Re: Runtime device power management in userspace

[Pavel Machek <pavel@suse.cz>]

On Út 27-12-05 12:40:10, Patrick Mochel wrote:
> On Tue, 27 Dec 2005, Pavel Machek wrote:
> > On Út 27-12-05 11:29:56, Patrick Mochel wrote:
> > > But, in some cases, peple are going to care about the intermediate
> > > states, and we'll need to support them. It's simple enought to know
> > > what states a PCI device supports, so I don't understand where the
> > > complexity comes in.. ?
> >
> > Someone has to test all that... Unless we have in-tree driver that
> > wants use intermediate states, I think supporting them is bad idea.
> 
> I don't understand what your issue is; perhaps you could explain it a bit
> better. There is no additional work on the part of the core, nor any
> additional complication in supporting 4 possible power states vs
> supporting 2 vs supporting any arbitrary number that the driver and device
> implement.

Well, I can do two states today, with the patch below :-). Actually it
should work today as-is: writing 0/2 does mostly right think now.

> I did not suggest that we make the drivers support intermediate states; I
> only stated that there are some drivers and devices that can and will
> implement them, and that there are cases in which it will make sense to
> enter them from userpsace.

Ok.

> I admit I made a mistake in suggesting the interface - we wouldn't want to
> simply export all the PM states that are present in the device's config
> space. We would really only want to export the states that the driver says
> it supports. But, that could be any number of states, above and
> beyond (or

Ok.
								Pavel

diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -33,15 +33,12 @@ static ssize_t state_show(struct device 
 static ssize_t state_store(struct device * dev, struct device_attribute *attr, const char * buf, size_t n)
 {
 	pm_message_t state;
-	char * rest;
-	int error = 0;
+	int error = -EINVAL;
 
-	state.event = simple_strtoul(buf, &rest, 10);
-	if (*rest)
-		return -EINVAL;
-	if (state.event)
+	state.event = PM_EVENT_SUSPEND;
+	if ((n == 2) && !strncmp(buf, "on", min(n, 2)))
 		error = dpm_runtime_suspend(dev, state);
-	else
+	if ((n == 7) && !strncmp(buf, "suspend", min(n, 7)))
 		dpm_runtime_resume(dev);
 	return error ? error : n;
 }


-- 
Thanks, Sharp!