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isdn/gigaset: reset tty->receive_room when attaching ser_gigaset 

Commit 79901317ce ("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: 79901317ce ("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>
This commit is contained in:
Tilman Schmidt 2015-07-14 00:37:13 +02:00 committed by David S. Miller
parent 052cbda41f
commit fd98e9419d
1 changed files with 10 additions and 1 deletions
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11
drivers/isdn/gigaset/ser-gigaset.c
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@ -524,9 +524,18 @@ gigaset_tty_open(struct tty_struct *tty)
cs->hw.ser->tty = tty;
atomic_set(&cs->hw.ser->refcnt, 1);
init_completion(&cs->hw.ser->dead_cmp);
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
*/