linux-kernel - Re: [PATCH v3 2/4] MFD MAX8998/LP3974: Support LP3974 RTC

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Message-ID: <20101224113805.GI27832@sortiz-mobl>
Date:	Fri, 24 Dec 2010 12:38:06 +0100
From:	Samuel Ortiz <sameo@...ux.intel.com>
To:	MyungJoo Ham <myungjoo.ham@...sung.com>
Cc:	linux-kernel@...r.kernel.org, Liam Girdwood <lrg@...mlogic.co.uk>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Joonyoung Shim <jy0922.shim@...sung.com>,
	Lukasz Majewski <l.majewski@...sung.com>,
	myungjoo.ham@...il.com
Subject: Re: [PATCH v3 2/4] MFD MAX8998/LP3974: Support LP3974 RTC

Hi MyungJoo,

On Thu, Dec 23, 2010 at 05:53:37PM +0900, MyungJoo Ham wrote:
> The first releases of LP3974 have a large delay in RTC registers,
> which requires 2 seconds of delay after writing to a rtc register
> (recommended by National Semiconductor's engineers)
> before reading it. If the device name is "lp3974-regerr", the rtc driver
> assumes that such delays are required. If the device name is "lp3974",
> the rtc driver does not. Although we have not seen LP3974s without
> requiring such delays, we assume that such LP3974s will be released
> soon (or they have done so already) and they are supported by "lp3974".
> 
> This patch adds delays with msleep when writing values to RTC registers
> if the device name is "lp3974-regerr".
As Mark pointed out, I'd prefer to add a regerr flag to the driver platform
data and decide which cell to add from there.

Cheers,
Samuel.

-- 
Intel Open Source Technology Centre
http://oss.intel.com/
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