Re: [PATCH v2 3/4] thermal: of: Extend of-thermal to export table of trip points
From: Guenter Roeck
Date: Wed Nov 26 2014 - 16:13:07 EST
On 11/26/2014 12:43 PM, navneet kumar wrote:
Hi Eduardo, Lukasz,
[Combining my concerns as a single text blob here]
I. Firstly, with the current patch
1. is it really needed to duplicate the struct thermal_trip? Why don’t
we get rid of the __thermal_trip and stay with the 'thermal_trip' ? it
is not a big change.
2. gtrips is not updated on "set_trip_temp" etc. actions via sysfs. (am
I missing something?).
II. The other concern is more of a design question
1. Do we intend to keep the of-thermal as a middle layer between the
thermal_core and the sensor device? OR, is the role of of-thermal just
to parse the DT and opt out ? currently of-thermal is somewhat a hybrid
of these as, in addition to parsing the dt, it holds on to the data
related to trip points etc. etc.
2. assuming latter is true (OF is just a dt parser helper): we should
not be adding more intelligence and dependencies linked to the OF.
3. assuming former is true (OF is a well-defined middle layer): All is
good till the point OF maintains the trip points (which is a good thing
since, OF caches on to the data); BUT, if we expose this information to
the sensor device too (as this patch is doing),
3a. we violate the layering principle :-)
3b. more importantly, this is all just excessive logic that we
put in which *could be useful* only if we intend to extend the
role of OF as a trip point management layer that does more than
just holding on to the data. This may include -
-> The sensor devices to know nothing about the
trip_points, instead the sensor devices would work on
"temperature thresholds" and OF would map sensor
thresholds to the actual trip points as needed
(configured from DT); while the sensor devices stick to
using "thresholds".
-> Queuing from above, sensors, most of the time, only
need to know a high and a low temp threshold; which
essentially is a subset of the active/passive etc. trip
points. Calculation of that based on the current temp,
as of today is replicated across all the sensor drivers
and can be hoisted up to the of-thermal.
Sorry, lost you here. What replicated calculation do you refer to ?
Thanks,
Guenter
Seems like this is the opportune time to make a call about the role of of-thermal?
On 11/26/2014 07:18 AM, Eduardo Valentin wrote:
* PGP Signed by an unknown key
Hello,
On Wed, Nov 26, 2014 at 09:35:10AM +0100, Lukasz Majewski wrote:
Hi Eduardo,
Hello Lukasz,
On Thu, Nov 20, 2014 at 05:21:27PM +0100, Lukasz Majewski wrote:
This patch extends the of-thermal.c to export copy of trip points
for a given thermal zone.
Thermal drivers should use of_thermal_get_trip_points() method to
get pointer to table of thermal trip points.
Signed-off-by: Lukasz Majewski <l.majewski@xxxxxxxxxxx>
---
Changes for v2:
- New patch - as suggested by Eduardo Valentin
---
drivers/thermal/of-thermal.c | 33
+++++++++++++++++++++++++++++++++ drivers/thermal/thermal_core.h |
7 +++++++ include/linux/thermal.h | 14 ++++++++++++++
3 files changed, 54 insertions(+)
diff --git a/drivers/thermal/of-thermal.c
b/drivers/thermal/of-thermal.c index 336af7f..33921c5 100644
--- a/drivers/thermal/of-thermal.c
+++ b/drivers/thermal/of-thermal.c
@@ -89,6 +89,7 @@ struct __thermal_zone {
/* trip data */
int ntrips;
struct __thermal_trip *trips;
+ struct thermal_trip *gtrips;
Do we really need this duplication ?
