tree 2fabdc048e0b773bbd6b01c6a9de8ea885ace624
parent fd2a383219261cb94917df17be8831649976f4d7
author Stephen Boyd <sboyd@codeaurora.org> 1557997723 +0800
committer Fabien Parent <parent.f@gmail.com> 1590746072 +0000

FROMLIST: PM / OPP: Support adjusting OPP voltages at runtime

On some SoCs the Adaptive Voltage Scaling (AVS) technique is
employed to optimize the operating voltage of a device. At a
given frequency, the hardware monitors dynamic factors and either
makes a suggestion for how much to adjust a voltage for the
current frequency, or it automatically adjusts the voltage
without software intervention. Add an API to the OPP library for
the former case, so that AVS type devices can update the voltages
for an OPP when the hardware determines the voltage should
change. The assumption is that drivers like CPUfreq or devfreq
will register for the OPP notifiers and adjust the voltage
according to suggestions that AVS makes.

This patch is devired from [1] submitted by Stephen.
[1] https://lore.kernel.org/patchwork/patch/599279/

(am from https://patchwork.kernel.org/patch/10946069/)

BUG=b:129039370
TEST=boot to shell

Change-Id: I1bc83a75bb0577a084c40411829fca19af8b0b58
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Roger Lu <roger.lu@mediatek.com>
Signed-off-by: Eddie Huang <eddie.huang@mediatek.com>
Reviewed-on: https://chromium-review.googlesource.com/1628412
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>