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Date: Wed, 16 Jan 2013 15:33:21 +0800
From: Zhang Rui <rui.zhang@...el.com>
To: Amit Daniel Kachhap <amit.daniel@...sung.com>
Cc: linux-pm@...r.kernel.org, jonghwa3.lee@...sung.com,
linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] thermal: sysfs: Add a new sysfs node emul_temp
Hi, Amit,
On Sun, 2013-01-06 at 16:08 -0800, Amit Daniel Kachhap wrote:
> This patch adds support to set the emulated temperature method in
> thermal zone (sensor). After setting this feature thermal zone must
> report this temperature and not the actual temperature. The actual
> implementation of this emulated temperature is based on sensor
> capability or platform specific. This is useful in debugging different
> temperature threshold and its associated cooling action. Writing 0 on
> this node should disable emulation.
Question:
will this bring hardware issue? Say, critical temperature reached while
in emulation mode?
As this is for debug purpose, I'd prefer to have a seperate Kconfig
option for this feature.
> Signed-off-by: Amit Daniel Kachhap <amit.daniel@...sung.com>
> ---
> Documentation/thermal/sysfs-api.txt | 14 ++++++++++++++
> drivers/thermal/thermal_sys.c | 26 ++++++++++++++++++++++++++
> include/linux/thermal.h | 1 +
> 3 files changed, 41 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
> index 88c0233..e8f2ee4 100644
> --- a/Documentation/thermal/sysfs-api.txt
> +++ b/Documentation/thermal/sysfs-api.txt
> @@ -55,6 +55,8 @@ temperature) and throttle appropriate devices.
> .get_trip_type: get the type of certain trip point.
> .get_trip_temp: get the temperature above which the certain trip point
> will be fired.
> + .set_emul_temp: set the emulation temperature which helps in debugging
> + different threshold temperature points.
>
> 1.1.2 void thermal_zone_device_unregister(struct thermal_zone_device *tz)
>
> @@ -153,6 +155,7 @@ Thermal zone device sys I/F, created once it's registered:
> |---trip_point_[0-*]_temp: Trip point temperature
> |---trip_point_[0-*]_type: Trip point type
> |---trip_point_[0-*]_hyst: Hysteresis value for this trip point
> + |---emul_temp: Emulated temperature set node
>
> Thermal cooling device sys I/F, created once it's registered:
> /sys/class/thermal/cooling_device[0-*]:
> @@ -252,6 +255,17 @@ passive
> Valid values: 0 (disabled) or greater than 1000
> RW, Optional
>
> +emul_temp
> + Interface to set the emulated temperature method in thermal zone
> + (sensor). After setting this feature thermal zone must report
> + this temperature and not the actual temperature. The actual
> + implementation of this emulated temperature is platform specific.
can we have a pure software temperature emulation method?
say, the generic thermal layer caches the emulated temperature value,
and hook it in update_temperature()?
This is also useful for testing in polling mode, and it does not require
platform specific callback support. I mean thermal_ops->set_emul_temp is
optional, but thermal emulation is always available for all platforms.
thanks,
rui
> + This is useful in debugging different temperature threshold and its
> + associated cooling action. Writing 0 on this node should disable
> + emulation.
> + Unit: millidegree Celsius
> + WO, Optional
> +
> *****************************
> * Cooling device attributes *
> *****************************
> diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
> index 8c8ce80..ecdfc7d 100644
> --- a/drivers/thermal/thermal_sys.c
> +++ b/drivers/thermal/thermal_sys.c
> @@ -700,11 +700,31 @@ policy_show(struct device *dev, struct device_attribute *devattr, char *buf)
> return sprintf(buf, "%s\n", tz->governor->name);
> }
>
> +static ssize_t
> +emul_temp_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct thermal_zone_device *tz = to_thermal_zone(dev);
> + int ret;
> + unsigned long temperature;
> +
> + if (!tz->ops->set_emul_temp)
> + return -EPERM;
> +
> + if (kstrtoul(buf, 10, &temperature))
> + return -EINVAL;
> +
> + ret = tz->ops->set_emul_temp(tz, temperature);
> +
> + return ret ? ret : count;
> +}
> +
> static DEVICE_ATTR(type, 0444, type_show, NULL);
> static DEVICE_ATTR(temp, 0444, temp_show, NULL);
> static DEVICE_ATTR(mode, 0644, mode_show, mode_store);
> static DEVICE_ATTR(passive, S_IRUGO | S_IWUSR, passive_show, passive_store);
> static DEVICE_ATTR(policy, S_IRUGO | S_IWUSR, policy_show, policy_store);
> +static DEVICE_ATTR(emul_temp, S_IWUSR, NULL, emul_temp_store);
>
> /* sys I/F for cooling device */
> #define to_cooling_device(_dev) \
> @@ -1592,6 +1612,12 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
> goto unregister;
> }
>
> + if (ops->set_emul_temp) {
> + result = device_create_file(&tz->device, &dev_attr_emul_temp);
> + if (result)
> + goto unregister;
> + }
> +
> /* Create policy attribute */
> result = device_create_file(&tz->device, &dev_attr_policy);
> if (result)
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 883bcda..fbb87d4 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -123,6 +123,7 @@ struct thermal_zone_device_ops {
> int (*set_trip_hyst) (struct thermal_zone_device *, int,
> unsigned long);
> int (*get_crit_temp) (struct thermal_zone_device *, unsigned long *);
> + int (*set_emul_temp) (struct thermal_zone_device *, unsigned long);
> int (*get_trend) (struct thermal_zone_device *, int,
> enum thermal_trend *);
> int (*notify) (struct thermal_zone_device *, int,
--
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