linux-kernel - Re: [PATCH v3 1/2] hwmon: (lm90) Add power control

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Message-ID: <522F02A4.7060702@nvidia.com>
Date:	Tue, 10 Sep 2013 19:29:40 +0800
From:	Wei Ni <wni@...dia.com>
To:	Mark Brown <broonie@...nel.org>
CC:	Guenter Roeck <linux@...ck-us.net>,
	"khali@...ux-fr.org" <khali@...ux-fr.org>,
	"swarren@...dotorg.org" <swarren@...dotorg.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] hwmon: (lm90) Add power control

On 09/10/2013 06:13 PM, Mark Brown wrote:
> * PGP Signed by an unknown key
> 
> On Tue, Sep 10, 2013 at 01:39:59PM +0800, Wei Ni wrote:
> 
>> I think the device need time to wait stable after power on, but it's
>> difficult to get an exact delay value, and this delay may also relate
>> with platform design, so how about to add a optional property in the DT
>> node, such as "power-on-delay-ms" ?
> 
> This is something you should *really* be able to get from the datasheet
> for the part - this sort of stuff has to be documented for hardware to
> be used robustly.  It seems entirely possible that you are working
> around an issue with the regulator driver you are using not correctly
> providing its ramp time here.

On my platform, it use palmas-regulator.c, ldo6 for this lm90 power
rail. I checked this driver, it will handle ramp_delay except LDOx.
Since I'm not familiar with this palmas device and driver, so do you
mean I can set regulator-ramp-delay property in the DT for ldo6, but I
really don't know what value should I set :(

Thanks.
Wei.

> 
> * Unknown Key
> * 0x7EA229BD
> 

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