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Commit 5df529d4 authored by Thierry Reding's avatar Thierry Reding Committed by Mark Brown
Browse files

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: default avatarThierry Reding <treding@nvidia.com>
Signed-off-by: default avatarMark Brown <broonie@linaro.org>
parent 043c998f

drivers/regulator/core.c

+33 −5
Original line number Diff line number Diff line
@@ -1740,11 +1740,39 @@ static int _regulator_do_enable(struct regulator_dev *rdev) 
	 * together.  */

	trace_regulator_enable_delay(rdev_get_name(rdev));



	if (delay >= 1000) {

		mdelay(delay / 1000);

		udelay(delay % 1000);

	} else if (delay) {

		udelay(delay);

	/*

	 * Delay for the requested amount of time as per the guidelines in:

	 *

	 *     Documentation/timers/timers-howto.txt

	 *

	 * The assumption here is that regulators will never be enabled in

	 * atomic context and therefore sleeping functions can be used.

	 */

	if (delay) {

		unsigned int ms = delay / 1000;

		unsigned int us = delay % 1000;



		if (ms > 0) {

			/*

			 * For small enough values, handle super-millisecond

			 * delays in the usleep_range() call below.

			 */

			if (ms < 20)

				us += ms * 1000;

			else

				msleep(ms);

		}



		/*

		 * Give the scheduler some room to coalesce with any other

		 * wakeup sources. For delays shorter than 10 us, don't even

		 * bother setting up high-resolution timers and just busy-

		 * loop.

		 */

		if (us >= 10)

			usleep_range(us, us + 100);

		else

			udelay(us);

	}



	trace_regulator_enable_complete(rdev_get_name(rdev));