[1/5] USB: serial: f81232: clear overrun flag

[1/5] USB: serial: f81232: clear overrun flag

[Ji-Ze Hong (Peter Hong)]

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 OE.

Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
---
 drivers/usb/serial/f81232.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
index 96036f87b1de..46836041c50e 100644
--- a/drivers/usb/serial/f81232.c
+++ b/drivers/usb/serial/f81232.c
@@ -41,12 +41,14 @@ 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;
+	struct work_struct lsr_work;
 	struct work_struct interrupt_work;
 	struct usb_serial_port *port;
 };
@@ -282,6 +284,7 @@ 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 +318,7 @@ 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);
 			}
@@ -623,6 +627,21 @@ 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;
+	int status;
+	u8 tmp;
+
+	priv = container_of(work, struct f81232_private, lsr_work);
+	port = priv->port;
+
+	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;
@@ -633,6 +652,7 @@ 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);
 

[1/5] USB: serial: f81232: clear overrun flag

[Oliver Neukum]

Am Montag, den 22.01.2018, 15:58 +0800 schrieb  Ji-Ze Hong (Peter Hong)
:
> 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 OE.
> 
> Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
[..] 
> +static void f81232_lsr_worker(struct work_struct *work)
> +{
> +	struct f81232_private *priv;
> +	struct usb_serial_port *port;
> +	int status;
> +	u8 tmp;
> +
> +	priv = container_of(work, struct f81232_private, lsr_work);
> +	port = priv->port;
> +
> +	status = f81232_get_register(port, LINE_STATUS_REGISTER, &tmp);
> +	if (status)
> +		dev_warn(&port->dev, "read LSR failed: %d\n", status);
> +}

Hi,

I am afraid this is incomplete. You are scheduling a work that does IO.
Hence you must cancel that work when the driver is unbound from the
interface. You must also not do IO like this while the system is suspending.

	Regards
		Oliver
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[1/5] USB: serial: f81232: clear overrun flag

[Ji-Ze Hong (Peter Hong)]

Hi Oliver,

Oliver Neukum 於 2018/1/22 下午 06:06 寫道:
>> +static void f81232_lsr_worker(struct work_struct *work)
>> +{
>> +	struct f81232_private *priv;
>> +	struct usb_serial_port *port;
>> +	int status;
>> +	u8 tmp;
>> +
>> +	priv = container_of(work, struct f81232_private, lsr_work);
>> +	port = priv->port;
>> +
>> +	status = f81232_get_register(port, LINE_STATUS_REGISTER, &tmp);
>> +	if (status)
>> +		dev_warn(&port->dev, "read LSR failed: %d\n", status);
>> +}
> 
> Hi,
> 
> I am afraid this is incomplete. You are scheduling a work that does IO.
> Hence you must cancel that work when the driver is unbound from the
> interface. You must also not do IO like this while the system is suspending.

We'll add cancel worker operation on close() and suspend() to prevent
from I/O operations in wrong time with next patch version.

Thanks