On Thu, Aug 16, 2012 at 12:38:33PM -0600, Stephen Warren wrote:

On 08/16/2012 12:08 AM, Alexandre Courbot wrote:

quoted

diff --git a/Documentation/power/power_seq.txt b/Documentation/power/power_seq.txt

quoted

+Usage by Drivers and Resources Management
+-----------------------------------------
+Power sequences make use of resources that must be properly allocated and
+managed. The power_seq_build() function builds a power sequence from the
+platform data. It also takes care of resolving and allocating the resources
+referenced by the sequence if needed:
+
+  struct power_seq *power_seq_build(struct device *dev, struct list_head *ress,
+                                    struct platform_power_seq *pseq);
+
+The 'dev' argument is the device in the name of which the resources are to be
+allocated.
+
+The 'ress' argument is a list to which the resolved resources are appended. This
+avoids allocating a resource referenced in several power sequences multiple
+times.

I see in other parts of the thread, there has been discussion re:
needing the separate ress parameter, and requiring the driver to pass
this in to multiple power_seq_build calls.

The way the pinctrl subsystem solved this was to have a single function
that parsed all pinctrl setting (c.f. all power sequences) at once, and
return a single handle. Later, the driver passes this handle
pinctrl_lookup_state(), along with the requested state (c.f. sequence
name) to search for, and finally passes that handle to
pinctrl_select_state(). Doing something similar here would result in:

struct power_seqs *power_seq_get(struct device *dev);
void power_seq_put(struct power_seqs *seqs);
struct power_seq *power_seq_lookup(struct power_seqs *seqs,
				const char *name);
int power_seq_executestruct power_seq *seq);

struct power_seqs *devm_power_seq_get(struct device *dev);
void devm_power_seq_put(struct power_seqs *seqs);

Hehe, this looks very much like what I had in mind when I proposed this
during the last version of this series. The nice thing about this is
that the API is very much in line with how other subsystems work.

Thierry