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Commit a8eda9fa authored by Karoly Pados's avatar Karoly Pados Committed by Johan Hovold
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USB: serial: ftdi_sio: fix GPIO not working in autosuspend 



There is a bug in the current GPIO code for ftdi_sio: it failed to take USB
autosuspend into account. If the device is in autosuspend, calls to
usb_control_msg() fail with -EHOSTUNREACH. Because the standard value for
autosuspend timeout is usually 2-5 seconds, this made it almost impossible
to use the GPIOs on machines that have USB autosuspend enabled. This patch
fixes the issue by acquiring a PM lock on the device for the duration of
the USB transfers. Tested on an FT231X device.

Signed-off-by: default avatarKaroly Pados <pados@pados.hu>
[ johan: simplify code somewhat ]
Fixes: ba93cc7d ("USB: serial: ftdi_sio: implement GPIO support for FT-X devices")
Cc: stable <stable@vger.kernel.org>	# 4.20
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
parent b81c2c33

drivers/usb/serial/ftdi_sio.c

+14 −1
Original line number Diff line number Diff line
@@ -1783,6 +1783,10 @@ static int ftdi_set_bitmode(struct usb_serial_port *port, u8 mode) 
	int result;

	u16 val;



	result = usb_autopm_get_interface(serial->interface);

	if (result)

		return result;



	val = (mode << 8) | (priv->gpio_output << 4) | priv->gpio_value;

	result = usb_control_msg(serial->dev,

				 usb_sndctrlpipe(serial->dev, 0),
@@ -1795,6 +1799,8 @@ static int ftdi_set_bitmode(struct usb_serial_port *port, u8 mode) 
			val, result);

	}



	usb_autopm_put_interface(serial->interface);



	return result;

}
@@ -1846,9 +1852,15 @@ static int ftdi_read_cbus_pins(struct usb_serial_port *port) 
	unsigned char *buf;

	int result;



	result = usb_autopm_get_interface(serial->interface);

	if (result)

		return result;



	buf = kmalloc(1, GFP_KERNEL);

	if (!buf)

	if (!buf) {

		usb_autopm_put_interface(serial->interface);

		return -ENOMEM;

	}



	result = usb_control_msg(serial->dev,

				 usb_rcvctrlpipe(serial->dev, 0),
@@ -1863,6 +1875,7 @@ static int ftdi_read_cbus_pins(struct usb_serial_port *port) 
	}



	kfree(buf);

	usb_autopm_put_interface(serial->interface);



	return result;

}