linux-kernel - Re: [PATCH] w1-gpio: add external pull-up enable callback

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Message-ID: <20090506093307.GC17782@sci.fi>
Date:	Wed, 6 May 2009 12:33:07 +0300
From:	Ville Syrjälä <syrjala@....fi>
To:	Daniel Mack <daniel@...aq.de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] w1-gpio: add external pull-up enable callback

On Tue, May 05, 2009 at 02:43:33PM +0200, Daniel Mack wrote:
> On embedded devices, sleep mode conditions can be tricky to handle,
> Especially when processors tend to pull-down the w1 bus during sleep.
> Bus slaves (such as the ds2760) may interpret this as a reason for
> power-down conditions and entirely switch off the device.
> 
> This patch adds a callback function pointer to let users switch on and
> off the external pull-up resistor. This lets the outside world know
> whether the processor is currently actively driving the bus or not.

Looks simple enough but I wonder if you could just do this from the
platform code. I suppose the downside would be that you would enable the
pullup even if w1-gpio is not loaded.

-- 
Ville Syrjälä
syrjala@....fi
http://www.sci.fi/~syrjala/
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