From 062920d2464715ef5cbba52a8573ba12cc882b8f Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Wed, 20 Apr 2022 14:22:13 -0700 Subject: [PATCH] regulator: core: Sleep (not delay) in set_voltage() These delays can be relatively large (e.g., hundreds of microseconds to several milliseconds on RK3399 Gru systems). Per Documentation/timers/timers-howto.rst, that should usually use a sleeping delay. Let's use the existing regulator delay helper to handle both large and small delays appropriately. This avoids burning a bunch of CPU time and hurting scheduling latencies when hitting regulators a lot (e.g., during cpufreq). The sleep vs. delay issue choice has been made differently over time -- early versions of RK3399 Gru PWM-regulator support used usleep_range() in pwm-regulator.c. More of this got moved into the regulator core, in commits like: 73e705bf81ce regulator: core: Add set_voltage_time op At the same time, the sleep turned into a delay. It's OK to sleep in _regulator_do_set_voltage(), as we aren't in an atomic context. (All our callers grab various mutexes already.) I avoid using fsleep() because it uses a usleep_range() of [N to N*2], and usleep_range() very commonly biases to the high end of the range. We don't want to double the expected delay, especially for long delays. Signed-off-by: Brian Norris Reviewed-by: Matthias Kaehlcke Link: https://lore.kernel.org/r/20220420141511.v2.2.If0fc61a894f537b052ca41572aff098cf8e7e673@changeid Signed-off-by: Mark Brown --- drivers/regulator/core.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index d9c7db1..ce3786e 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -3566,12 +3566,7 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev, } /* Insert any necessary delays */ - if (delay >= 1000) { - mdelay(delay / 1000); - udelay(delay % 1000); - } else if (delay) { - udelay(delay); - } + _regulator_delay_helper(delay); if (best_val >= 0) { unsigned long data = best_val; -- 2.7.4