linux-kernel - Re: [PATCH 3/3] iio: magnetometer: ak8975: Add gpio reset support

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Message-ID: <20200529133346.GC1339@bug>
Date:   Fri, 29 May 2020 15:33:46 +0200
From:   Pavel Machek <pavel@....cz>
To:     Jonathan Albrieux <jonathan.albrieux@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hartmut Knaack <knaack.h@....de>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        "open list:IIO SUBSYSTEM AND DRIVERS" <linux-iio@...r.kernel.org>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Steve Winslow <swinslow@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jonathan Cameron <jic23@...nel.org>
Subject: Re: [PATCH 3/3] iio: magnetometer: ak8975: Add gpio reset support

Hi!

> AK09911 has a reset gpio to handle register's reset. If reset gpio is
> set to low it will trigger the reset. AK09911 datasheed says that if not
> used reset pin should be connected to VID and this patch emulates this
> situation
> 
> Signed-off-by: Jonathan Albrieux <jonathan.albrieux@...il.com>
> ---
>  drivers/iio/magnetometer/ak8975.c | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
> 
>  	/*
> -	 * According to the datasheet the power supply rise time i 200us
> +	 * According to the datasheet the power supply rise time is 200us
>  	 * and the minimum wait time before mode setting is 100us, in
> -	 * total 300 us. Add some margin and say minimum 500us here.
> +	 * total 300us. Add some margin and say minimum 500us here.
>  	 */
>  	usleep_range(500, 1000);

I'd assume that datasheet added some safety margin too, and there's another one in usleep...
So I believe usleep..(300) should be okay..

Best regards,
										Pavel