linux-kernel - [PATCH v2] tty: n_gsm: delete SABM command frame as requester

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Message-Id: <1625138840-22974-1-git-send-email-zhenguo6858@gmail.com>
Date:   Thu,  1 Jul 2021 19:27:20 +0800
From:   Zhenguo Zhao <zhenguo6858@...il.com>
To:     zhenguo6858@...il.com, gregkh@...uxfoundation.org,
        jirislaby@...nel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH v2] tty: n_gsm: delete SABM command frame as requester

From: Zhenguo Zhao <Zhenguo.Zhao1@...soc.com>

as initiator,it need to send SABM command ,as requester,there is
no need to send the SABM control frame,it will cause redundant data.

Signed-off-by: Zhenguo Zhao <Zhenguo.Zhao1@...soc.com>
---
 drivers/tty/n_gsm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 5fea02c..41a6501 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2997,6 +2997,7 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp)
 {
 	struct gsm_dlci *dlci = tty->driver_data;
 	struct tty_port *port = &dlci->port;
+	struct gsm_mux *gsm = dlci->gsm;
 
 	port->count++;
 	tty_port_tty_set(port, tty);
@@ -3005,8 +3006,9 @@ static int gsmtty_open(struct tty_struct *tty, struct file *filp)
 	/* We could in theory open and close before we wait - eg if we get
 	   a DM straight back. This is ok as that will have caused a hangup */
 	tty_port_set_initialized(port, 1);
-	/* Start sending off SABM messages */
-	gsm_dlci_begin_open(dlci);
+	/* Start sending off SABM messages for initiator */
+	if (gsm->initiator)
+		gsm_dlci_begin_open(dlci);
 	/* And wait for virtual carrier */
 	return tty_port_block_til_ready(port, tty, filp);
 }
-- 
1.9.1