Re: FW: [PATCH v2] mmc: sdhci: apply voltage range check only fornon-fixed regulators
From: Mark Brown
Date: Wed Nov 14 2012 - 03:41:04 EST
On Wed, Nov 14, 2012 at 04:36:28PM +0800, Kevin Liu wrote:
> 2012/11/14 Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx>:
> > Should this be regulator_set_voltage_tol()? Otherwise it'd be good to
> > explain where the numbers come from.
> In SD physical layer spec 3.01 chapter 6.6.1, the threshold level for
> voltage range is defined as below:
> Vdd(min) = 2.7V while Vdd(max) = 3.6V.
> The card should work within the voltage range.
> If you are afraid the voltage value is too aggressive, maybe we can
> use regulator_set_voltage_tol() to set a smaller range.
> But which range should be reasonable?
The above makes total sense - thanks! I just wasn't aware that the
range was specified in this fashion in the spec. Might be worth a
comment in the code if you need to respin.
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