regulator: core: Use ktime_get_boottime() to determine how long a regulator was off

For regulators with 'off-on-delay-us' the regulator framework currently
uses ktime_get() to determine how long the regulator has been off
before re-enabling it (after a delay if needed). A problem with using
ktime_get() is that it doesn't account for the time the system is
suspended. As a result a regulator with a longer 'off-on-delay' (e.g.
500ms) that was switched off during suspend might still incurr in a
delay on resume before it is re-enabled, even though the regulator
might have been off for hours. ktime_get_boottime() accounts for
suspend time, use it instead of ktime_get().

Fixes: a8ce7bd8 ("regulator: core: Fix off_on_delay handling")
Cc: stable@vger.kernel.org    # 5.13+
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20230223003301.v2.1.I9719661b8eb0a73b8c416f9c26cf5bd8c0563f99@changeidSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1584,7 +1584,7 @@ static int set_machine_constraints(struct regulator_dev *rdev)
 	}
 
 	if (rdev->desc->off_on_delay)
-		rdev->last_off = ktime_get();
+		rdev->last_off = ktime_get_boottime();
 
 	/* If the constraints say the regulator should be on at this point
 	 * and we have control then make sure it is enabled.
@@ -2673,7 +2673,7 @@ static int _regulator_do_enable(struct regulator_dev *rdev)
 		 * this regulator was disabled.
 		 */
 		ktime_t end = ktime_add_us(rdev->last_off, rdev->desc->off_on_delay);
-		s64 remaining = ktime_us_delta(end, ktime_get());
+		s64 remaining = ktime_us_delta(end, ktime_get_boottime());
 
 		if (remaining > 0)
 			_regulator_delay_helper(remaining);
@@ -2912,7 +2912,7 @@ static int _regulator_do_disable(struct regulator_dev *rdev)
 	}
 
 	if (rdev->desc->off_on_delay)
-		rdev->last_off = ktime_get();
+		rdev->last_off = ktime_get_boottime();
 
 	trace_regulator_disable_complete(rdev_get_name(rdev));