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usb: gadget: u_serial: add suspend resume callbacks

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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: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
This commit is contained in:
Fabrice Gasnier 2020-04-23 13:55:54 +02:00 committed by Felipe Balbi
parent 8c935deace
commit aba3a8d01d
2 changed files with 49 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
drivers/usb/gadget/function/u_serial.c
View File

@ -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 */
@ -630,13 +632,19 @@ static int gs_open(struct tty_struct *tty, struct file *file)
/* if connected, start the I/O stream */
if (port->port_usb) {
struct gserial *gser = 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);
gs_start_io(port);
pr_debug("gs_open: start ttyGS%d\n", port->port_num);
gs_start_io(port);
if (gser->connect)
gser->connect(gser);
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 @@ raced_with_open:
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 @@ raced_with_open:
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;

2
drivers/usb/gadget/function/u_serial.h
View File

@ -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);