[4.2.y-ckt stable] Patch "hwmon: (gpio-fan) Remove un-necessary speed_index lookup for thermal hook" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    hwmon: (gpio-fan) Remove un-necessary speed_index lookup for thermal hook

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt5.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From f95af21d46d4b20fe8c670eb474ef3b6dd423fa0 Mon Sep 17 00:00:00 2001
From: Nishanth Menon <nm at ti.com>
Date: Fri, 19 Feb 2016 18:09:51 -0600
Subject: hwmon: (gpio-fan) Remove un-necessary speed_index lookup for thermal
 hook

commit 000e0949148382c4962489593a2f05504c2a6771 upstream.

Thermal hook gpio_fan_get_cur_state is only interested in knowing
the current speed index that was setup in the system, this is
already available as part of fan_data->speed_index which is always
set by set_fan_speed. Using get_fan_speed_index is useful when we
have no idea about the fan speed configuration (for example during
fan_ctrl_init).

When thermal framework invokes
gpio_fan_get_cur_state=>get_fan_speed_index via gpio_fan_get_cur_state
especially in a polled configuration for thermal governor, we
basically hog the i2c interface to the extent that other functions
fail to get any traffic out :(.

Instead, just provide the last state set in the driver - since the gpio
fan driver is responsible for the fan state immaterial of override, the
fan_data->speed_index should accurately reflect the state.

Fixes: b5cf88e46bad ("(gpio-fan): Add thermal control hooks")
Reported-by: Tony Lindgren <tony at atomide.com>
Cc: Guenter Roeck <linux at roeck-us.net>
Cc: Eduardo Valentin <edubezval at gmail.com>
Signed-off-by: Nishanth Menon <nm at ti.com>
Signed-off-by: Guenter Roeck <linux at roeck-us.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/hwmon/gpio-fan.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/hwmon/gpio-fan.c b/drivers/hwmon/gpio-fan.c
index a3dae6d..83ea8c8 100644
--- a/drivers/hwmon/gpio-fan.c
+++ b/drivers/hwmon/gpio-fan.c
@@ -406,16 +406,11 @@ static int gpio_fan_get_cur_state(struct thermal_cooling_device *cdev,
 				  unsigned long *state)
 {
 	struct gpio_fan_data *fan_data = cdev->devdata;
-	int r;

 	if (!fan_data)
 		return -EINVAL;

-	r = get_fan_speed_index(fan_data);
-	if (r < 0)
-		return r;
-
-	*state = r;
+	*state = fan_data->speed_index;
 	return 0;
 }

--
2.7.0