lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Tue, 12 Aug 2014 08:13:41 -0700
From:	Doug Anderson <>
To:	Ulf Hansson <>
Cc:	Linus Walleij <>,
	Heiko Stübner <>,
	Mark Brown <>,
	Addy Ke <>,
	"" <>,
	Yuvaraj Kumar <>,
	Yuvaraj Kumar C D <>
Subject: Re: io-domain voltages as regulators?


On Mon, Aug 11, 2014 at 5:46 AM, Ulf Hansson <> wrote:
> On 11 August 2014 09:44, Linus Walleij <> wrote:
>> On Mon, Aug 4, 2014 at 12:18 AM, Heiko Stübner <> wrote:
>> [Adding Ulf Hansson to this discussion...]
>>> Hi Mark, Linus,
>>> I'd like to clarify what the appropriate way to handle pin output voltages is.
>>> On the Rockchip SoCs the voltage for some groups of pins can be set between
>>> 3.3V and 1.8V ... like the MMC/SD pins who need this to support UHS mode
>>> cards.
>> This is called "vqmmc" in the mmc/sd subsystem.
>> grep for mmc_set_signal_voltage() in drivers/mmc/core/*
>> In drivers/mmc/core/core.c, you find:
>>  mmc->supply.vqmmc = devm_regulator_get_optional(dev, "vqmmc");
>> Which gets the regulator to set the signal voltage, if such
>> a regulator is specified for the host.
>> Very simple and straight-forward, and handled by the MMC core.
>>> In [0] when talking about something different, Linus Walleij described a
>>> similar case as
>>> "I think we need to have a discussion with Mark Brown on how to
>>> handle this.
>>> We have previously had the case of MMC/SD level-shifters, where
>>> a certain setting gives a certain level of signals out, and another setting
>>> gives another level. Like two discrete levels.
>>> So we modeled that as a regulator provider inside the pin control
>>> driver eventually, see sh-pfc/pfc-sh73a0.c"
>>> As this sound like exactly the thing I'm trying to solve, is handling this via
>>> a regulator the correct general way?
>> Ithinkso.
> Just to confirm, I fully agree with the above said.
> You may also find a good example in the mmci host driver for how to
> make use of the vqmmc regulator.

Yuvaraj also submitted patches for dw_mmc:

4401241 New          [1/3] mmc: dw_mmc: use mmc_regulator_get_supply
to handle regulators
4401261 New          [2/3] mmc: dw_mmc: Dont cut off vqmmc and vmmc
4401281 New          [3/3] mmc: dw_mmc: Support voltage changes

He seems to have dropped these patches on the floor and I had review
feedback on them, but I think they're in the right direction.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists