linux-kernel - Re: [PATCH 3/3][v2] Thermal: do thermal zone update after a cooling device registered

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Date:	Wed, 28 Oct 2015 10:39:47 +0000
From:	Javi Merino <javi.merino@....com>
To:	Chen Yu <yu.c.chen@...el.com>
Cc:	rui.zhang@...el.com, edubezval@...il.com, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 3/3][v2] Thermal: do thermal zone update after a cooling
 device registered

Hi Yu,

One minor nit below.  Other than that you can add my

Reviewed-by: Javi Merino <javi.merino@....com>

On Mon, Oct 26, 2015 at 11:15:30AM +0800, Chen Yu 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.
> 
> Here is the history of why current patch looks like this:
> https://patchwork.kernel.org/patch/7273041/
> 
> CC: <stable@...r.kernel.org> #3.18+
> Reference:https://bugzilla.kernel.org/show_bug.cgi?id=92431
> Tested-by: Manuel Krause <manuelkrause@...scape.net>
> Tested-by: szegad <szegadlo@...zta.onet.pl>
> Tested-by: prash <prash.n.rao@...il.com>
> Tested-by: amish <ammdispose-arch@...oo.com>
> Signed-off-by: Zhang Rui <rui.zhang@...el.com>
> Signed-off-by: Chen Yu <yu.c.chen@...el.com>
> ---
>  drivers/thermal/thermal_core.c | 14 +++++++++++++-
>  include/linux/thermal.h        |  1 +
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index abeb995..f36d0bd 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1341,6 +1341,7 @@ int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
>  	if (!result) {
>  		list_add_tail(&dev->tz_node, &tz->thermal_instances);
>  		list_add_tail(&dev->cdev_node, &cdev->thermal_instances);
> +		atomic_set(&tz->need_update, 1);
>  	}
>  	mutex_unlock(&cdev->lock);
>  	mutex_unlock(&tz->lock);
> @@ -1450,6 +1451,7 @@ __thermal_cooling_device_register(struct device_node *np,
>  				  const struct thermal_cooling_device_ops *ops)
>  {
>  	struct thermal_cooling_device *cdev;
> +	struct thermal_zone_device *pos = NULL;
>  	int result;
>  
>  	if (type && strlen(type) >= THERMAL_NAME_LENGTH)
> @@ -1494,6 +1496,12 @@ __thermal_cooling_device_register(struct device_node *np,
>  	/* Update binding information for 'this' new cdev */
>  	bind_cdev(cdev);
>  
> +	mutex_lock(&thermal_list_lock);
> +	list_for_each_entry(pos, &thermal_tz_list, node)
> +		if (atomic_cmpxchg(&pos->need_update, 1, 0))
> +			thermal_zone_device_update(pos);
> +	mutex_unlock(&thermal_list_lock);
> +
>  	return cdev;
>  }
>  
> @@ -1826,6 +1834,8 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
>  	tz->trips = trips;
>  	tz->passive_delay = passive_delay;
>  	tz->polling_delay = polling_delay;
> +	/* A new thermal zone needs to be updated anyway. */
> +	atomic_set(&tz->need_update, 1);
>  
>  	dev_set_name(&tz->device, "thermal_zone%d", tz->id);
>  	result = device_register(&tz->device);
> @@ -1921,7 +1931,9 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
>  	INIT_DELAYED_WORK(&(tz->poll_queue), thermal_zone_device_check);
>  
>  	thermal_zone_device_reset(tz);
> -	thermal_zone_device_update(tz);
> +	/* Update the new thermal zone and mark it as already updated. */
> +	if (atomic_cmpxchg(&tz->need_update, 1, 0))
> +		thermal_zone_device_update(tz);
>  
>  	return tz;
>  
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 5bcabc7..4298418 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -195,6 +195,7 @@ struct thermal_zone_device {
>  	int emul_temperature;
>  	int passive;
>  	unsigned int forced_passive;
> +	atomic_t need_update;

Please document this field in the kernel-doc comment for struct
thermal_zone_device.

Cheers,
Javi

>  	struct thermal_zone_device_ops *ops;
>  	struct thermal_zone_params *tzp;
>  	struct thermal_governor *governor;
> -- 
> 1.8.4.2
> 
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