From: Johan Hovold <johan@kernel.org>
To: Jiri Slaby <jslaby@suse.cz>
Cc: gregkh@linuxfoundation.org, linux-serial@vger.kernel.org,
linux-kernel@vger.kernel.org,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Joe Perches <joe@perches.com>
Subject: Re: [PATCH v2 34/35] tty: make tty_get_byte_size available
Date: Thu, 13 May 2021 11:41:06 +0200 [thread overview]
Message-ID: <YJz0MqOOzrIBjDBL@hovoldconsulting.com> (raw)
In-Reply-To: <f8f94397-14d8-60d0-f977-8bc982a00b7a@suse.cz>
On Thu, May 13, 2021 at 09:24:03AM +0200, Jiri Slaby wrote:
> On 10. 05. 21, 11:47, Johan Hovold wrote:
> >> --- a/drivers/tty/tty_ioctl.c
> >> +++ b/drivers/tty/tty_ioctl.c
> >> @@ -300,6 +300,48 @@ int tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b)
> ...
> >> +unsigned char tty_get_byte_size(unsigned int cflag, bool account_flags)
> >> +{
> >> + unsigned char bits;
> >> +
> >> + switch (cflag & CSIZE) {
> >> + case CS5:
> >> + bits = 5;
> >> + break;
> >> + case CS6:
> >> + bits = 6;
> >> + break;
> >> + case CS7:
> >> + bits = 7;
> >> + break;
> >> + case CS8:
> >> + default:
> >> + bits = 8;
> >> + break;
> >> + }
> >> +
> >> + if (!account_flags)
> >> + return bits;
> >> +
> >> + if (cflag & CSTOPB)
> >> + bits++;
> >> + if (cflag & PARENB)
> >> + bits++;
> >> +
> >> + return bits + 2;
> >> +}
> >> +EXPORT_SYMBOL_GPL(tty_get_byte_size);
> >
> > This should really be two functions rather than passing a bool argument.
> >
> > I think naming them
> >
> > tty_get_word_size()
> >
> > and
> >
> > tty_get_frame_size()
> >
> > would be much more clear than than "byte size" + flag.
>
> Maybe I am screwed, but word means exactly 2B here.
No, not in this context.
Some UART datasheets use "word" and "word length", while others use
"character length" or "data bits" (and variations thereof).
> So instead, I would
> go for:
> s/word/char/ -- might be confused with C's char, 1B, or maybe not -- or
> s/word/data/ -- more generic and generally used in serial terminology.
But "data size" it not very precise.
I'd go for either
tty_get_word_size() or tty_get_char_size(), and
tty_get_frame_size()
or possibly
tty_get_data_bits(), and
tty_get_frame_bits()
Since posix and the termios interface use "CSIZE" (even if that "C" is
ambiguous) and our man pages use "character size" perhaps we should
stick with that and use:
tty_get_char_size(), and
tty_get_frame_size()
That should be clear enough for everyone.
> > I realise that the serial-driver interface only uses a cflag argument,
> > but I think we should consider passing a pointer to the termios
> > structure instead.
>
> That's impossible as termios is not always at hand. Examples are:
> pch_uart_startup -> uart_update_timeout
> sunsab_console_setup -> sunsab_convert_to_sab -> uart_update_timeout
> sunsu_kbd_ms_init -> sunsu_change_speed -> uart_update_timeout
>
> Let me document that in the commit.
Sounds good.
Johan
next prev parent reply other threads:[~2021-05-13 9:41 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-05 9:18 [PATCH 00/35] tty cleanup for 5.14 Jiri Slaby
2021-05-05 9:18 ` [PATCH 01/35] tty: remove broken r3964 line discipline Jiri Slaby
2021-05-05 9:26 ` Greg KH
2021-05-05 9:18 ` [PATCH 02/35] n_tty: remove n_tty_receive_char wrapper Jiri Slaby
2021-05-05 9:18 ` [PATCH 03/35] n_tty: remove n_tty_receive_char_fast Jiri Slaby
2021-05-05 9:18 ` [PATCH 04/35] n_tty: drop n_tty_receive_buf_fast Jiri Slaby
2021-05-05 9:18 ` [PATCH 05/35] n_tty: drop parmrk_dbl from n_tty_receive_char Jiri Slaby
2021-05-05 9:18 ` [PATCH 06/35] n_tty: move lnext handling Jiri Slaby
2021-05-05 9:19 ` [PATCH 07/35] n_tty: make n_tty_receive_char_special return void Jiri Slaby
2021-05-05 9:19 ` [PATCH 08/35] n_tty: do only one cp dereference in n_tty_receive_buf_standard Jiri Slaby
2021-05-05 9:19 ` [PATCH 09/35] n_tty: invert TTY_NORMAL condition " Jiri Slaby
