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Date: Wed, 16 Jan 2013 11:30:35 -0800
From: amit kachhap <amit.kachhap@...il.com>
To: Zhang Rui <rui.zhang@...el.com>
Cc: linux-pm@...r.kernel.org, jonghwa3.lee@...sung.com,
linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
Durgadoss <durgadoss.r@...el.com>
Subject: Re: [PATCH 1/2] thermal: sysfs: Add a new sysfs node emul_temp
Hi Rui,
Thanks for the review comments,
On Tue, Jan 15, 2013 at 11:33 PM, Zhang Rui <rui.zhang@...el.com> wrote:
> 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?
No emulation does cause any h/w issue.
>
> As this is for debug purpose, I'd prefer to have a seperate Kconfig
> option for this feature.
Yes agreed. Will re-submit with kconfig option.
>
>> 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.
Yes It makes sense and we can have pure software emulation and use the
cached temperature when no platform call is registered. In my case I
needed this in h/w so to have the same sensor trigger interrupts
behaviour.
So the code flow can be like this,
#ifdef CONFIG_THERMAL_EMULATION
if (thermal_ops->set_emul_temp)
then pass emul_temp to platform and use the normal platform
thermal_ops->get_temp
else
Store it locally and use emul_temp instead of calling platform
thermal_ops->get_temp
#endif
I will re-submit with this change.
Thanks,
Amit
>
> 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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