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Date: Sun, 27 Jan 2013 19:32:02 -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>,
Kukjin Kim <kgene.kim@...sung.com>
Subject: Re: [PATCH 1/2] thermal: sysfs: Add a new sysfs node emul_temp
On Mon, Jan 21, 2013 at 7:20 PM, Zhang Rui <rui.zhang@...el.com> wrote:
> On Wed, 2013-01-16 at 11:30 -0800, amit kachhap wrote:
>> 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
>>
> No.
> We should not support emulation is CONFIG_THERMAL_EMULATION is cleared.
> And further more, for pure software emulation, we should check if the
> real temperature reaches critical trip point.
Yes agreed. Submitted the V2 version with your suggestion.
Thanks,
Amit Daniel
>
> thanks,
> rui
>> 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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