linux-kernel - Re: [PATCH 3/3 RESEND] mmc: sdhci: check voltage range only on regulators aware of voltage value

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Date:	Thu, 14 Feb 2013 11:03:25 +0000
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Marek Szyprowski <m.szyprowski@...sung.com>
Cc:	Guennadi Liakhovetski <g.liakhovetski@....de>,
	linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Liam Girdwood <lrg@...com>, Chris Ball <cjb@...top.org>,
	Kevin Liu <keyuan.liu@...il.com>
Subject: Re: [PATCH 3/3 RESEND] mmc: sdhci: check voltage range only on
 regulators aware of voltage value

On Thu, Feb 14, 2013 at 09:05:43AM +0100, Marek Szyprowski wrote:

> 1. mmc_regulator_get_ocrmask() works only with regulators which support
> regulator_count_voltages() and regulator_list_voltage(). Recently
> support for
> continuous regulators have been merged. Such regulators doesn't provide
> regulator_list_voltage() method, but are able to change/set voltage to the
> given value. I agree that they are not very common, so right now we can
> probably ignore them until the first board, which uses them arrives.

OK, I think this should be changed to use regulator_is_supported_voltage()
to pick a range if list_voltage() isn't there, we don't want to list an
extremely large number of voltages so using list_voltage() for continous
regulators wouldn't make sense.

> 2. The second issue might be related to the testing of precise
> voltage values
> in the ocr mask, not the whole allowed ranges. Such issues in
> sdhci.c driver
> has been recently fixed by commit cec2e216f72c6b5ccdadb60aadbe99821d744503
> ("mmc: sdhci: Use regulator min/max voltage range according to spec"), but I
> don't know MMC core code to judge if ocr mask is used for exact voltage
> checking or only for checking the voltage ranges. However someone with good
> mmc subsystem knowledge should check it.

Looking at the code I'd expect it to work with continuous regulators, if
it doesn't we should fix that.

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