n_gsm: Send CLD command on exit

A DISC on DLCI 0 should close down the mux but Michael Lauer reports this
is not the case for some modems. Send a CLD as well.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Tested-by: Michael Lauer
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index ed429082304d..8d7766bfef87 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2003,6 +2003,7 @@ void gsm_cleanup_mux(struct gsm_mux *gsm)
         int i;
         struct gsm_dlci *dlci = gsm->dlci[0];
         struct gsm_msg *txq;
+        struct gsm_control *gc;
 
         gsm->dead = 1;
 
@@ -2016,6 +2017,13 @@ void gsm_cleanup_mux(struct gsm_mux *gsm)
         spin_unlock(&gsm_mux_lock);
         WARN_ON(i == MAX_MUX);
 
+        /* In theory disconnecting DLCI 0 is sufficient but for some
+           modems this is apparently not the case. */
+        if (dlci) {
+                gc = gsm_control_send(gsm, CMD_CLD, NULL, 0);
+                if (gc)
+                        gsm_control_wait(gsm, gc);
+        }
         del_timer_sync(&gsm->t2_timer);
         /* Now we are sure T2 has stopped */
         if (dlci) {