linux-kernel - [PATCH 3.19 075/123] regulator: Only enable disabled regulators on resume

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Message-Id: <20150324154427.410179592@linuxfoundation.org>
Date:	Tue, 24 Mar 2015 16:46:24 +0100
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	Mark Brown <broonie@...nel.org>
Subject: [PATCH 3.19 075/123] regulator: Only enable disabled regulators on resume

3.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Javier Martinez Canillas <javier.martinez@...labora.co.uk>

commit 0548bf4f5ad6fc3bd93c4940fa48078b34609682 upstream.

The _regulator_do_enable() call ought to be a no-op when called on an
already-enabled regulator.  However, as an optimization
_regulator_enable() doesn't call _regulator_do_enable() on an already
enabled regulator.  That means we never test the case of calling
_regulator_do_enable() during normal usage and there may be hidden
bugs or warnings.  We have seen warnings issued by the tps65090 driver
and bugs when using the GPIO enable pin.

Let's match the same optimization that _regulator_enable() in
regulator_suspend_finish().  That may speed up suspend/resume and also
avoids exposing hidden bugs.

[Use much clearer commit message from Doug Anderson]

Signed-off-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/regulator/core.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -3856,9 +3856,11 @@ int regulator_suspend_finish(void)
 	list_for_each_entry(rdev, &regulator_list, list) {
 		mutex_lock(&rdev->mutex);
 		if (rdev->use_count > 0  || rdev->constraints->always_on) {
-			error = _regulator_do_enable(rdev);
-			if (error)
-				ret = error;
+			if (!_regulator_is_enabled(rdev)) {
+				error = _regulator_do_enable(rdev);
+				if (error)
+					ret = error;
+			}
 		} else {
 			if (!have_full_constraints())
 				goto unlock;


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