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Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x

From Sergei Ianovich <ynvich@gmail.com>
Newsgroups linux.kernel
Subject Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x
Date 2016-03-01 18:20 +0100
Message-ID <r7W7M-3DI-21@gated-at.bofh.it> (permalink)
References <r6PL3-5Gw-3@gated-at.bofh.it> <r7Dy9-8nS-11@gated-at.bofh.it> <r7QlI-8lK-19@gated-at.bofh.it> <r7Vln-34G-3@gated-at.bofh.it> <r7VEL-3d6-21@gated-at.bofh.it>
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On Tue, 2016-03-01 at 18:46 +0200, Andy Shevchenko wrote:
> On Tue, 2016-03-01 at 19:25 +0300, Sergei Ianovich wrote:
> > On Tue, 2016-03-01 at 13:06 +0200, Andy Shevchenko wrote:
> > > On Tue, 2016-03-01 at 00:26 +0300, Sergei Ianovich wrote:
> 
> > > > +	len &= 3;
> 
> Mask as well to be defined.

Sure.

> So, but if you support only fixed rates, why do you care about BOTHER
> at all?

If BOTHER is defined, tty_termios_baud_rate()
and tty_termios_encode_baud_rate() allow non-standard baud rates. I
should clear it from c_cflag to indicate I don't support it.

> > > >  
> > > I think you can call this unconditionally together with case >
> > > 115200.
> > 
> > The calls are orthogonal. This one deals with the case when BOTHER
> > is
> > defined and set, and we have non-zero rate with BOTHER, but we have
> > zero rate after BOTHER is cleared. So we set 9600 as a sane default
> > speed.

> > 
> > This one deals with the case when the rate is over 115200. If the
> > previous case has been triggered, this one won't be.
> 
> Yeah, but I meant to unconditionally call it just once here every
> time.

I see. It saves a few lines.

> > ---
> > drivers/tty/serial/8250/8250_lp8841.c: In function
> > 'lp8841_serial_probe':
> > drivers/tty/serial/8250/8250_lp8841.c:124:32: warning: excess
> > elements in struct initializer
> >   struct uart_8250_port uart = {0};
> >                                 ^
> > drivers/tty/serial/8250/8250_lp8841.c:124:32: note: (near
> > initialization for 'uart.port.lock.<anonymous>.rlock.raw_lock')
> 
> Do you have any warning verbosity enabled? I see a lot of stuff like
> this in the code

Plain `make`.

The warning seems to be the result of initializing a spinlock with
zero. Spinlocks are intentionally obfuscated, but I didn't investigate
further.

> $ git grep -n 'struct .* = {0};' | wc -l
> 338
> 
> $ git grep -n 'struct .* = { \?0 \?};' | wc -l
> 550
> 
> ( '… = { 0 };' included)

The first structure member is most likely not a spinlock in those
cases.

> > ---
> > 
> > Zero triggers a warning. I'll use memset().
> 
> Either will work.

OK

The only remaining open point is BOTHER handling.

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Thread

[PATCH v6] serial: support for 16550A serial ports on LP-8x4x Sergei Ianovich <ynvich@gmail.com> - 2016-02-27 17:20 +0100
  Re: [PATCH v6] serial: support for 16550A serial ports on LP-8x4x Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2016-02-29 11:30 +0100
    Re: [PATCH v6] serial: support for 16550A serial ports on LP-8x4x Sergei Ianovich <ynvich@gmail.com> - 2016-02-29 14:10 +0100
      Re: [PATCH v6] serial: support for 16550A serial ports on LP-8x4x One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-02-29 15:50 +0100
  [PATCH v7] serial: support for 16550A serial ports on LP-8x4x Sergei Ianovich <ynvich@gmail.com> - 2016-02-29 22:30 +0100
    Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2016-03-01 12:10 +0100
      Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x Sergei Ianovich <ynvich@gmail.com> - 2016-03-01 17:30 +0100
        Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2016-03-01 17:50 +0100
          Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x Sergei Ianovich <ynvich@gmail.com> - 2016-03-01 18:20 +0100
            Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2016-03-01 18:50 +0100
              Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-03-01 19:50 +0100
              Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x Sergei Ianovich <ynvich@gmail.com> - 2016-03-01 20:30 +0100
                Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-03-01 21:00 +0100
    [PATCH v8] serial: support for 16550A serial ports on LP-8x4x Sergei Ianovich <ynvich@gmail.com> - 2016-03-01 21:00 +0100
      [PATCH v9] serial: support for 16550A serial ports on LP-8x4x Sergei Ianovich <ynvich@gmail.com> - 2016-03-01 21:10 +0100
        Re: [PATCH v9] serial: support for 16550A serial ports on LP-8x4x Andy Shevchenko <andy.shevchenko@gmail.com> - 2016-03-01 21:30 +0100
        [PATCH v10] serial: support for 16550A serial ports on LP-8x4x Sergei Ianovich <ynvich@gmail.com> - 2016-03-01 22:30 +0100

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