/* cooling binding data */
int num_tbps;
@@ -152,6 +153,27 @@ bool of_thermal_is_trip_en(struct
thermal_zone_device *tz, int trip) return true;
}
+/**
+ * of_thermal_get_trip_points - function to get access to a
globally exported
+ * trip points
+ *
+ * @tz: pointer to a thermal zone
+ *
+ * This function provides a pointer to the copy of trip points
table
+ *
+ * Return: pointer to trip points table, NULL otherwise
+ */
+const struct thermal_trip * const
+of_thermal_get_trip_points(struct thermal_zone_device *tz)
+{
+ struct __thermal_zone *data = tz->devdata;
+
+ if (!data)
+ return NULL;
+
+ return data->gtrips;
+}
+
EXPORT_SYMBOL_GPL(of_thermal_get_trip_points);
Ok.
static int of_thermal_get_trend(struct thermal_zone_device *tz,
int trip, enum thermal_trend *trend)
{
@@ -767,6 +789,16 @@ thermal_of_build_thermal_zone(struct
device_node *np) goto free_tbps;
}
+ tz->gtrips = kcalloc(tz->ntrips, sizeof(*tz->gtrips),
GFP_KERNEL);
+ if (!tz->gtrips) {
+ ret = -ENOMEM;
+ goto free_tbps;
+ }
+
+ for (i = 0; i < tz->ntrips; i++)
+ memcpy(&(tz->gtrips[i]),
&(tz->trips[i].temperature),
+ sizeof(*tz->gtrips));
+
finish:
of_node_put(child);
tz->mode = THERMAL_DEVICE_DISABLED;
@@ -793,6 +825,7 @@ static inline void of_thermal_free_zone(struct
__thermal_zone *tz) {
int i;
+ kfree(tz->gtrips);
for (i = 0; i < tz->num_tbps; i++)
of_node_put(tz->tbps[i].cooling_device);
kfree(tz->tbps);
Couldn't find the code that updates *gtrips as a result of set_trip_temp via
sysfs.
diff --git a/drivers/thermal/thermal_core.h
b/drivers/thermal/thermal_core.h index 466208c..a9580ca 100644
--- a/drivers/thermal/thermal_core.h
+++ b/drivers/thermal/thermal_core.h
@@ -91,6 +91,8 @@ int of_parse_thermal_zones(void);
void of_thermal_destroy_zones(void);
int of_thermal_get_ntrips(struct thermal_zone_device *);
bool of_thermal_is_trip_en(struct thermal_zone_device *, int);
+const struct thermal_trip * const
+of_thermal_get_trip_points(struct thermal_zone_device *);
#else
static inline int of_parse_thermal_zones(void) { return 0; }
static inline void of_thermal_destroy_zones(void) { }
@@ -102,6 +104,11 @@ static inline bool
of_thermal_is_trip_en(struct thermal_zone_device *, int) {
This produces compilation error when CONFIG_THERMAL_OF is not set.
Name the parameters to fix.
As all the other cases, I will fix that.
return 0;
}
+static inline const struct thermal_trip * const
+of_thermal_get_trip_points(struct thermal_zone_device *)
+{
+ return NULL;
+}
#endif
#endif /* __THERMAL_CORE_H__ */
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 5bc28a7..88d7249 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -303,6 +303,20 @@ struct thermal_zone_of_device_ops {
int (*get_trend)(void *, long *);
};
+/**
+ * struct thermal_trip - Structure representing themal trip points
exported from
+ * of-thermal
+ *
The only problem I have with this name is that would look like it is
in use in all thermal framework, which is not really the case. But I
do think having a type here is a good thing. So, not sure :-)
It can stay to be struct thermal_trip or we can rename it to
struct of_thermal_trip.
I'm fine with both names.
Leave it as 'thermal_trip'.
+ * @temperature: trip point temperature
+ * @hysteresis: trip point hysteresis
+ * @type: trip point type
+ */
+struct thermal_trip {
+ unsigned long int temperature;
+ unsigned long int hysteresis;
+ enum thermal_trip_type type;
+};
+
/* Function declarations */
#ifdef CONFIG_THERMAL_OF
struct thermal_zone_device *
--
2.0.0.rc2
--
Best regards,
Lukasz Majewski
Samsung R&D Institute Poland (SRPOL) | Linux Platform Group
* Unknown Key
* 0x7DA4E256
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