[PATCH V4 1/3] USB: serial: f81232: clear overrun flag

Ji-Ze Hong (Peter Hong)
2019-04-02T05:26:44Z

The F81232 will report data and LSR with bulk like following format:
bulk-in data: [LSR(1Byte)+DATA(1Byte)][LSR(1Byte)+DATA(1Byte)]...

LSR will auto clear frame/parity/break error flag when reading by H/W,
but overrrun will only cleared when reading LSR. So this patch add a
worker to read LSR when overrun and flush the worker on close() &
suspend().

Cc: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
---
v4:
1: Add serial->suspending check in f81232_lsr_worker() to avoid
re-trigger
2: Add port_priv-lsr_work_resched to re-trigger LSR worker

v3:
1: Add flush_work(&port_priv->lsr_work) in f81232_suspend().

v2:
1: Add flush_work(&port_priv->lsr_work) in f81232_close().

drivers/usb/serial/f81232.c | 57 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)

diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
index 0dcdcb4b2cde..9345f13274e9 100644
--- a/drivers/usb/serial/f81232.c
+++ b/drivers/usb/serial/f81232.c
@@ -41,12 +41,15 @@ MODULE_DEVICE_TABLE(usb, id_table);
#define FIFO_CONTROL_REGISTER (0x02 + SERIAL_BASE_ADDRESS)
#define LINE_CONTROL_REGISTER (0x03 + SERIAL_BASE_ADDRESS)
#define MODEM_CONTROL_REGISTER (0x04 + SERIAL_BASE_ADDRESS)
+#define LINE_STATUS_REGISTER (0x05 + SERIAL_BASE_ADDRESS)
#define MODEM_STATUS_REGISTER (0x06 + SERIAL_BASE_ADDRESS)

struct f81232_private {
struct mutex lock;
u8 modem_control;
u8 modem_status;
+ bool lsr_work_resched;
+ struct work_struct lsr_work;
struct work_struct interrupt_work;
struct usb_serial_port *port;
};
@@ -282,6 +285,7 @@ static void f81232_read_int_callback(struct urb *urb)
static void f81232_process_read_urb(struct urb *urb)
{
struct usb_serial_port *port = urb->context;
+ struct f81232_private *priv = usb_get_serial_port_data(port);
unsigned char *data = urb->transfer_buffer;
char tty_flag;
unsigned int i;
@@ -315,6 +319,7 @@ static void f81232_process_read_urb(struct urb *urb)

if (lsr & UART_LSR_OE) {
port->icount.overrun++;
+ schedule_work(&priv->lsr_work);
tty_insert_flip_char(&port->port, 0,
TTY_OVERRUN);
}
@@ -556,9 +561,12 @@ static int f81232_open(struct tty_struct *tty, struct usb_serial_port *port)

static void f81232_close(struct usb_serial_port *port)
{
+ struct f81232_private *port_priv = usb_get_serial_port_data(port);
+
f81232_port_disable(port);
usb_serial_generic_close(port);
usb_kill_urb(port->interrupt_in_urb);
+ flush_work(&port_priv->lsr_work);
}

static void f81232_dtr_rts(struct usb_serial_port *port, int on)
@@ -603,6 +611,28 @@ static void f81232_interrupt_work(struct work_struct *work)
f81232_read_msr(priv->port);
}

+static void f81232_lsr_worker(struct work_struct *work)
+{
+ struct f81232_private *priv;
+ struct usb_serial_port *port;
+ struct usb_serial *serial;
+ int status;
+ u8 tmp;
+
+ priv = container_of(work, struct f81232_private, lsr_work);
+ port = priv->port;
+ serial = port->serial;
+
+ if (serial->suspending) {
+ priv->lsr_work_resched = true;
+ return;
+ }
+
+ status = f81232_get_register(port, LINE_STATUS_REGISTER, &tmp);
+ if (status)
+ dev_warn(&port->dev, "read LSR failed: %d\n", status);
+}
+
static int f81232_port_probe(struct usb_serial_port *port)
{
struct f81232_private *priv;
@@ -613,6 +643,7 @@ static int f81232_port_probe(struct usb_serial_port *port)

mutex_init(&priv->lock);
INIT_WORK(&priv->interrupt_work, f81232_interrupt_work);
+ INIT_WORK(&priv->lsr_work, f81232_lsr_worker);

usb_set_serial_port_data(port, priv);

@@ -632,6 +663,30 @@ static int f81232_port_remove(struct usb_serial_port *port)
return 0;
}

+static int f81232_suspend(struct usb_serial *serial, pm_message_t message)
+{
+ struct f81232_private *port_priv;
+
+ port_priv = usb_get_serial_port_data(serial->port[0]);
+ flush_work(&port_priv->lsr_work);
+
+ return 0;
+}
+
+static int f81232_resume(struct usb_serial *serial)
+{
+ struct f81232_private *port_priv;
+
+ port_priv = usb_get_serial_port_data(serial->port[0]);
+
+ if (port_priv->lsr_work_resched) {
+ port_priv->lsr_work_resched = false;
+ schedule_work(&port_priv->lsr_work);
+ }
+
+ return usb_serial_generic_resume(serial);
+}
+
static struct usb_serial_driver f81232_device = {
.driver = {
.owner = THIS_MODULE,
@@ -655,6 +710,8 @@ static struct usb_serial_driver f81232_device = {
.read_int_callback = f81232_read_int_callback,
.port_probe = f81232_port_probe,
.port_remove = f81232_port_remove,
+ .suspend = f81232_suspend,
+ .resume = f81232_resume,
};

static struct usb_serial_driver * const serial_drivers[] = {
--
2.7.4