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@xxxxxx>
---
drivers/usb/gadget/function/u_serial.c | 57 +++++++++++++++++++++++++++++-----
drivers/usb/gadget/function/u_serial.h | 2 ++
2 files changed, 51 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 8167d37..3cfc6e2 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -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;
-
- pr_debug("gs_open: start ttyGS%d\n", port->port_num);
- gs_start_io(port);
-
- if (gser->connect)
- gser->connect(gser);
+ /* 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);
+
+ 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;
diff --git a/drivers/usb/gadget/function/u_serial.h b/drivers/usb/gadget/function/u_serial.h
index e5b08ab..009a959 100644
--- a/drivers/usb/gadget/function/u_serial.h
+++ b/drivers/usb/gadget/function/u_serial.h
@@ -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);
--
2.7.4
