Re: [RFC][PATCH] thermal: add sysfs_notify on some attributes

[Pandruvada, Srinivas]

On Tue, 2016-02-23 at 20:11 -0800, Srikar Srimath Tirumala wrote:
> Add a sysfs_notify on thermal_zone*/temp and cooling_device*/
> cur_state whenever a passive or critical trip is triggered.
> 
> This change allows usermode apps to register itself to get notified,
> when certain thermal conditions occur and reduce their workload.
> This workload throttling can reduce\prevent throttling of hardware
> clocks while allowing some other critical apps to run longer
> reliably.
> Signed-off-by: Srikar Srimath Tirumala <srikars@xxxxxxxxxx>
> ---
> Âdrivers/thermal/thermal_core.c | 3 +++
> Â1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/thermal/thermal_core.c
> b/drivers/thermal/thermal_core.c
> index a0a8fd1..d8d257d 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -567,6 +567,8 @@ void thermal_zone_device_update(struct
> thermal_zone_device *tz)
> Â
> Â	for (count = 0; count < tz->trips; count++)
> Â		handle_thermal_trip(tz, count);
> +
> +	sysfs_notify(&tz->device.kobj, NULL, "temp");
When user space governor is used this will result in two notifications
to user space.
Also you want when a trip is violated. For some driver there will be
too many calls from irq thread, so you may want in handle_thermal_trip
when a trip is violated.

Thanks,
Srinivas
> Â}
> ÂEXPORT_SYMBOL_GPL(thermal_zone_device_update);
> Â
> @@ -1638,6 +1640,7 @@ void thermal_cdev_update(struct
> thermal_cooling_device *cdev)
> Â	cdev->updated = true;
> Â	trace_cdev_update(cdev, target);
> Â	dev_dbg(&cdev->device, "set to state %lu\n", target);
> +	sysfs_notify(&cdev->device.kobj, NULL, "cur_state");
> Â}
> ÂEXPORT_SYMBOL(thermal_cdev_update);
> Â