linux-kernel - Re: [PATCH 15/20] tty: n_gsm: fix missing update of modem controls after DLCI open

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Date:   Fri, 15 Apr 2022 08:29:56 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     "D. Starke" <daniel.starke@...mens.com>
Cc:     linux-serial@...r.kernel.org, jirislaby@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 15/20] tty: n_gsm: fix missing update of modem controls
 after DLCI open

On Thu, Apr 14, 2022 at 02:42:20AM -0700, D. Starke wrote:
> From: Daniel Starke <daniel.starke@...mens.com>
> 
> Currently the peer is not informed about the initial state of the modem
> control lines after a new DLCI has been opened.
> Fix this by sending the initial modem control line states after DLCI open.
> 
> Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
> Cc: stable@...r.kernel.org
> Signed-off-by: Daniel Starke <daniel.starke@...mens.com>
> ---
>  drivers/tty/n_gsm.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> index f3fb66be8513..e9a7d9483c1f 100644
> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
> @@ -369,7 +369,11 @@ static const u8 gsm_fcs8[256] = {
>  #define INIT_FCS	0xFF
>  #define GOOD_FCS	0xCF
>  
> +/*
> + * Prototypes
> + */

We know they are prototypes, no need to say it :)

>  static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len);
> +static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk);
>  
>  /**
>   *	gsm_fcs_add	-	update FCS
> @@ -1479,6 +1483,8 @@ static void gsm_dlci_open(struct gsm_dlci *dlci)
>  		pr_debug("DLCI %d goes open.\n", dlci->addr);
>  	/* Register gsmtty driver,report gsmtty dev add uevent for user */
>  	tty_register_device(gsm_tty_driver, dlci->addr, NULL);
> +	if (dlci->addr) /* Send current modem state */
> +		gsmtty_modem_update(dlci, 0);

Please do not put comments at the end of a line like this.

thanks,

greg k-h