Hello.
On 7/14/2015 1:37 AM, Tilman Schmidt wrote:
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 <til...@imap.cc>
---
drivers/isdn/gigaset/ser-gigaset.c | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/drivers/isdn/gigaset/ser-gigaset.c
b/drivers/isdn/gigaset/ser-gigaset.c
index 8c91fd5..3ac9c41 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);
init_completion(&cs->hw.ser->dead_cmp);
-
Unrelated change?
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;
The general kernel coding style is to surround operators with spaces.
[...]
MBR, Sergei
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