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regulator: core: Reduce busy-wait looping
Keep busy-wait looping to a minimum while waiting for a regulator to ramp-up to the target voltage. This follows the guidelines set forth in Documentation/timers/timers-howto.txt and assumes that regulators are never enabled in atomic context. Signed-off-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Mark Brown <broonie@linaro.org>
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1 changed files with 33 additions and 5 deletions
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@ -1740,11 +1740,39 @@ static int _regulator_do_enable(struct regulator_dev *rdev)
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* together. */
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trace_regulator_enable_delay(rdev_get_name(rdev));
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if (delay >= 1000) {
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mdelay(delay / 1000);
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udelay(delay % 1000);
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} else if (delay) {
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udelay(delay);
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/*
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* Delay for the requested amount of time as per the guidelines in:
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*
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* Documentation/timers/timers-howto.txt
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*
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* The assumption here is that regulators will never be enabled in
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* atomic context and therefore sleeping functions can be used.
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*/
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if (delay) {
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unsigned int ms = delay / 1000;
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unsigned int us = delay % 1000;
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if (ms > 0) {
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/*
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* For small enough values, handle super-millisecond
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* delays in the usleep_range() call below.
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*/
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if (ms < 20)
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us += ms * 1000;
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else
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msleep(ms);
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}
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/*
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* Give the scheduler some room to coalesce with any other
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* wakeup sources. For delays shorter than 10 us, don't even
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* bother setting up high-resolution timers and just busy-
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* loop.
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*/
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if (us >= 10)
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usleep_range(us, us + 100);
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else
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udelay(us);
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}
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trace_regulator_enable_complete(rdev_get_name(rdev));
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