Re: [PATCH v3 1/5] usb: gadget: Properly configure the device for remote wakeup

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

Hi Elson,

On Mon, Feb 06, 2023, Elson Roy Serrao wrote:
> The wakeup bit in the bmAttributes field indicates whether the device
> is configured for remote wakeup. But this field should be allowed to
> set only if the UDC supports such wakeup mechanism. So configure this
> field based on UDC capability. Also inform the UDC whether the device
> is configured for remote wakeup by implementing a gadget op.
> 
> Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
> ---
>  drivers/usb/gadget/composite.c | 24 +++++++++++++++++++++++-
>  drivers/usb/gadget/udc/core.c  | 27 +++++++++++++++++++++++++++
>  drivers/usb/gadget/udc/trace.h |  5 +++++
>  include/linux/usb/gadget.h     |  8 ++++++++
>  4 files changed, 63 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> index fa7dd6c..e459fb0 100644
> --- a/drivers/usb/gadget/composite.c
> +++ b/drivers/usb/gadget/composite.c
> @@ -513,6 +513,19 @@ static u8 encode_bMaxPower(enum usb_device_speed speed,
>  		return min(val, 900U) / 8;
>  }
>  
> +static void check_remote_wakeup_config(struct usb_gadget *gadget,
> +				       struct usb_configuration *c)
> +{
> +	if (USB_CONFIG_ATT_WAKEUP & c->bmAttributes) {
> +		/* Reset the rw bit if gadget is not capable of it */
> +		if (!gadget->rw_capable) {

Probably it's better to make sure we don't break the configuration for
other UDCs until this is implemented in their drivers. Let's add another
condition:

	if (!gadget->rw_capable && gadget->ops->set_remotewakeup) {
		...
	}

> +			INFO(c->cdev, "Clearing rw bit for config c.%d\n",
> +			     c->bConfigurationValue);

Perhaps a warning is better since we're overwriting the user's
configuration.

> +			c->bmAttributes &= ~USB_CONFIG_ATT_WAKEUP;
> +		}
> +	}
> +}
> +
>  static int config_buf(struct usb_configuration *config,
>  		enum usb_device_speed speed, void *buf, u8 type)
>  {
> @@ -620,8 +633,12 @@ static int config_desc(struct usb_composite_dev *cdev, unsigned w_value)
>  				continue;
>  		}
>  
> -		if (w_value == 0)
> +		if (w_value == 0) {
> +			/* Correctly configure the bmAttributes wakeup bit */
> +			check_remote_wakeup_config(gadget, c);

Checking here is too late. We should check in configfs_composite_bind().

