linux-kernel - [PATCH 2/6] devfreq: refactor set

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Message-Id: <1542823301-23563-3-git-send-email-l.luba@partner.samsung.com>
Date:   Wed, 21 Nov 2018 19:01:37 +0100
From:   Lukasz Luba <l.luba@...tner.samsung.com>
To:     linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org
Cc:     tjakobi@...h.uni-bielefeld.de, myungjoo.ham@...sung.com,
        kyungmin.park@...sung.com, cw00.choi@...sung.com,
        rjw@...ysocki.net, len.brown@...el.com, pavel@....cz,
        gregkh@...uxfoundation.org, keescook@...omium.org,
        anton@...msg.org, ccross@...roid.com, tony.luck@...el.com,
        robh+dt@...nel.org, mark.rutland@....com, kgene@...nel.org,
        krzk@...nel.org, m.szyprowski@...sung.com,
        b.zolnierkie@...sung.com, Lukasz Luba <l.luba@...tner.samsung.com>
Subject: [PATCH 2/6] devfreq: refactor set_target frequency function

The refactoring is needed for the new client in devfreq: suspend.
To avoid code duplication, move it to the new local function
devfreq_set_target.

The patch draws on Tobias Jakobi's work posted ~2 years ago, who tried to
solve issue with devfreq device's frequency during suspend/resume.
During the discussion on LKML some corner cases and comments appeared
related to the design. This patch address them keeping in mind suggestions
from Chanwoo Choi.

Suggested-by: Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>
Suggested-by: Chanwoo Choi <cw00.choi@...sung.com>
Signed-off-by: Lukasz Luba <l.luba@...tner.samsung.com>
---
 drivers/devfreq/devfreq.c | 62 ++++++++++++++++++++++++++++-------------------
 1 file changed, 37 insertions(+), 25 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index e20e7e4..cf9c643 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -285,6 +285,42 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
 	return 0;
 }
 
+static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
+			      unsigned long *prev_freq, u32 flags)
+{
+	struct devfreq_freqs freqs;
+	unsigned long cur_freq;
+	int err = 0;
+
+	if (devfreq->profile->get_cur_freq)
+		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
+	else
+		cur_freq = devfreq->previous_freq;
+
+	freqs.old = cur_freq;
+	freqs.new = new_freq;
+	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
+
+	err = devfreq->profile->target(devfreq->dev.parent, &new_freq, flags);
+	if (err) {
+		freqs.new = cur_freq;
+		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
+		return err;
+	}
+
+	freqs.new = new_freq;
+	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
+
+	if (devfreq_update_status(devfreq, new_freq))
+		dev_err(&devfreq->dev,
+			"Couldn't update frequency transition information.\n");
+
+	devfreq->previous_freq = new_freq;
+	*prev_freq = cur_freq;
+
+	return err;
+}
+
 /* Load monitoring helper functions for governors use */
 
 /**
@@ -296,7 +332,6 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
  */
 int update_devfreq(struct devfreq *devfreq)
 {
-	struct devfreq_freqs freqs;
 	unsigned long freq, cur_freq, min_freq, max_freq;
 	int err = 0;
 	u32 flags = 0;
@@ -333,31 +368,8 @@ int update_devfreq(struct devfreq *devfreq)
 		flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 	}
 
-	if (devfreq->profile->get_cur_freq)
-		devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
-	else
-		cur_freq = devfreq->previous_freq;
-
-	freqs.old = cur_freq;
-	freqs.new = freq;
-	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
+	return devfreq_set_target(devfreq, freq, &cur_freq, flags);
 
-	err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
-	if (err) {
-		freqs.new = cur_freq;
-		devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
-		return err;
-	}
-
-	freqs.new = freq;
-	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
-
-	if (devfreq_update_status(devfreq, freq))
-		dev_err(&devfreq->dev,
-			"Couldn't update frequency transition information.\n");
-
-	devfreq->previous_freq = freq;
-	return err;
 }
 EXPORT_SYMBOL(update_devfreq);
 
-- 
2.7.4