Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Brian Norris <> | Subject | [PATCH v2 2/2] regulator: core: Sleep (not delay) in set_voltage() | Date | Wed, 20 Apr 2022 14:22:13 -0700 |
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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 <briannorris@chromium.org> Reviewed-by: Matthias Kaehlcke <mka@chromium.org> ---
Changes in v2: * Add Matthias's "Reviewed-by" * Use regulator helper instead of fsleep() * Reorder patch 1&2
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 8b188e56fd0b..0279ff687e1d 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -3548,12 +3548,7 @@ 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; -- 2.36.0.rc0.470.gd361397f0d-goog
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