staging: gpib: Return -EINTR on device clear

commit aaf2af1ed147ef49be65afb541a67255e9f60d15 upstream.

When the ATN (Attention) line is asserted during a read we get a
NIUSB_ATN_STATE_ERROR during a read. For the controller to send a
device clear it asserts ATN. Normally this is an error but in the case
of a device clear it should be regarded as an interrupt.

Return -EINTR when the Device Clear Active State (DCAS) is entered
else signal an error with dev_dbg with status instead of just dev_err.

Signed-off-by: Dave Penkler <dpenkler@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
index 73ea72f34c0a33a2276aaf95a939ba52fdf84282..4e9a654bf51f4fc9fcaf917bb2fdef48bb25e8ca 100644 (file)
--- a/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
+++ b/drivers/staging/gpib/ni_usb/ni_usb_gpib.c
@@ -694,8 +694,12 @@ static int ni_usb_read(struct gpib_board *board, u8 *buffer, size_t length,
                 */
                break;
        case NIUSB_ATN_STATE_ERROR:
-               retval = -EIO;
-               dev_err(&usb_dev->dev, "read when ATN set\n");
+               if (status.ibsta & DCAS) {
+                       retval = -EINTR;
+               } else {
+                       retval = -EIO;
+                       dev_dbg(&usb_dev->dev, "read when ATN set stat: 0x%06x\n", status.ibsta);
+               }
                break;
        case NIUSB_ADDRESSING_ERROR:
                retval = -EIO;