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 <inderpa...@samsung.com> Doug Anderson <diand...@chromium.org> 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. Note on the locking model: When balancing voltage of a group of coupled regulators, we lock all of them for the whole operation. When voltage of an individual regulator is about to change, its suppliers are additionally locked. The current assumption is that an uncoupled regulator is a special case of a coupled one, so they should share a common voltage setting path. Best regards, Maciej Purski --- Changes in v5: - rebase against current Mark Brown's regulators next Changes in v4: - make paths for coupled and uncoupled regulators common - coupling descriptors are now always present in regulator_dev - fail to probe if data inconsistency is detected - retry to resolve coupling regultors in late init call - rebase on top of linux-next 20180119 - fix commit messages - split patches to make the patchset easier to review Changes in v3: - move dts parsing code to of_regulator.c, in order to the so, add a new commit in which of_regulator_find_by_node() is moved to of_regulator.c as well - improve error messages - move max_spread variable to constraints - perform resolving of coupled regulators under a list mutex - remove useless locking functions - some minor refactorization - improve commit messages 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 (5): regulator: bindings: Add properties for coupled regulators regulator: core: Parse coupled regulators properties regulator: core: Resolve coupled regulators regulator: core: Add voltage balancing mechanism regulator: core: Change voltage setting path .../devicetree/bindings/regulator/regulator.txt | 5 + drivers/regulator/core.c | 381 ++++++++++++++++++++- drivers/regulator/internal.h | 6 + drivers/regulator/of_regulator.c | 149 ++++++++ include/linux/regulator/driver.h | 18 + include/linux/regulator/machine.h | 4 + 6 files changed, 545 insertions(+), 18 deletions(-) -- 2.7.4