linux-kernel - Re: [PATCH] at86rf230: Allow slow GPIO pins for "rstn"

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Message-ID: <d1a4cfb5-9c0a-1bbe-1a5a-67f3f9e79d43@osg.samsung.com>
Date:   Wed, 21 Dec 2016 22:01:15 +0100
From:   Stefan Schmidt <stefan@....samsung.com>
To:     Chris Healy <cphealy@...il.com>
Cc:     Alexander Aring <aar@...gutronix.de>,
        Andrey Smirnov <andrew.smirnov@...il.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-wpan@...r.kernel.org
Subject: Re: [PATCH] at86rf230: Allow slow GPIO pins for "rstn"

Hello.

On 21/12/16 19:30, Chris Healy wrote:
>
>
> On Dec 21, 2016 5:11 AM, "Stefan Schmidt" <stefan@....samsung.com
> <mailto:stefan@....samsung.com>> wrote:
>
>     Hello.
>
>
>     On 19/12/16 00:25, Andrey Smirnov wrote:
>
>         Driver code never touches "rstn" signal in atomic context, so
>         there's
>         no need to implicitly put such restriction on it by using
>         gpio_set_value
>         to manipulate it. Replace gpio_set_value to
>         gpio_set_value_cansleep to
>         fix that.
>
>
>     We need to make sure we are not assuming it can be called  in such a
>     context in the future now. But that is something we can worry about
>     if it comes up.
>
>
>         As a an example of where such restriction might be inconvenient,
>         consider a hardware design where "rstn" is connected to a pin of
>         I2C/SPI
>         GPIO expander chip.
>
>
>     Is this a real life issue you run into?
>
>
> I have a platform with this configuration.  The DTS for the platform is
> in the process of being mainlined right now.

Thanks for letting us know. What platform is that? I'm always interested 
in hearing about devices that use the Linux ieee802154 subsystem. :)

regards
Stefan Schmidt