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From:   Bartosz Golaszewski <bgolaszewski@baylibre.com>
Date:   Thu, 28 Jan 2021 10:44:10 +0100
Message-ID: <CAMpxmJXejQjbR1qZEYTcyrFUYivJ5_U0Tchmh5V4ZqOi5NK=7A@mail.gmail.com>
Subject: Re: [PATCH] eeprom: at24: Add permission to write_timeout
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Jenny Ho <hsiufangho@google.com>, Arnd Bergmann <arnd@arndb.de>,
        linux-i2c <linux-i2c@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Thu, Jan 28, 2021 at 10:12 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Thu, Jan 28, 2021 at 10:04:42AM +0100, Bartosz Golaszewski wrote:
> > On Thu, Jan 28, 2021 at 9:10 AM Jenny Ho <hsiufangho@google.com> wrote:
> > >
> > > Need to change timeout time for different use
> > > cases to prevent I2C error cases. Open the api
> > > and allow Read/Write permission to write_timeout
> > >
> > > Signed-off-by: Jenny Ho <hsiufangho@google.com>
> > > ---
> > >  drivers/misc/eeprom/at24.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> > > index 926408b41270..39caead4058c 100644
> > > --- a/drivers/misc/eeprom/at24.c
> > > +++ b/drivers/misc/eeprom/at24.c
> > > @@ -117,7 +117,7 @@ MODULE_PARM_DESC(at24_io_limit, "Maximum bytes per I/O (default 128)");
> > >   * it's important to recover from write timeouts.
> > >   */
> > >  static unsigned int at24_write_timeout = 25;
> > > -module_param_named(write_timeout, at24_write_timeout, uint, 0);
> > > +module_param_named(write_timeout, at24_write_timeout, uint, 0600);
> > >  MODULE_PARM_DESC(at24_write_timeout, "Time (in ms) to try writes (default 25)");
> > >
> > >  struct at24_chip_data {
> > > --
> > > 2.30.0.280.ga3ce27912f-goog
> > >
> >
> > IMO this should be a per-chip device property and not a global module
> > param. Any chance you could maybe try and extend the driver with a new
> > property for that?
>
> This already is a global module parameter :)
>

I know but if we're touching it, then better do the right thing. :)

> But I agree, having it per-device would be much better, a sysfs
> attribute would easily work for that.
>

I was thinking about a generic device property that could be set from
device tree etc. I doubt there's much need to change this at runtime
outside of development?

Bart