linux-kernel - [PATCH] opp: core: Revert "add regulators enable and disable"

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Date:   Thu, 17 Oct 2019 12:27:58 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Dmitry Osipenko <digetx@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Kamil Konieczny <k.konieczny@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>
Subject: [PATCH] opp: core: Revert "add regulators enable and disable"

All the drivers, which use the OPP framework control regulators, which
are already enabled. Typically those regulators are also system critical,
due to providing power to CPU core or system buses. It turned out that
there are cases, where calling regulator_enable() on such boot-enabled
regulator has side-effects and might change its initial voltage due to
performing initial voltage balancing without all restrictions from the
consumers. Until this issue becomes finally solved in regulator core,
avoid calling regulator_enable()/disable() from the OPP framework.

This reverts commit 7f93ff73f7c8c8bfa6be33bcc16470b0b44682aa.

Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
---
This is a follow-up from the following discussion:
https://lkml.org/lkml/2019/10/9/541
---
 drivers/opp/core.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 3b7ffd0234e9..9ff0538ee83a 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1626,12 +1626,6 @@ struct opp_table *dev_pm_opp_set_regulators(struct device *dev,
 			goto free_regulators;
 		}
 
-		ret = regulator_enable(reg);
-		if (ret < 0) {
-			regulator_put(reg);
-			goto free_regulators;
-		}
-
 		opp_table->regulators[i] = reg;
 	}
 
@@ -1645,10 +1639,8 @@ struct opp_table *dev_pm_opp_set_regulators(struct device *dev,
 	return opp_table;
 
 free_regulators:
-	while (i--) {
-		regulator_disable(opp_table->regulators[i]);
-		regulator_put(opp_table->regulators[i]);
-	}
+	while (i != 0)
+		regulator_put(opp_table->regulators[--i]);
 
 	kfree(opp_table->regulators);
 	opp_table->regulators = NULL;
@@ -1674,10 +1666,8 @@ void dev_pm_opp_put_regulators(struct opp_table *opp_table)
 	/* Make sure there are no concurrent readers while updating opp_table */
 	WARN_ON(!list_empty(&opp_table->opp_list));
 
-	for (i = opp_table->regulator_count - 1; i >= 0; i--) {
-		regulator_disable(opp_table->regulators[i]);
+	for (i = opp_table->regulator_count - 1; i >= 0; i--)
 		regulator_put(opp_table->regulators[i]);
-	}
 
 	_free_set_opp_data(opp_table);
 
-- 
2.17.1