linux-kernel - Re: [PATCH][W1]w1_therm: release the bus during conversion on externally powered devices

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Message-ID: <20111117133220.GA28213@ioremap.net>
Date:	Thu, 17 Nov 2011 16:32:20 +0300
From:	Evgeniy Polyakov <zbr@...emap.net>
To:	Maciej Szmigiero <mhej@...pl>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Christian Glindkamp <christian.glindkamp@...kit.de>,
	linux-kernel@...r.kernel.org, Greg KH <greg@...ah.com>
Subject: Re: [PATCH][W1]w1_therm: release the bus during conversion on
 externally powered devices

+gregkh

On Wed, Nov 16, 2011 at 12:43:16AM +0100, Maciej Szmigiero (mhej@...pl) wrote:
> w1_therm devices can either be bus powered or externally powered.
> 
> When device is bus powered during temperature conversion the bus
> have to be left high to provide necessary power. Some masters also allow
> strong power-up to be enabled in this case.
> Naturally, no communication over bus can occur during that time.
> 
> However, if device has external power then there is no such restriction,
> and host can talk to other devices during temperature conversion.
> 
> There is command which allows us to check how device is powered,
> this patch uses it to release the bus on externally w1_therm powered devices
> during temperature conversion.
> 
> Also, this changes uninterruptible sleeps there into interruptible ones to
> avoid long uninterruptible sleep if w1 subsystem happens to grab bus for
> scan during w1_therm_read().

Patch looks good, but I do not have such hardware to test it.
So, if it doesn't break things I'm ok to push it upstream.
Greg, please pull it into your tree, thank you.

> Signed-off-by: Maciej Szmigiero <mhej@...pl>

Acked-by: Evgeniy Polyakov <zbr@...emap.net>

-- 
	Evgeniy Polyakov
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