linux-kernel - [PATCH] thermal/drivers/cpufreq_cooling: Fix wrong frequency converted from power

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Date:   Fri, 19 Jun 2020 17:08:25 +0800
From:   Finley Xiao <finley.xiao@...k-chips.com>
To:     heiko@...ech.de, amit.kachhap@...il.com, daniel.lezcano@...aro.org,
        viresh.kumar@...aro.org, javi.merino@...nel.org,
        rui.zhang@...el.com, amit.kucheria@...durent.com
Cc:     linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, stable@...r.kernel.org,
        huangtao@...k-chips.com, tony.xie@...k-chips.com,
        cl@...k-chips.com, Finley Xiao <finley.xiao@...k-chips.com>
Subject: [PATCH] thermal/drivers/cpufreq_cooling: Fix wrong frequency converted from power

The function cpu_power_to_freq is used to find a frequency and set the
cooling device to consume at most the power to be converted. For example,
if the power to be converted is 80mW, and the em table is as follow.
struct em_cap_state table[] = {
	/* KHz     mW */
	{ 1008000, 36, 0 },
	{ 1200000, 49, 0 },
	{ 1296000, 59, 0 },
	{ 1416000, 72, 0 },
	{ 1512000, 86, 0 },
};
The target frequency should be 1416000KHz, not 1512000KHz.

Fixes: 349d39dc5739 ("thermal: cpu_cooling: merge frequency and power tables")
Cc: <stable@...r.kernel.org> # v4.13+
Signed-off-by: Finley Xiao <finley.xiao@...k-chips.com>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/thermal/cpufreq_cooling.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/thermal/cpufreq_cooling.c b/drivers/thermal/cpufreq_cooling.c
index 9e124020519f..6c0e1b053126 100644
--- a/drivers/thermal/cpufreq_cooling.c
+++ b/drivers/thermal/cpufreq_cooling.c
@@ -123,12 +123,12 @@ static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
 {
 	int i;
 
-	for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
-		if (power > cpufreq_cdev->em->table[i].power)
+	for (i = cpufreq_cdev->max_level; i >= 0; i--) {
+		if (power >= cpufreq_cdev->em->table[i].power)
 			break;
 	}
 
-	return cpufreq_cdev->em->table[i + 1].frequency;
+	return cpufreq_cdev->em->table[i].frequency;
 }
 
 /**
-- 
2.11.0