2021-05-05 9:19 ` [PATCH 10/35] n_tty: remove superfluous return from n_tty_receive_signal_char Jiri Slaby
2021-05-05 9:19 ` [PATCH 11/35] tty: make fp of tty_ldisc_ops::receive_buf{,2} const Jiri Slaby
2021-05-05 9:19 ` [PATCH 12/35] tty: cumulate and document tty_struct::flow* members Jiri Slaby
2021-05-05 9:19 ` [PATCH 13/35] tty: cumulate and document tty_struct::ctrl* members Jiri Slaby
2021-05-05 9:19 ` [PATCH 14/35] tty: set tty_ldisc_ops::num statically Jiri Slaby
2021-05-05 9:19 ` [PATCH 15/35] n_gsm: use goto-failpaths in gsm_init Jiri Slaby
2021-05-05 9:19 ` [PATCH 16/35] tty: make tty_ldisc_ops a param in tty_unregister_ldisc Jiri Slaby
2021-05-05 9:19 ` [PATCH 17/35] tty: drop tty_ldisc_ops::refcount Jiri Slaby
2021-05-05 9:19 ` [PATCH 18/35] tty: no checking of tty_unregister_ldisc Jiri Slaby
2021-05-05 9:19 ` [PATCH 19/35] tty: return void from tty_unregister_ldisc Jiri Slaby
2021-05-05 9:19 ` [PATCH 20/35] ti-st: use goto-failpath in st_core_init Jiri Slaby
2021-05-05 9:19 ` [PATCH 21/35] ti-st: use tty_write_room Jiri Slaby
2021-05-05 9:19 ` [PATCH 22/35] tty: make tty_operations::write_room return uint Jiri Slaby
2021-05-05 9:25 ` Geert Uytterhoeven
2021-05-05 10:34 ` Anton Ivanov
2021-05-05 10:43 ` David Sterba
2021-05-05 11:53 ` Max Filippov
2021-05-05 12:15 ` Alex Elder
2021-05-10 11:27 ` Laurentiu Tudor
2021-05-05 9:19 ` [PATCH 23/35] USB: serial: make usb_serial_driver::write_room " Jiri Slaby
2021-05-19 9:07 ` Johan Hovold
2021-05-05 9:19 ` [PATCH 24/35] tty: make tty_buffer_space_avail " Jiri Slaby
2021-05-05 9:19 ` [PATCH 25/35] tty: remove tty_operations::chars_in_buffer for non-buffering Jiri Slaby
2021-05-05 11:51 ` Max Filippov
2021-05-06 5:47 ` Jiri Slaby
2021-05-06 5:56 ` Greg KH
2021-05-05 9:19 ` [PATCH 26/35] tty: make tty_operations::chars_in_buffer return uint Jiri Slaby
2021-05-05 10:34 ` Anton Ivanov
2021-05-05 10:43 ` David Sterba
2021-05-05 9:19 ` [PATCH 27/35] serial: make usb_serial_driver::chars_in_buffer " Jiri Slaby
2021-05-19 9:09 ` Johan Hovold
2021-05-05 9:19 ` [PATCH 28/35] nozomi: simplify ntty_chars_in_buffer Jiri Slaby
2021-05-05 9:19 ` [PATCH 29/35] USB: serial: digi_acceleport, simplify digi_chars_in_buffer Jiri Slaby
2021-05-19 9:11 ` Johan Hovold
2021-05-05 9:19 ` [PATCH 30/35] tty: remove empty tty_operations::flush_buffer Jiri Slaby
2021-05-05 9:19 ` [PATCH 31/35] tty: remove empty tty_operations::set_termios Jiri Slaby
2021-05-05 10:34 ` Anton Ivanov
2021-05-05 9:19 ` [PATCH 32/35] isdn: capi, remove optional tty ops Jiri Slaby
2021-05-05 9:19 ` [PATCH 33/35] isdn: capi, drop useless pr_debugs Jiri Slaby
2021-05-05 9:19 ` [PATCH 34/35] tty: make tty_get_byte_size available Jiri Slaby
2021-05-06 7:16 ` Joe Perches
2021-05-06 7:19 ` Jiri Slaby
[not found] ` <CAHp75Vfq6ABW7ukwaKmZOF2DszmuHD28S=wcLcFowvRdXTnWmg@mail.gmail.com>
2021-05-06 8:31 ` Jiri Slaby
2021-05-06 9:33 ` Andy Shevchenko
2021-05-06 8:35 ` Joe Perches
2021-05-10 7:00 ` [PATCH v2 " Jiri Slaby
2021-05-10 9:47 ` Johan Hovold
2021-05-13 7:24 ` Jiri Slaby
2021-05-13 9:41 ` Johan Hovold [this message]
2021-05-05 9:19 ` [PATCH 35/35] tty: make use of tty_get_byte_size Jiri Slaby
2021-05-10 9:59 ` Johan Hovold
2021-05-13 15:04 ` [PATCH 00/35] tty cleanup for 5.14 Greg KH
2021-05-13 16:20 ` Johan Hovold
2021-05-13 16:29 ` Greg KH
2021-05-14 8:11 ` Johan Hovold
2021-06-10 9:02 ` [PATCH v3 1/4] tty: make tty_get_{char,frame}_size available Jiri Slaby
2021-06-10 9:02 ` [PATCH v3 2/4] mxs-auart: redefine AUART_LINECTRL_WLEN to accept bits count Jiri Slaby
2021-06-10 9:02 ` [PATCH v3 3/4] cypress_m8: switch data_bits to real character bits Jiri Slaby
2021-06-10 9:02 ` [PATCH v3 4/4] tty: make use of tty_get_{char,frame}_size Jiri Slaby
2021-06-10 15:15 ` Alex Elder
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