[PATCH 0/2] IO voltage domain support for rk3188 and rk3288

Linus Walleij [off-list ref] writes:

On Sat, Aug 30, 2014 at 1:27 PM, Heiko St?bner [off-list ref] wrote:

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Am Freitag, 29. August 2014, 21:51:46 schrieb Doug Anderson:

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On Thu, Aug 28, 2014 at 2:26 PM, Santosh Shilimkar

[off-list ref] wrote:

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On Thursday 28 August 2014 03:36 PM, Doug Anderson wrote:

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These two patches add support for automatically configuring the IO
voltage domains on rk3188 and rk3288 SoCs.  The first patch adds some
new notification types to the regulator code.  It's used by the second
patch which actually implements the IO voltage domain driver.

These two patches were co-developed by Heiko St?bner and Doug Anderson
(proof of concept patches were written by Heiko).  They were tested in
a private branch on an rk3288 board using rk808 instead of mainline
since rk808 support isn't finalized in mainline yet.

(sorry if you got this series twice; my mailer seems unhappy with me)

Heiko St?bner (2):
  regulator: core: Add REGULATOR_EVENT_PRE_VOLTAGE_CHANGE (and ABORT)
  soc/rockchip: io-domain: add driver handling io domains

Sorry to shot down but your IO domains are nothing but voltage domains
and you should really build something in the drivers/power/*

If everyone agrees that this belongs in drivers/power that's totally
OK.  Neither Heiko nor I was confident that it should be in
drivers/soc.  I had even though that the code wouldn't be totally out
of place in the Rockchip pinctrl driver (adding Linus W since I think
some SoCs did add code to handle 3.3V vs. 1.8V in pinctrl).

a bit of context for Linus ...

This is essentially the continuation of  the thread "io-domain voltages as
regulators?" from the beginning of august. After more discussions we found out
that the io voltage selection I asked about is not an independent supply, but
instead has to reflect the voltage of the real supplying regulator.

And setting the io-voltage setting to 1.8V while the regulator is supplying
3.3V for example may actually damage the chip.


So in our current approach here, we added a driver that tracks voltage changes
of the supplying regulator via a notifier and sets the register bits
accordingly.

I feel I'm not smart enough for this. You need the PM people to look
at this stuff, like Rafael Wysocki, Kevin Hilman and Ulf Hansson.

I think the best fit for this is along with the Adaptive Voltage Scaling
(AVS) stuff we currently have in drivers/power/avs.  It's not exactly
adaptive in the same sense as the TI/SmartReflex is because there's no
hardware being configured to dynamically make micro-adjustments to the
regulators.  But, it is adaptive in the sense that there's SoC-specific
"stuff" to do right around the same time the voltage is scaled.

So I would suggest drivers/power/avs.

Kevin