Re: [PATCH V4 3/3] Thermal: do thermal zone update after a cooling device registered

[Eduardo Valentin <edubezval@gmail.com>]

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Hello Rui,

On Tue, Apr 07, 2015 at 10:24:36AM +0800, Zhang Rui wrote:
> When a new cooling device is registered, we need to update the
> thermal zone to set the new registered cooling device to a proper
> state.
> 
> This fixes a problem that the system is cool, while the fan devices are left
> running on full speed after boot, if fan device is registered after
> thermal zone device.
> 
> CC: <stable@vger.kernel.org> #3.18+
> Reference:https://bugzilla.kernel.org/show_bug.cgi?id=92431
> Tested-by: Manuel Krause <manuelkrause@netscape.net>
> Tested-by: szegad <szegadlo@poczta.onet.pl>
> Tested-by: prash <prash.n.rao@gmail.com>
> Tested-by: amish <ammdispose-arch@yahoo.com>
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> ---
>  drivers/thermal/thermal_core.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 875a9bb..e37042c 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1140,6 +1140,7 @@ __thermal_cooling_device_register(struct device_node *np,
>  				  const struct thermal_cooling_device_ops *ops)
>  {
>  	struct thermal_cooling_device *cdev;
> +	struct thermal_instance *pos, *next;
>  	int result;
>  
>  	if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> @@ -1184,6 +1185,15 @@ __thermal_cooling_device_register(struct device_node *np,
>  	/* Update binding information for 'this' new cdev */
>  	bind_cdev(cdev);
>  
> +	list_for_each_entry_safe(pos, next, &cdev->thermal_instances, cdev_node) {
> +			if (next->cdev_node.next == &cdev->thermal_instances) {
> +				thermal_zone_device_update(next->tz);
> +				break;
> +			}
> +			if (pos->tz != next->tz)
> +				thermal_zone_device_update(pos->tz);
> +	}

Maybe the reasoning for not calling only when initialized == false is
because at this point all instances are initialized == false. 

Then why not moving this thermal_zone_device_update(tz) to the
thermal_zone_bind_cooling_device(), where we create the
thermal_instance?

> +

Besides, Can you please elaborate more on why we need to specifically call
thermal_zone_device_update(tz) here and not simply wait until next
tz->poll_queue work is called?

Any particular reason for the problem not be solved byt the call
of thermal_zone_device_update(tz) from the poll_queue of each tz?



>  	return cdev;
>  }
>  
> -- 
> 1.9.1
> 
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