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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Mon, 24 May 2021 13:18:50 +0300
Message-ID: <CAHp75VfVNJSuiErRYNLvUrCytWXwzos5Uj87Hj+bSBee7p2YfQ@mail.gmail.com>
Subject: Re: [PATCH v3 4/6] mfd: Add RTL8231 core device
To:     Sander Vanheule <sander@svanheule.net>
Cc:     Pavel Machek <pavel@ucw.cz>, Rob Herring <robh+dt@kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Mark Brown <broonie@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Michael Walle <michael@walle.cc>,
        Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Linux LED Subsystem <linux-leds@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        Andrew Lunn <andrew@lunn.ch>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        kernel test robot <lkp@intel.com>
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On Mon, May 24, 2021 at 11:23 AM Sander Vanheule <sander@svanheule.net> wrote:
> On Mon, 2021-05-24 at 11:02 +0300, Andy Shevchenko wrote:
> > On Mon, May 24, 2021 at 1:34 AM Sander Vanheule <sander@svanheule.net> wrote:

...

> > > +       usleep_range(1000, 10000);
> >
> > It's strange to see this big range of minimum and maximum sleep.
> > Usually the ratio should not be bigger than ~3-4 between the values.
>
> I could also change this from a usleep to a polling loop that checks (with a
> loop limit) if the reset bit has self-cleared already.
>
> The datasheet that I have doesn't mention how fast it should self-clear. So I
> checked, and it appears to be done after one loop iteration already. So,
> certainly faster than the current usleep.
>
> Would a polling loop (with maybe like max. 10 iterations) be a good alternative
> for you?

I guess it's the right way to go. Just check the iopoll.h for helpers.
Also regmap has regmap_read_poll_timeout().

-- 
With Best Regards,
Andy Shevchenko