Patch "hwmon: (it87) Do not overwrite bit 2..6 of pwm control registers" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    hwmon: (it87) Do not overwrite bit 2..6 of pwm control registers

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     hwmon-it87-do-not-overwrite-bit-2..6-of-pwm-control-registers.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 4c7b8ca1ae5ed9e27014732c8a918ba11a86cf09 Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@roeck-us.net>
Date: Wed, 8 Feb 2017 14:07:42 -0800
Subject: hwmon: (it87) Do not overwrite bit 2..6 of pwm control registers

From: Guenter Roeck <linux@roeck-us.net>

commit 4c7b8ca1ae5ed9e27014732c8a918ba11a86cf09 upstream.

In IT8620E, after setting pwm control to manual, it was observed that
pwm values for fan 4..6 have reversed results (writing 0 results in fans
running at full speed, writing 255 results in fans turned off).

With the new PWM control, pwm polarity for pwm control 4..6 is specified
in its pwm control registers. Those registers are overwritten when setting
the pwm mode or the temperature mapping. Do not touch bit 2..6 of pwm
control registers on register writes to fix the problem.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hwmon/it87.c |   37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -1300,25 +1300,35 @@ static ssize_t set_pwm_enable(struct dev
 			it87_write_value(data, IT87_REG_FAN_MAIN_CTRL,
 					 data->fan_main_ctrl);
 		} else {
+			u8 ctrl;
+
 			/* No on/off mode, set maximum pwm value */
 			data->pwm_duty[nr] = pwm_to_reg(data, 0xff);
 			it87_write_value(data, IT87_REG_PWM_DUTY[nr],
 					 data->pwm_duty[nr]);
 			/* and set manual mode */
-			data->pwm_ctrl[nr] = has_newer_autopwm(data) ?
-					     data->pwm_temp_map[nr] :
-					     data->pwm_duty[nr];
-			it87_write_value(data, IT87_REG_PWM[nr],
-					 data->pwm_ctrl[nr]);
+			if (has_newer_autopwm(data)) {
+				ctrl = (data->pwm_ctrl[nr] & 0x7c) |
+					data->pwm_temp_map[nr];
+			} else {
+				ctrl = data->pwm_duty[nr];
+			}
+			data->pwm_ctrl[nr] = ctrl;
+			it87_write_value(data, IT87_REG_PWM[nr], ctrl);
 		}
 	} else {
-		if (val == 1)				/* Manual mode */
-			data->pwm_ctrl[nr] = has_newer_autopwm(data) ?
-					     data->pwm_temp_map[nr] :
-					     data->pwm_duty[nr];
-		else					/* Automatic mode */
-			data->pwm_ctrl[nr] = 0x80 | data->pwm_temp_map[nr];
-		it87_write_value(data, IT87_REG_PWM[nr], data->pwm_ctrl[nr]);
+		u8 ctrl;
+
+		if (has_newer_autopwm(data)) {
+			ctrl = (data->pwm_ctrl[nr] & 0x7c) |
+				data->pwm_temp_map[nr];
+			if (val != 1)
+				ctrl |= 0x80;
+		} else {
+			ctrl = (val == 1 ? data->pwm_duty[nr] : 0x80);
+		}
+		data->pwm_ctrl[nr] = ctrl;
+		it87_write_value(data, IT87_REG_PWM[nr], ctrl);
 
 		if (data->type != it8603 && nr < 3) {
 			/* set SmartGuardian mode */
@@ -1462,7 +1472,8 @@ static ssize_t set_pwm_temp_map(struct d
 	 * otherwise, just store it for later use.
 	 */
 	if (data->pwm_ctrl[nr] & 0x80) {
-		data->pwm_ctrl[nr] = 0x80 | data->pwm_temp_map[nr];
+		data->pwm_ctrl[nr] = (data->pwm_ctrl[nr] & 0xfc) |
+						data->pwm_temp_map[nr];
 		it87_write_value(data, IT87_REG_PWM[nr], data->pwm_ctrl[nr]);
 	}
 	mutex_unlock(&data->update_lock);


Patches currently in stable-queue which might be from linux@roeck-us.net are

queue-4.9/hwmon-it87-ensure-that-pwm-control-cache-is-current-before-updating-values.patch
queue-4.9/hwmon-it87-do-not-overwrite-bit-2..6-of-pwm-control-registers.patch