Commit aba3a8d0 authored by Fabrice Gasnier's avatar Fabrice Gasnier Committed by Felipe Balbi
Browse files

usb: gadget: u_serial: add suspend resume callbacks 



Add suspend resume callbacks to handle the case seen when the bus is
suspended by the HOST, and the device opens the port (cat /dev/ttyGS0).

Gadget controller (like DWC2) doesn't accept usb requests to be queued in
this case (when in L2 state), from the gs_open() call. Error log is printed
- configfs-gadget gadget: acm ttyGS0 can't notify serial state, -11
If the HOST resumes (opens) the bus, the port still isn't functional.

Use suspend/resume callbacks to monitor the gadget suspended state by using
'suspended' flag. In case the port gets opened (cat /dev/ttyGS0), the I/O
stream will be delayed until the bus gets resumed by the HOST.

Signed-off-by: default avatarFabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: default avatarFelipe Balbi <balbi@kernel.org>
parent 8c935dea

drivers/usb/gadget/function/u_serial.c

+49 −8
Original line number Diff line number Diff line
@@ -120,6 +120,8 @@ struct gs_port { 
	wait_queue_head_t	drain_wait;	/* wait while writes drain */

	bool                    write_busy;

	wait_queue_head_t	close_wait;

	bool			suspended;	/* port suspended */

	bool			start_delayed;	/* delay start when suspended */



	/* REVISIT this state ... */

	struct usb_cdc_line_coding port_line_coding;	/* 8-N-1 etc */
@@ -630,6 +632,8 @@ static int gs_open(struct tty_struct *tty, struct file *file) 


	/* if connected, start the I/O stream */

	if (port->port_usb) {

		/* if port is suspended, wait resume to start I/0 stream */

		if (!port->suspended) {

			struct gserial	*gser = port->port_usb;



			pr_debug("gs_open: start ttyGS%d\n", port->port_num);
@@ -637,6 +641,10 @@ static int gs_open(struct tty_struct *tty, struct file *file) 


			if (gser->connect)

				gser->connect(gser);

		} else {

			pr_debug("delay start of ttyGS%d\n", port->port_num);

			port->start_delayed = true;

		}

	}



	pr_debug("gs_open: ttyGS%d (%p,%p)\n", port->port_num, tty, file);
@@ -680,7 +688,7 @@ static void gs_close(struct tty_struct *tty, struct file *file) 
	pr_debug("gs_close: ttyGS%d (%p,%p) ...\n", port->port_num, tty, file);



	gser = port->port_usb;

	if (gser && gser->disconnect)

	if (gser && !port->suspended && gser->disconnect)

		gser->disconnect(gser);



	/* wait for circular write buffer to drain, disconnect, or at
@@ -708,6 +716,7 @@ static void gs_close(struct tty_struct *tty, struct file *file) 
	else

		kfifo_reset(&port->port_write_buf);



	port->start_delayed = false;

	port->port.count = 0;

	port->port.tty = NULL;
@@ -1403,6 +1412,38 @@ void gserial_disconnect(struct gserial *gser) 
}

EXPORT_SYMBOL_GPL(gserial_disconnect);



void gserial_suspend(struct gserial *gser)

{

	struct gs_port	*port = gser->ioport;

	unsigned long	flags;



	spin_lock_irqsave(&port->port_lock, flags);

	port->suspended = true;

	spin_unlock_irqrestore(&port->port_lock, flags);

}

EXPORT_SYMBOL_GPL(gserial_suspend);



void gserial_resume(struct gserial *gser)

{

	struct gs_port *port = gser->ioport;

	unsigned long	flags;



	spin_lock_irqsave(&port->port_lock, flags);

	port->suspended = false;

	if (!port->start_delayed) {

		spin_unlock_irqrestore(&port->port_lock, flags);

		return;

	}



	pr_debug("delayed start ttyGS%d\n", port->port_num);

	gs_start_io(port);

	if (gser->connect)

		gser->connect(gser);

	port->start_delayed = false;

	spin_unlock_irqrestore(&port->port_lock, flags);

}

EXPORT_SYMBOL_GPL(gserial_resume);



static int userial_init(void)

{

	unsigned			i;

drivers/usb/gadget/function/u_serial.h

+2 −0
Original line number Diff line number Diff line
@@ -68,6 +68,8 @@ ssize_t gserial_get_console(unsigned char port_num, char *page); 
/* connect/disconnect is handled by individual functions */

int gserial_connect(struct gserial *, u8 port_num);

void gserial_disconnect(struct gserial *);

void gserial_suspend(struct gserial *p);

void gserial_resume(struct gserial *p);



/* functions are bound to configurations by a config or gadget driver */

int gser_bind_config(struct usb_configuration *c, u8 port_num);