From aba3a8d01d623a5efef48ab8e78752d58d4c90c3 Mon Sep 17 00:00:00 2001 From: Fabrice Gasnier Date: Thu, 23 Apr 2020 13:55:54 +0200 Subject: 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: Fabrice Gasnier Signed-off-by: Felipe Balbi --- drivers/usb/gadget/function/u_serial.c | 57 +++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 8 deletions(-) (limited to 'drivers/usb/gadget/function/u_serial.c') diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index 8167d379e115..3cfc6e2eba71 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 @@ 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; -- cgit v1.2.3-59-g8ed1b