[PATCH 3.16.y-ckt 041/180] usb: serial: silence all non-critical read errors

[Luis Henriques]

3.16.7-ckt11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeremiah Mahler <jmmahler at gmail.com>

commit aa8e22128b40590b291cd13512098bf258a7e6c5 upstream.

If a USB serial device is unplugged while there is an active program
using the device it may spam the logs with -EPROTO (71) messages as it
attempts to retry.

Most serial usb drivers (metro-usb, pl2303, mos7840, ...) only output
these messages for debugging.  The generic driver treats these as
errors.

Change the default output for the generic serial driver from error to
debug to silence these non-critical errors.

Signed-off-by: Jeremiah Mahler <jmmahler at gmail.com>
Signed-off-by: Johan Hovold <johan at kernel.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/usb/serial/generic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 904ab353ecf2..c44b911937e8 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -374,7 +374,7 @@ void usb_serial_generic_read_bulk_callback(struct urb *urb)
 							__func__, urb->status);
 		return;
 	default:
-		dev_err(&port->dev, "%s - nonzero urb status: %d\n",
+		dev_dbg(&port->dev, "%s - nonzero urb status: %d\n",
 							__func__, urb->status);
 		goto resubmit;
 	}