_uac2_opts, func_inst);
> + device_destroy(opts->device->class, opts->device->devt);

Wait, why?

> + cancel_work_sync(&opts->work);
> kfree(opts);
> }
>
> @@ -1082,6 +1126,9 @@ static struct usb_function_instance *afunc_alloc_inst(void)
> opts->c_srate = UAC2_DEF_CSRATE;
> opts->c_ssize = UAC2_DEF_CSSIZE;
> opts->req_number = UAC2_DEF_REQ_NUM;
> + INIT_WORK(&opts->work, f_uac2_audio_status_change_work);
> + opts->device = create_function_device("f_uac2");

A whole new device? Why? There should already be a device for this, if
not, you now need to document your new device as this is a whole new
thing for sysfs to show, right?

> +
> return &opts->func_inst;
> }
>
> diff --git a/drivers/usb/gadget/function/u_uac2.h b/drivers/usb/gadget/function/u_uac2.h
> index b5035711172d..3ccf2eb002f1 100644
> --- a/drivers/usb/gadget/function/u_uac2.h
> +++ b/drivers/usb/gadget/function/u_uac2.h
> @@ -36,6 +36,11 @@ struct f_uac2_opts {
>
> struct mutex lock;
> int refcnt;
> + int c_status;
> + int p_status;
> + struct device *device;
> + struct work_struct work;

Some documentation please for what these new fields are for.

thanks,

greg k-h

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