All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
To: Antony Pavlov <antonynpavlov@gmail.com>
Cc: barebox@lists.infradead.org
Subject: Re: [RFC] ns16550: support for UART with broken FIFO
Date: Wed, 18 Jan 2012 00:58:38 +0100	[thread overview]
Message-ID: <20120117235838.GF25622@game.jcrosoft.org> (raw)
In-Reply-To: <CAA4bVAFLHb6idJ6yUa5ZNDYdBTKroAE4g2_u=YAZ7XB2MCLGrw@mail.gmail.com>

On 23:40 Tue 17 Jan     , Antony Pavlov wrote:
> On 17 January 2012 18:53, Jean-Christophe PLAGNIOL-VILLARD
> <plagnioj@jcrosoft.com> wrote:
> > On 17:27 Tue 17 Jan     , Antony Pavlov wrote:
> >> On 17 January 2012 17:09, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> >> > On Tue, Jan 17, 2012 at 02:39:06PM +0400, Antony Pavlov wrote:
> >> >> Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
> >> >> ---
> >> >>  drivers/serial/serial_ns16550.c |   19 +++++++++++++++++--
> >> >>  include/ns16550.h               |    2 ++
> >> >>  2 files changed, 19 insertions(+), 2 deletions(-)
> >> >>
> >> >> diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c
> >> >> index 1217a5f..01de964 100644
> >> >> --- a/drivers/serial/serial_ns16550.c
> >> >> +++ b/drivers/serial/serial_ns16550.c
> >> >> @@ -139,6 +139,8 @@ static unsigned int ns16550_calc_divisor(struct console_device *cdev,
> >> >>  static void ns16550_serial_init_port(struct console_device *cdev)
> >> >>  {
> >> >>       unsigned int baud_divisor;
> >> >> +     struct NS16550_plat *plat = (struct NS16550_plat *)
> >> >> +         cdev->dev->platform_data;
> >> >>
> >> >>       /* Setup the serial port with the defaults first */
> >> >>       baud_divisor = ns16550_calc_divisor(cdev, CONFIG_BAUDRATE);
> >> >> @@ -153,7 +155,13 @@ static void ns16550_serial_init_port(struct console_device *cdev)
> >> >>       ns16550_write(cdev, (baud_divisor >> 8) & 0xff, dlm);
> >> >>       ns16550_write(cdev, LCRVAL, lcr);
> >> >>       ns16550_write(cdev, MCRVAL, mcr);
> >> >> -     ns16550_write(cdev, FCRVAL, fcr);
> >> >> +
> >> >> +     if (plat->flags & NS16650_FLAG_DISABLE_FIFO) {
> >> >> +             ns16550_write(cdev, FCRVAL & ~FCR_FIFO_EN, fcr);
> >> >> +     } else {
> >> >> +             ns16550_write(cdev, FCRVAL, fcr);
> >> >> +     }
> >> >
> >> > unnecessary braces here..
> >> >
> >> >> +
> >> >>  #ifdef CONFIG_DRIVER_SERIAL_NS16550_OMAP_EXTENSIONS
> >> >>       ns16550_write(cdev, 0x00,  mdr1);
> >> >>  #endif
> >> >> @@ -211,6 +219,8 @@ static int ns16550_tstc(struct console_device *cdev)
> >> >>  static int ns16550_setbaudrate(struct console_device *cdev, int baud_rate)
> >> >>  {
> >> >>       unsigned int baud_divisor = ns16550_calc_divisor(cdev, baud_rate);
> >> >> +     struct NS16550_plat *plat = (struct NS16550_plat *)
> >> >> +         cdev->dev->platform_data;
> >> >>
> >> >>       ns16550_write(cdev, 0x00, ier);
> >> >>       ns16550_write(cdev, LCR_BKSE, lcr);
> >> >> @@ -218,7 +228,12 @@ static int ns16550_setbaudrate(struct console_device *cdev, int baud_rate)
> >> >>       ns16550_write(cdev, (baud_divisor >> 8) & 0xff, dlm);
> >> >>       ns16550_write(cdev, LCRVAL, lcr);
> >> >>       ns16550_write(cdev, MCRVAL, mcr);
> >> >> -     ns16550_write(cdev, FCRVAL, fcr);
> >> >> +     if (plat->flags & NS16650_FLAG_DISABLE_FIFO) {
> >> >> +             ns16550_write(cdev, FCRVAL & ~FCR_FIFO_EN, fcr);
> >> >> +     } else {
> >> >> +             ns16550_write(cdev, FCRVAL, fcr);
> >> >> +     }
> >> >
> >> > and here. Otherwise this looks ok.
> >>
> >> Ok, I shall remove the braces.
> >>
> >> Sascha!
> >>
> >> We have special OMAP code, e.g.:
> >>
> >> #ifdef CONFIG_DRIVER_SERIAL_NS16550_OMAP_EXTENSIONS
> >>         ns16550_write(cdev, 0x07, mdr1);        /* Disable */
> >> #endif
> >>
> >> I think, that we can change it to something like this:
> >>
> >>     if (plat->flags & NS16650_FLAG_OMAP_EXTENSIONS)
> >>         ns16550_write(cdev, 0x07, mdr1);        /* Disable */
> > I don't like to add dead code in the binary
> > just use
> >        if (IS_ENABLED(CONFIG_...)
> 
> You is right, but there is another point of view.
> 
> If you have defined CONFIG_DRIVER_SERIAL_NS16550_OMAP_EXTENSIONS
> macro, then you will use OMAP extensions for __ALL__ ports, not only
> for OMAP internal port. May be OMAP have no other ports, only internal
> ports with extensions. But in any case it is bad design example: we
> have very special code (OMAP EXTENSIONS) in universal driver
> (ns16550), and this special code works without checking presents of
> the extensions.
> 
> I don't like dead code too. So there are another solutions:
> 
> #ifdef CONFIG_DRIVER_SERIAL_NS16550_OMAP_EXTENSIONS
>         if (plat->flags & NS16650_FLAG_OMAP_EXTENSIONS)
>             ns16550_write(cdev, 0x07, mdr1);        /* Disable */
> #endif
> 
> or even
>         if (IS_ENABLED(CONFIG_DRIVER_SERIAL_NS16550_OMAP_EXTENSIONS) &&
>          plat->flags & NS16650_FLAG_OMAP_EXTENSIONS)
>             ns16550_write(cdev, 0x07, mdr1);        /* Disable */
this one

Best Regards,
J.
> -- 
> Best regards,
>   Antony Pavlov

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

      reply	other threads:[~2012-01-17 23:59 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-17 10:39 [RFC] ns16550: support for UART with broken FIFO Antony Pavlov
2012-01-17 13:09 ` Sascha Hauer
2012-01-17 13:27   ` Antony Pavlov
2012-01-17 14:53     ` Jean-Christophe PLAGNIOL-VILLARD
2012-01-17 19:40       ` Antony Pavlov
2012-01-17 23:58         ` Jean-Christophe PLAGNIOL-VILLARD [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20120117235838.GF25622@game.jcrosoft.org \
    --to=plagnioj@jcrosoft.com \
    --cc=antonynpavlov@gmail.com \
    --cc=barebox@lists.infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.