patch "USB: serial: ftdi_sio: fix GPIO not working in autosuspend" added to usb-linus

This is a note to let you know that I've just added the patch titled

USB: serial: ftdi_sio: fix GPIO not working in autosuspend

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From a8eda9fa1bd84065b75bfa81bf675a7af9055478 Mon Sep 17 00:00:00 2001
From: Karoly Pados <[email protected]>
Date: Mon, 14 Jan 2019 13:30:03 +0100
Subject: 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.

---
 drivers/usb/serial/ftdi_sio.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

index 1ab2a6191013..77ef4c481f3c 100644
@@ -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;
 }

2.20.1