Hi all, this patchset adds a new mechanism to the framework - regulators' coupling. On Odroid XU3/4 and other Exynos5422 based boards there is a case, that different devices on the board are supplied by different regulators with non-fixed voltages. If one of these devices temporarily requires higher voltage, there might occur a situation that the spread between devices' voltages is so high, that there is a risk of changing 'high' and 'low' states on the interconnection between devices powered by those regulators. Algorithmicaly the problem was solved by: Inderpal Singh <inderpal.s@xxxxxxxxxxx> Doug Anderson <dianders@xxxxxxxxxxxx> The discussion on that subject can be found here: https://lkml.org/lkml/2014/4/29/28 Therefore this patchset is an attempt to apply the idea to regulators core as concluded in the discussion by Mark Brown and Doug Anderson. This feature is required to enable support for generic CPUfreq and devfreq drivers for the mentioned boards. Open question - which locking model should be used, because during balancing voltages we need to lock all coupled regulators and their parents. Unfortunately, some coupled regulators might have common parents. I can see three possibilities here: 1. (current implementation) Always lock all coupled regulators and additionally lock parents only for changing voltage of the individual regulator 2. Always lock all coupled regulators and their parents - to avoid deadlock on common parent, first enumerate locks, then sort them and remove double entries 3. Always lock all coupled regulators and their parents - to avoid deadlock on common parent, introduce so called reentrant locks (lock which might be taken multiple times by the same process). Best regards, Maciej Purski -- Changes in RFC v2: - allow coupling n regulators (in fact up to constant value, now set to 10) - change algorithm to be more readable - introduce better locking - add more comments - split first patch into two - update commit messages - change sequence of the patches Maciej Purski (3): regulator: bindings: Add properties for coupled regulators regulator: core: Parse coupled regulators properties regulator: core: Balance coupled regulators voltages .../devicetree/bindings/regulator/regulator.txt | 4 + drivers/regulator/core.c | 487 ++++++++++++++++++++- include/linux/regulator/driver.h | 17 + 3 files changed, 492 insertions(+), 16 deletions(-) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
