The patch regulator: core: Add voltage balancing mechanism has been applied to the regulator tree at https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted. You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed. If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced. Please add any relevant lists and maintainers to the CCs when replying to this mail. Thanks, Mark >From 696861761a58d8c93605b5663824929fb6540f16 Mon Sep 17 00:00:00 2001 From: Maciej Purski <m.purski@xxxxxxxxxxx> Date: Mon, 23 Apr 2018 16:33:41 +0200 Subject: [PATCH] regulator: core: Add voltage balancing mechanism 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 two 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. Introduce new function regulator_balance_voltage(), which keeps max_spread constraint fulfilled between a group of coupled regulators. It should be called if a regulator changes its voltage or after disabling or enabling. Disabled regulators should follow changes of the enabled ones, but their consumers' demands shouldn't be taken into account while calculating voltage of other coupled regulators. Find voltages, which are closest to suiting all the consumers' demands, while fulfilling max_spread constraint, keeping the following rules: - if one regulator is about to rise its voltage, rise others voltages in order to keep the max_spread - if a regulator, which has caused rising other regulators, is lowered, lower other regulators if possible - if one regulator is about to lower its voltage, but it hasn't caused rising other regulators, don't change its voltage if it breaks the max_spread Change regulators' voltages step by step, keeping max_spread constraint fulfilled all the time. Function regulator_get_optimal_voltage() should find the best possible change for the regulator, which doesn't break max_spread constraint. In function regulator_balance_voltage() optimize number of steps by finding highest voltage difference on each iteration. If a regulator, which is about to change its voltage, is not coupled, method regulator_get_optimal_voltage() should simply return the lowest voltage fulfilling consumers' demands. Coupling should be checked only if the system is in PM_SUSPEND_ON state. Signed-off-by: Maciej Purski <m.purski@xxxxxxxxxxx> Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> --- drivers/regulator/core.c | 192 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 192 insertions(+) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 6ed568b96c0e..225eaca24921 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -105,6 +105,8 @@ static int _notifier_call_chain(struct regulator_dev *rdev, unsigned long event, void *data); static int _regulator_do_set_voltage(struct regulator_dev *rdev, int min_uV, int max_uV); +static int regulator_balance_voltage(struct regulator_dev *rdev, + suspend_state_t state); static struct regulator *create_regulator(struct regulator_dev *rdev, struct device *dev, const char *supply_name); @@ -3102,6 +3104,196 @@ static int regulator_set_voltage_unlocked(struct regulator *regulator, return ret; } +static int regulator_get_optimal_voltage(struct regulator_dev *rdev) +{ + struct coupling_desc *c_desc = &rdev->coupling_desc; + struct regulator_dev **c_rdevs = c_desc->coupled_rdevs; + int max_spread = rdev->constraints->max_spread; + int n_coupled = c_desc->n_coupled; + int desired_min_uV, desired_max_uV, min_current_uV = INT_MAX; + int max_current_uV = 0, highest_min_uV = 0, target_uV, possible_uV; + int i, ret; + + /* If consumers don't provide any demands, set voltage to min_uV */ + desired_min_uV = rdev->constraints->min_uV; + desired_max_uV = rdev->constraints->max_uV; + ret = regulator_check_consumers(rdev, + &desired_min_uV, + &desired_max_uV, PM_SUSPEND_ON); + if (ret < 0) + goto out; + + /* + * If there are no coupled regulators, simply set the voltage demanded + * by consumers. + */ + if (n_coupled == 1) { + ret = desired_min_uV; + goto out; + } + + /* Find highest min desired voltage */ + for (i = 0; i < n_coupled; i++) { + int tmp_min = 0; + int tmp_max = INT_MAX; + + if (!_regulator_is_enabled(c_rdevs[i])) + continue; + + ret = regulator_check_consumers(c_rdevs[i], + &tmp_min, + &tmp_max, PM_SUSPEND_ON); + if (ret < 0) + goto out; + + if (tmp_min > highest_min_uV) + highest_min_uV = tmp_min; + } + + /* + * Let target_uV be equal to the desired one if possible. + * If not, set it to minimum voltage, allowed by other coupled + * regulators. + */ + target_uV = max(desired_min_uV, highest_min_uV - max_spread); + + /* + * Find min and max voltages, which currently aren't + * violating max_spread + */ + for (i = 0; i < n_coupled; i++) { + int tmp_act; + + /* + * Don't check the regulator, which is about + * to change voltage + */ + if (c_rdevs[i] == rdev) + continue; + if (!_regulator_is_enabled(c_rdevs[i])) + continue; + + tmp_act = _regulator_get_voltage(c_rdevs[i]); + if (tmp_act < 0) { + ret = tmp_act; + goto out; + } + + if (tmp_act < min_current_uV) + min_current_uV = tmp_act; + + if (tmp_act > max_current_uV) + max_current_uV = tmp_act; + } + + /* There aren't any other regulators enabled */ + if (max_current_uV == 0) { + possible_uV = target_uV; + } else { + /* + * Correct target voltage, so as it currently isn't + * violating max_spread + */ + possible_uV = max(target_uV, max_current_uV - max_spread); + possible_uV = min(possible_uV, min_current_uV + max_spread); + } + + if (possible_uV > desired_max_uV) { + ret = -EINVAL; + goto out; + } + ret = possible_uV; + +out: + return ret; +} + +static int regulator_balance_voltage(struct regulator_dev *rdev, + suspend_state_t state) +{ + struct regulator_dev **c_rdevs; + struct regulator_dev *best_rdev; + struct coupling_desc *c_desc = &rdev->coupling_desc; + int n_coupled; + int i, best_delta, best_uV, ret = 1; + + c_rdevs = c_desc->coupled_rdevs; + n_coupled = c_desc->n_coupled; + + /* + * if system is in a state other than PM_SUSPEND_ON, don't check + * other coupled regulators + */ + if (state != PM_SUSPEND_ON) + n_coupled = 1; + + /* + * Find the best possible voltage change on each loop. Leave the loop + * if there isn't any possible change. + */ + while (1) { + best_delta = 0; + best_uV = 0; + best_rdev = NULL; + + /* + * Find highest difference between optimal voltage + * and current voltage. + */ + for (i = 0; i < n_coupled; i++) { + /* + * optimal_uV is the best voltage that can be set for + * i-th regulator at the moment without violating + * max_spread constraint in order to balance + * the coupled voltages. + */ + int optimal_uV, current_uV; + + optimal_uV = regulator_get_optimal_voltage(c_rdevs[i]); + if (optimal_uV < 0) { + ret = optimal_uV; + goto out; + } + + current_uV = _regulator_get_voltage(c_rdevs[i]); + if (current_uV < 0) { + ret = optimal_uV; + goto out; + } + + if (abs(best_delta) < abs(optimal_uV - current_uV)) { + best_delta = optimal_uV - current_uV; + best_rdev = c_rdevs[i]; + best_uV = optimal_uV; + } + } + + /* Nothing to change, return successfully */ + if (!best_rdev) { + ret = 0; + goto out; + } + + /* + * Lock just the supply regulators, as the regulator itself + * is already locked by regulator_lock_coupled(). + */ + if (best_rdev->supply) + regulator_lock_supply(best_rdev->supply->rdev); + + ret = regulator_set_voltage_rdev(best_rdev, best_uV, + best_uV, state); + if (best_rdev->supply) + regulator_unlock_supply(best_rdev->supply->rdev); + + if (ret < 0) + goto out; + } + +out: + return ret; +} + /** * regulator_set_voltage - set regulator output voltage * @regulator: regulator source -- 2.17.0 -- 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
