linux-kernel - [PATCH V2 1/4] opp: Enable resources again if they were disabled earlier

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Message-Id: <c6bba235a9a6fd777255bb4f1d16492fdcabc847.1597292833.git.viresh.kumar@linaro.org>
Date:   Thu, 13 Aug 2020 09:58:58 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rajendra Nayak <rnayak@...eaurora.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>, mka@...omium.org,
        sibis@...eaurora.org, "v5 . 3+" <stable@...r.kernel.org>,
        Sajida Bhanu <sbhanu@...eaurora.org>,
        Stephen Boyd <swboyd@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH V2 1/4] opp: Enable resources again if they were disabled earlier

From: Rajendra Nayak <rnayak@...eaurora.org>

dev_pm_opp_set_rate() can now be called with freq = 0 in order
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.

Cc: v5.3+ <stable@...r.kernel.org> # v5.3+
Fixes: cd7ea582 ("opp: Make dev_pm_opp_set_rate() handle freq = 0 to drop performance votes")
Reported-by: Sajida Bhanu <sbhanu@...eaurora.org>
Reviewed-by: Sibi Sankar <sibis@...eaurora.org>
Reported-by: Matthias Kaehlcke <mka@...omium.org>
Tested-by: Matthias Kaehlcke <mka@...omium.org>
Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
[ Viresh: Don't skip clk_set_rate() and massaged changelog ]
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
Hi Rajendra,

I wasn't able to test this stuff, please give it a try. I have
simplified your patch and cleaned up a bunch of stuff as well.

 drivers/opp/core.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index bdb028c7793d..9668ea04cc80 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -934,10 +934,13 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 
 	/* Return early if nothing to do */
 	if (old_freq == freq) {
-		dev_dbg(dev, "%s: old/new frequencies (%lu Hz) are same, nothing to do\n",
-			__func__, freq);
-		ret = 0;
-		goto put_opp_table;
+		if (!opp_table->required_opp_tables && !opp_table->regulators &&
+		    !opp_table->paths) {
+			dev_dbg(dev, "%s: old/new frequencies (%lu Hz) are same, nothing to do\n",
+				__func__, freq);
+			ret = 0;
+			goto put_opp_table;
+		}
 	}
 
 	/*
-- 
2.14.1