linux-kernel - [PATCH] opp: Fix dev_pm_opp_set

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Date:   Mon, 10 Aug 2020 12:36:19 +0530
From:   Rajendra Nayak <rnayak@...eaurora.org>
To:     vireshk@...nel.org, nm@...com, sboyd@...nel.org,
        viresh.kumar@...aro.org
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        Rajendra Nayak <rnayak@...eaurora.org>
Subject: [PATCH] opp: Fix dev_pm_opp_set_rate() to not return early

dev_pm_opp_set_rate() can now be called with freq = 0 inorder
to either drop performance or bandwidth votes or to disable
regulators on platforms which support them.
In such cases, a subsequent call to dev_pm_opp_set_rate() with
the same frequency ends up returning early because 'old_freq == freq'
Instead make it fall through and put back the dropped performance
and bandwidth votes and/or enable back the regulators.

Fixes: cd7ea582 ("opp: Make dev_pm_opp_set_rate() handle freq = 0 to drop performance votes")
Reported-by: Sajida Bhanu <sbhanu@...eaurora.org>
Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
---
 drivers/opp/core.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 0c8c74a..a994f30 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -901,6 +901,9 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 
 	/* Return early if nothing to do */
 	if (old_freq == freq) {
+		if (opp_table->required_opp_tables || opp_table->regulators ||
+		    opp_table->paths)
+			goto skip_clk_only;
 		dev_dbg(dev, "%s: old/new frequencies (%lu Hz) are same, nothing to do\n",
 			__func__, freq);
 		ret = 0;
@@ -919,6 +922,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 		goto put_opp_table;
 	}
 
+skip_clk_only:
 	temp_freq = old_freq;
 	old_opp = _find_freq_ceil(opp_table, &temp_freq);
 	if (IS_ERR(old_opp)) {
@@ -954,8 +958,10 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 						 IS_ERR(old_opp) ? NULL : old_opp->supplies,
 						 opp->supplies);
 	} else {
+		ret = 0;
 		/* Only frequency scaling */
-		ret = _generic_set_opp_clk_only(dev, clk, freq);
+		if (freq != old_freq)
+			ret = _generic_set_opp_clk_only(dev, clk, freq);
 	}
 
 	/* Scaling down? Configure required OPPs after frequency */
-- 
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