> +
>  			return config_buf(c, speed, cdev->req->buf, type);
> +		}
>  		w_value--;
>  	}
>  	return -EINVAL;
> @@ -1000,6 +1017,11 @@ static int set_config(struct usb_composite_dev *cdev,
>  	else
>  		usb_gadget_clear_selfpowered(gadget);
>  
> +	if (USB_CONFIG_ATT_WAKEUP & c->bmAttributes)
> +		usb_gadget_set_remotewakeup(gadget, 1);
> +	else
> +		usb_gadget_set_remotewakeup(gadget, 0);
> +
>  	usb_gadget_vbus_draw(gadget, power);
>  	if (result >= 0 && cdev->delayed_status)
>  		result = USB_GADGET_DELAYED_STATUS;
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 23b0629..5874d4f 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -514,6 +514,33 @@ int usb_gadget_wakeup(struct usb_gadget *gadget)
>  EXPORT_SYMBOL_GPL(usb_gadget_wakeup);
>  
>  /**
> + * usb_gadget_set_remotewakeup - configures the device remote wakeup feature.
> + * @gadget:the device being configured for remote wakeup
> + * @set:value to be configured.
> + *
> + * set to one to enable remote wakeup feature and zero to disable it.
> + *
> + * returns zero on success, else negative errno.
> + */
> +int usb_gadget_set_remotewakeup(struct usb_gadget *gadget, int set)
> +{
> +	int ret = 0;
> +
> +	if (!gadget->ops->set_remotewakeup) {
> +		ret = -EOPNOTSUPP;
> +		goto out;
> +	}
> +
> +	ret = gadget->ops->set_remotewakeup(gadget, set);
> +
> +out:
> +	trace_usb_gadget_set_remotewakeup(gadget, ret);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(usb_gadget_set_remotewakeup);
> +
> +/**
>   * usb_gadget_set_selfpowered - sets the device selfpowered feature.
>   * @gadget:the device being declared as self-powered
>   *
> diff --git a/drivers/usb/gadget/udc/trace.h b/drivers/usb/gadget/udc/trace.h
> index abdbcb1..a3314ce 100644
> --- a/drivers/usb/gadget/udc/trace.h
> +++ b/drivers/usb/gadget/udc/trace.h
> @@ -91,6 +91,11 @@ DEFINE_EVENT(udc_log_gadget, usb_gadget_wakeup,
>  	TP_ARGS(g, ret)
>  );
>  
> +DEFINE_EVENT(udc_log_gadget, usb_gadget_set_remotewakeup,
> +	TP_PROTO(struct usb_gadget *g, int ret),
> +	TP_ARGS(g, ret)
> +);
> +
>  DEFINE_EVENT(udc_log_gadget, usb_gadget_set_selfpowered,
>  	TP_PROTO(struct usb_gadget *g, int ret),
>  	TP_ARGS(g, ret)
> diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
> index dc3092c..05d1449 100644
> --- a/include/linux/usb/gadget.h
> +++ b/include/linux/usb/gadget.h
> @@ -309,6 +309,7 @@ struct usb_udc;
>  struct usb_gadget_ops {
>  	int	(*get_frame)(struct usb_gadget *);
>  	int	(*wakeup)(struct usb_gadget *);
> +	int	(*set_remotewakeup)(struct usb_gadget *, int set);

minor nit: can we change this name to set_remote_wakeup. It's a bit
easier to read IMO.

>  	int	(*set_selfpowered) (struct usb_gadget *, int is_selfpowered);
>  	int	(*vbus_session) (struct usb_gadget *, int is_active);
>  	int	(*vbus_draw) (struct usb_gadget *, unsigned mA);
> @@ -383,6 +384,8 @@ struct usb_gadget_ops {
>   * @connected: True if gadget is connected.
>   * @lpm_capable: If the gadget max_speed is FULL or HIGH, this flag
>   *	indicates that it supports LPM as per the LPM ECN & errata.
> + * @rw_capable: True if gadget is capable of sending remote wakeup.
> + * @rw_armed: True if gadget is armed by the host for remote wakeup.
>   * @irq: the interrupt number for device controller.
>   * @id_number: a unique ID number for ensuring that gadget names are distinct
>   *
> @@ -444,6 +447,8 @@ struct usb_gadget {
>  	unsigned			deactivated:1;
>  	unsigned			connected:1;
>  	unsigned			lpm_capable:1;
> +	unsigned			rw_capable:1;
> +	unsigned			rw_armed:1;
>  	int				irq;
>  	int				id_number;
>  };
> @@ -600,6 +605,7 @@ static inline int gadget_is_otg(struct usb_gadget *g)
>  #if IS_ENABLED(CONFIG_USB_GADGET)
>  int usb_gadget_frame_number(struct usb_gadget *gadget);
>  int usb_gadget_wakeup(struct usb_gadget *gadget);
> +int usb_gadget_set_remotewakeup(struct usb_gadget *gadget, int set);
>  int usb_gadget_set_selfpowered(struct usb_gadget *gadget);
>  int usb_gadget_clear_selfpowered(struct usb_gadget *gadget);
>  int usb_gadget_vbus_connect(struct usb_gadget *gadget);
> @@ -615,6 +621,8 @@ static inline int usb_gadget_frame_number(struct usb_gadget *gadget)
>  { return 0; }
>  static inline int usb_gadget_wakeup(struct usb_gadget *gadget)
>  { return 0; }
> +static inline int usb_gadget_set_remotewakeup(struct usb_gadget *gadget, int set)
> +{ return 0; }
>  static inline int usb_gadget_set_selfpowered(struct usb_gadget *gadget)
>  { return 0; }
>  static inline int usb_gadget_clear_selfpowered(struct usb_gadget *gadget)
> -- 
> 2.7.4
> 

Thanks,
Thinh