On 02/19/2016 04:09 PM, Nishanth Menon wrote:
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@xxxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Eduardo Valentin <edubezval@xxxxxxxxx>
Signed-off-by: Nishanth Menon <nm@xxxxxx>
---
Applied.
Thanks,
Guenter
Test logs from linus master v4.5-rc4-137-g23300f657594
Without fix: http://paste.ubuntu.org.cn/3948618
With Fix: http://paste.ubuntu.org.cn/3948617
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 82de3deeb18a..685568b1236d 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;
}
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