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Date: Wed, 8 Mar 2023 19:15:39 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Elson Roy Serrao <quic_eserrao@...cinc.com>
CC: "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
"balbi@...nel.org" <balbi@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"quic_wcheng@...cinc.com" <quic_wcheng@...cinc.com>,
"quic_jackp@...cinc.com" <quic_jackp@...cinc.com>
Subject: Re: [PATCH v6 3/5] usb: gadget: Add function wakeup support
Hi Elson,
On Mon, Mar 06, 2023, Elson Roy Serrao wrote:
> A function which is in function suspend state has to send a
> function wake notification to the host in case it needs to
This should be rephrased. The device doesn't send wakeup device
notification while in suspend.
> exit from this state and resume data transfer. Add support to
> handle such requests by exposing a new gadget op.
Please provide more info in the commit message describing the change.
You did more than just adding a new gadget op here.
>
> Signed-off-by: Elson Roy Serrao <quic_eserrao@...cinc.com>
> ---
> drivers/usb/gadget/composite.c | 40 ++++++++++++++++++++++++++++++++++++++++
> include/linux/usb/composite.h | 6 ++++++
> include/linux/usb/gadget.h | 1 +
> 3 files changed, 47 insertions(+)
>
> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> index 7512854..7ae78c05 100644
> --- a/drivers/usb/gadget/composite.c
> +++ b/drivers/usb/gadget/composite.c
> @@ -492,6 +492,46 @@ int usb_interface_id(struct usb_configuration *config,
> }
> EXPORT_SYMBOL_GPL(usb_interface_id);
>
> +/**
> + * usb_func_wakeup - sends function wake notification to the host.
> + * @func: function that sends the remote wakeup notification.
> + *
> + * Applicable only to enhanced super speed devices when usb functions
Enhanced SuperSpeed devices can operate in usb2 speeds. This should be
rephased to refer to the operating speed instead.
> + * are put in function suspend state and armed for function remote wakeup.
> + * On completion, function wake notification is sent. If the device is in
> + * low power state it tries to bring the device to active state before
> + * sending the wake notification. Since it is a synchronous call, caller
> + * must take care of not calling it in interrupt context. For non enhanced
> + * super speed devices operating in lower speeds returns negative errno.
Same here. Enhanced SuperSpeed devices can operate in lower speeds.
It's a good idea that you discarded creating usb_gadget_func_wakeup().
In usb_gadget_wakeup(), we place the burden of checking whether the host
enabled remote wakeup in the UDC driver. For usb_func_wakeup(), you
place the burden of checking whether the host enabled function remote
wakeup in the composite layer. If we have usb_gadget_func_wakeup(), then
you may need to clarify how to handle that.
> + *
> + * Returns zero on success, else negative errno.
> + */
> +int usb_func_wakeup(struct usb_function *func)
> +{
> + struct usb_gadget *gadget = func->config->cdev->gadget;
> + int id;
> +
> + if (!func->func_wakeup_armed) {
> + ERROR(func->config->cdev, "not armed for func remote wakeup\n");
> + return -EINVAL;
> + }
> +
> + if (!gadget->ops->func_wakeup)
> + return -EOPNOTSUPP;
Maybe this check should go first.
> +
> + for (id = 0; id < MAX_CONFIG_INTERFACES; id++)
> + if (func->config->interface[id] == func)
> + break;
> +
> + if (id == MAX_CONFIG_INTERFACES) {
> + ERROR(func->config->cdev, "Invalid function\n");
> + return -EINVAL;
> + }
> +
> + return gadget->ops->func_wakeup(gadget, id);
> +}
> +EXPORT_SYMBOL_GPL(usb_func_wakeup);
> +
> static u8 encode_bMaxPower(enum usb_device_speed speed,
> struct usb_configuration *c)
> {
> diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
> index d949e91..a2448e9 100644
> --- a/include/linux/usb/composite.h
> +++ b/include/linux/usb/composite.h
> @@ -150,6 +150,9 @@ struct usb_os_desc_table {
> * GetStatus() request when the recipient is Interface.
> * @func_suspend: callback to be called when
> * SetFeature(FUNCTION_SUSPEND) is reseived
> + * @func_suspended: Indicates whether the function is in function suspend state.
> + * @func_wakeup_armed: Indicates whether the function is armed by the host for
> + * wakeup signaling.
> *
> * A single USB function uses one or more interfaces, and should in most
> * cases support operation at both full and high speeds. Each function is
> @@ -220,6 +223,8 @@ struct usb_function {
> int (*get_status)(struct usb_function *);
> int (*func_suspend)(struct usb_function *,
> u8 suspend_opt);
> + bool func_suspended;
> + bool func_wakeup_armed;
> /* private: */
> /* internals */
> struct list_head list;
> @@ -241,6 +246,7 @@ int config_ep_by_speed_and_alt(struct usb_gadget *g, struct usb_function *f,
>
> int config_ep_by_speed(struct usb_gadget *g, struct usb_function *f,
> struct usb_ep *_ep);
> +int usb_func_wakeup(struct usb_function *func);
>
> #define MAX_CONFIG_INTERFACES 16 /* arbitrary; max 255 */
>
> diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
> index 1d79612..75bda078 100644
> --- a/include/linux/usb/gadget.h
> +++ b/include/linux/usb/gadget.h
> @@ -310,6 +310,7 @@ struct usb_udc;
> struct usb_gadget_ops {
> int (*get_frame)(struct usb_gadget *);
> int (*wakeup)(struct usb_gadget *);
> + int (*func_wakeup)(struct usb_gadget *gadget, int intf_id);
> int (*set_remote_wakeup)(struct usb_gadget *, int set);
> int (*set_selfpowered) (struct usb_gadget *, int is_selfpowered);
> int (*vbus_session) (struct usb_gadget *, int is_active);
> --
> 2.7.4
>
Thanks,
Thinh
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