linux-kernel - [PATCH] hwmon: fix corsair-psu fan rpm calculation

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Date:   Fri, 13 Nov 2020 13:19:54 +0100
From:   Wilken Gottwalt <wilken.gottwalt@...teo.net>
To:     linux-kernel@...r.kernel.org
Cc:     Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Jonathan Corbet <corbet@....net>, linux-hwmon@...r.kernel.org
Subject: [PATCH] hwmon: fix corsair-psu fan rpm calculation

The correct fan rpm value is also a LINEAR11 value but without a factor.
Verified by using the fan test button on the psu to let the fan spin up
to maximum for some seconds.

Fixes: 933222c98445 ("hwmon: (corsair-psu) fix unintentional sign extension issue")
Signed-off-by: Wilken Gottwalt <wilken.gottwalt@...teo.net>
---
 drivers/hwmon/corsair-psu.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/hwmon/corsair-psu.c b/drivers/hwmon/corsair-psu.c
index 5d19a888231a..99494056f4bd 100644
--- a/drivers/hwmon/corsair-psu.c
+++ b/drivers/hwmon/corsair-psu.c
@@ -252,12 +252,7 @@ static int corsairpsu_get_value(struct corsairpsu_data *priv, u8 cmd, u8 rail, l
 		*val = corsairpsu_linear11_to_int(tmp & 0xFFFF) * 1000;
 		break;
 	case PSU_CMD_FAN:
-		/*
-		 * this value is best guess, so the calculated value could be wrong, it is hard
-		 * to ge the fan to spin in these semi-passive power supplies, which need a
-		 * quite high load to do so
-		 */
-		*val = ((tmp & 0xFF) << 8) + ((tmp >> 8) & 0xFF);
+		*val = corsairpsu_linear11_to_int(tmp & 0xFFFF);
 		break;
 	case PSU_CMD_RAIL_WATTS:
 	case PSU_CMD_TOTAL_WATTS:
-- 
2.29.2