diff options
authorTilman Schmidt <tilman@imap.cc>2015-07-14 00:37:13 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-01 12:07:36 +0200
commitc6419a861e56cf6c6446bf0e8f9c75557c2a3a02 (patch)
parent8d228c93f31c90894fa86c597beb42b67c5ac978 (diff)
isdn/gigaset: reset tty->receive_room when attaching ser_gigaset
[ Upstream commit fd98e9419d8d622a4de91f76b306af6aa627aa9c ] Commit 79901317ce80 ("n_tty: Don't flush buffer when closing ldisc"), first merged in kernel release 3.10, caused the following regression in the Gigaset M101 driver: Before that commit, when closing the N_TTY line discipline in preparation to switching to N_GIGASET_M101, receive_room would be reset to a non-zero value by the call to n_tty_flush_buffer() in n_tty's close method. With the removal of that call, receive_room might be left at zero, blocking data reception on the serial line. The present patch fixes that regression by setting receive_room to an appropriate value in the ldisc open method. Fixes: 79901317ce80 ("n_tty: Don't flush buffer when closing ldisc") Signed-off-by: Tilman Schmidt <tilman@imap.cc> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/isdn/gigaset/ser-gigaset.c b/drivers/isdn/gigaset/ser-gigaset.c
index 8c91fd5eb6fd..3ac9c4194814 100644
--- a/drivers/isdn/gigaset/ser-gigaset.c
+++ b/drivers/isdn/gigaset/ser-gigaset.c
@@ -524,9 +524,18 @@ gigaset_tty_open(struct tty_struct *tty)
cs->hw.ser->tty = tty;
atomic_set(&cs->hw.ser->refcnt, 1);
tty->disc_data = cs;
+ /* Set the amount of data we're willing to receive per call
+ * from the hardware driver to half of the input buffer size
+ * to leave some reserve.
+ * Note: We don't do flow control towards the hardware driver.
+ * If more data is received than will fit into the input buffer,
+ * it will be dropped and an error will be logged. This should
+ * never happen as the device is slow and the buffer size ample.
+ */
+ tty->receive_room = RBUFSIZE/2;
/* OK.. Initialization of the datastructures and the HW is done.. Now
* startup system and notify the LL that we are ready to run