linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Marc Zyngier <maz@kernel.org>
Cc: USB <linux-usb@vger.kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Johan Hovold <johan@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	kernel-team@android.com
Subject: Re: [PATCH 0/4] USB: ftdio_sio: GPIO validity fixes
Date: Mon, 7 Dec 2020 11:55:02 +0200	[thread overview]
Message-ID: <CAHp75VcDqHLzaAZ=EOV8EfhOxLvEC4do+UDVmAWD229xmEok+w@mail.gmail.com> (raw)
In-Reply-To: <20201204164739.781812-1-maz@kernel.org>

On Fri, Dec 4, 2020 at 6:49 PM Marc Zyngier <maz@kernel.org> wrote:
>
> Having recently tried to use the CBUS GPIOs that come thanks to the
> ftdio_sio driver, it occurred to me that the driver has a couple of
> usability issues:
>
> - it advertises potential GPIOs that are reserved to other uses (LED
>   control, or something else)
>
> - it returns an odd error (-ENODEV), instead of the expected -EINVAL
>   when a line is unavailable, leading to a difficult diagnostic
>
> We address the issues in a number of ways:
>
> - Stop reporting invalid GPIO lines as valid to userspace. It
>   definitely seems odd to do so. Instead, report the line as being
>   used, making the userspace interface a bit more consistent.
>
> - Implement the init_valid_mask() callback in the ftdi_sio driver,
>   allowing it to report which lines are actually valid.
>
> - As suggested by Linus, give an indication to the user of why some of
>   the GPIO lines are unavailable, and point them to a useful tool
>   (once per boot). It is a bit sad that there next to no documentation
>   on how to use these CBUS pins.
>
> - Drop the error reporting code, which has become useless at this
>   point.
>
> Tested with a couple of FTDI devices (FT230X and FT231X) and various
> CBUS configurations.

Series looks pretty good to me, FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Marc Zyngier (4):
>   gpiolib: cdev: Flag invalid GPIOs as used
>   USB: serial: ftdi_sio: Report the valid GPIO lines to gpiolib
>   USB: serial: ftdi_sio: Log the CBUS GPIO validity
>   USB: serial: ftdi_sio: Drop GPIO line checking dead code
>
>  drivers/gpio/gpiolib-cdev.c   |  1 +
>  drivers/usb/serial/ftdi_sio.c | 26 +++++++++++++++++++++++---
>  2 files changed, 24 insertions(+), 3 deletions(-)
>
> --
> 2.28.0
>


-- 
With Best Regards,
Andy Shevchenko

  parent reply	other threads:[~2020-12-07  9:55 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-04 16:47 Marc Zyngier
2020-12-04 16:47 ` [PATCH 1/4] gpiolib: cdev: Flag invalid GPIOs as used Marc Zyngier
2020-12-07 14:16   ` Johan Hovold
2020-12-07 14:59     ` Marc Zyngier
2020-12-09  9:25   ` Linus Walleij
2020-12-04 16:47 ` [PATCH 2/4] USB: serial: ftdi_sio: Report the valid GPIO lines to gpiolib Marc Zyngier
2020-12-09  9:28   ` Linus Walleij
2020-12-04 16:47 ` [PATCH 3/4] USB: serial: ftdi_sio: Log the CBUS GPIO validity Marc Zyngier
2020-12-07 14:29   ` Johan Hovold
2020-12-07 15:00     ` Marc Zyngier
2020-12-07 15:19       ` Johan Hovold
2020-12-09  9:35         ` Linus Walleij
2020-12-09 17:05           ` Johan Hovold
2020-12-09 17:39             ` Johan Hovold
2020-12-04 16:47 ` [PATCH 4/4] USB: serial: ftdi_sio: Drop GPIO line checking dead code Marc Zyngier
2020-12-07  9:55 ` Andy Shevchenko [this message]
2020-12-07 14:01 ` [PATCH 0/4] USB: ftdio_sio: GPIO validity fixes Johan Hovold
2020-12-07 14:41   ` Marc Zyngier
2020-12-07 15:08     ` Johan Hovold
2020-12-07 15:34       ` Marc Zyngier
2020-12-07 15:49         ` Johan Hovold
2020-12-09  9:20           ` Linus Walleij
2020-12-09 15:42             ` Johan Hovold

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='CAHp75VcDqHLzaAZ=EOV8EfhOxLvEC4do+UDVmAWD229xmEok+w@mail.gmail.com' \
    --to=andy.shevchenko@gmail.com \
    --cc=bgolaszewski@baylibre.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=johan@kernel.org \
    --cc=kernel-team@android.com \
    --cc=linus.walleij@linaro.org \
    --cc=linux-gpio@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=maz@kernel.org \
    --subject='Re: [PATCH 0/4] USB: ftdio_sio: GPIO validity fixes' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).