[PATCH v2 2/2] n_gsm: fix UIH control byte : P bit should be 0

From: Eric BÃnard
Date: Wed Mar 09 2011 - 13:34:06 EST


* the GSM 07.10 specification says in 5.4.3.1 that
'both stations shall set the P bit to 0'
thanks to Alan Cox for finding this explanation in the spec

* without this fix, on Telit & Sim.com modems, opening a new DLC
randomly fails. Not setting PF bit of the control byte gives a
reliable behaviour on these modems.

Signed-off-by: Eric BÃnard <eric@xxxxxxxxxx>
---
v2 : updated patch and comment following Alan's review

drivers/tty/n_gsm.c | 3 +--
1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index aa2e5d3..6613918 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1250,8 +1250,7 @@ static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,

static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
{
- struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1,
- gsm->ftype|PF);
+ struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1, gsm->ftype);
if (msg == NULL)
return;
msg->data[0] = (ctrl->cmd << 1) | 2 | EA; /* command */
--
1.7.4

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