From: Jiri Slaby <jirislaby@kernel.org>
To: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
linux-serial@vger.kernel.org,
"Greg KH" <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org,
Gilles Buloz <gilles.buloz@kontron.com>,
Johan Hovold <johan@kernel.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: Re: [PATCH 1/2] tty: Add lookahead param to receive_buf
Date: Wed, 6 Apr 2022 10:13:36 +0200 [thread overview]
Message-ID: <7cb1cc42-ef98-cbbe-1779-107602747d07@kernel.org> (raw)
In-Reply-To: <20220405102437.4842-2-ilpo.jarvinen@linux.intel.com>
On 05. 04. 22, 12:24, Ilpo Järvinen wrote:
> After lookahead for XON/XOFF characters is added by the next
> patch, the receive side needs to ensure the flow-control
> actions are not retaken later on when those same characters
> get read by TTY.
>
> Thus, pass lookahead count to receive_buf and skip
> flow-control character actions if already taken for the
> character in question. Lookahead count will become live after
> the next patch.
...
> --- a/include/linux/tty_ldisc.h
> +++ b/include/linux/tty_ldisc.h
> @@ -224,11 +224,11 @@ struct tty_ldisc_ops {
> * The following routines are called from below.
> */
> void (*receive_buf)(struct tty_struct *tty, const unsigned char *cp,
> - const char *fp, int count);
> + const char *fp, int count, int lookahead_count);
> void (*write_wakeup)(struct tty_struct *tty);
> void (*dcd_change)(struct tty_struct *tty, unsigned int status);
> int (*receive_buf2)(struct tty_struct *tty, const unsigned char *cp,
> - const char *fp, int count);
> + const char *fp, int count, int lookahead_count);
Please always use unsigned if you don't expect negative numbers. count
should be changed to unsigned in long term too.
> diff --git a/include/linux/tty_port.h b/include/linux/tty_port.h
> index 58e9619116b7..1871a6a9cb00 100644
> --- a/include/linux/tty_port.h
> +++ b/include/linux/tty_port.h
> @@ -39,7 +39,7 @@ struct tty_port_operations {
> };
>
> struct tty_port_client_operations {
> - int (*receive_buf)(struct tty_port *port, const unsigned char *, const unsigned char *, size_t);
> + int (*receive_buf)(struct tty_port *port, const unsigned char *, const unsigned char *, size_t, size_t);
Good, here it is unsigned and even of size_t size (I don't immediately
see why, but OK).
thanks,
--
js
suse labs
next prev parent reply other threads:[~2022-04-06 11:25 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-05 10:24 [PATCH 0/2] tty/serial: Process XON/XOFF robustly Ilpo Järvinen
2022-04-05 10:24 ` [PATCH 1/2] tty: Add lookahead param to receive_buf Ilpo Järvinen
2022-04-05 16:03 ` Andy Shevchenko
2022-04-06 8:07 ` Jiri Slaby
2022-04-06 8:13 ` Jiri Slaby [this message]
2022-04-06 8:46 ` Ilpo Järvinen
2022-04-05 10:24 ` [PATCH 2/2] tty: Implement lookahead to process XON/XOFF timely Ilpo Järvinen
2022-04-05 16:11 ` Andy Shevchenko
2022-04-06 8:21 ` Jiri Slaby
2022-04-06 8:50 ` Ilpo Järvinen
2022-04-06 8:54 ` Andy Shevchenko
2022-04-06 8:56 ` Andy Shevchenko
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