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tty: n_gsm: fix wrong tty control line for flow control

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commit c19d93542a6081577e6da9bf5e887979c72e80c1 upstream.

tty flow control is handled via gsmtty_throttle() and gsmtty_unthrottle().
Both functions propagate the outgoing hardware flow control state to the
remote side via MSC (modem status command) frames. The local state is taken
from the RTS (ready to send) flag of the tty. However, RTS gets mapped to
DTR (data terminal ready), which is wrong.
This patch corrects this by mapping RTS to RTS.

Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220218073123.2121-5-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
daniel.starke@siemens.com 2022-02-17 23:31:21 -08:00 committed by Greg Kroah-Hartman
parent 50cacb783b
commit 1bc6f3b19b
1 changed files with 4 additions and 4 deletions
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8
drivers/tty/n_gsm.c
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@ -3180,9 +3180,9 @@ static void gsmtty_throttle(struct tty_struct *tty)
if (dlci->state == DLCI_CLOSED)
return;
if (C_CRTSCTS(tty))
dlci->modem_tx &= ~TIOCM_DTR;
dlci->modem_tx &= ~TIOCM_RTS;
dlci->throttled = true;
/* Send an MSC with DTR cleared */
/* Send an MSC with RTS cleared */
gsmtty_modem_update(dlci, 0);
}
@ -3192,9 +3192,9 @@ static void gsmtty_unthrottle(struct tty_struct *tty)
if (dlci->state == DLCI_CLOSED)
return;
if (C_CRTSCTS(tty))
dlci->modem_tx |= TIOCM_DTR;
dlci->modem_tx |= TIOCM_RTS;
dlci->throttled = false;
/* Send an MSC with DTR set */
/* Send an MSC with RTS set */
gsmtty_modem_update(dlci, 0);
}