Thread (19 messages) 19 messages, 5 authors, 2014-10-26

Re: [RFC v3 PATCH 1/5] of: Add standard property for poweroff capability

From: Romain Perier <hidden>
Date: 2014-10-25 18:36:44
Also in: linux-pm, lkml

Hi Johan,

If that's still possible to do these changes, I am opened to suggestions.

2014-10-23 11:53 GMT+02:00 Johan Hovold [off-list ref]:
[ +CC: Guenter, Lee, linux-pm ]

On Tue, Oct 14, 2014 at 06:31:09AM +0000, Romain Perier wrote:
quoted
Several drivers create their own devicetree property when they register
poweroff capabilities. This is for example the case for mfd, regulator
or power drivers which define "vendor,system-power-controller" property.
This patch adds support for a standard property "poweroff-source"
Shouldn't this property really be called "power-off-source" or even
"power-off-controller"?

The power-off handler call-chain infrastructure is about to be merged
and will be using power[-_ ]off (i.e. not "poweroff") consistently (at
least in its interface).
"poweroff" or "power-off", I don't care. If people prefer "power-off",
choose this name :)
Furthermore, isn't "controller" as in "power-off-controller" more
appropriate than "source" in this case? We have wake-up sources, which
might appear analogous, but that really isn't the same thing.
As I said, the idea with "power-off-source" (or "poweroff-source",
that's not the point here) is to mark the device as able to poweroff
the system, like "wakeup-source" which marks the device as able to
wakeup the system.
This is why I chose this name, because it is quite similar to wakeup
property except that it is for handling power, so it did make sense to
me.

The question is: what is the advantage of the suffix "controller"
compared to "source" ?
I now this has already been merged to the regulator tree, but there's
still still time to fix this.
quoted
which marks the device as able to shutdown the system.

Signed-off-by: Romain Perier <redacted>
---
 include/linux/of.h | 11 +++++++++++
 1 file changed, 11 insertions(+)
diff --git a/include/linux/of.h b/include/linux/of.h
index 6545e7a..27b3ba1 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -866,4 +866,15 @@ static inline int of_changeset_update_property(struct of_changeset *ocs,
 /* CONFIG_OF_RESOLVE api */
 extern int of_resolve_phandles(struct device_node *tree);

+/**
+ * of_system_has_poweroff_source - Tells if poweroff-source is found for device_node
+ * @np: Pointer to the given device_node
+ *
+ * return true if present false otherwise
+ */
+static inline bool of_system_has_poweroff_source(const struct device_node *np)
Why "system_has"? Shouldn't this be of_is_power_off_source (controller)?
Note that the current custom vendor properties contain "system-" as prefix ;)

we have several possibilities:
- of_system_has_power_off_source()
- of_has_power_off_source()

We should either to use "has" or "is" as prefix because that's a
predicate function.
I would prefer "has" since it refers to a property inside a node :
this node "has" the corresponding property, so "is" is not a good
candidate.

Have a nice day,
Romain
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