Re: [patch] pm: fix runtime powermanagement's /sys interface

Pavel Machek
2006-01-05T23:08:49Z

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On Čt 05-01-06 23:27:05, Dominik Brodowski wrote:
> On Thu, Jan 05, 2006 at 11:23:38PM +0100, Pavel Machek wrote:
> > > In addition, your patch breaks pcmcia / pcmciautils which already uses
> > > numbers (which I already had to change from "3" to "2" before...).
> >
> > pcmcia actually uses this? Ouch. Do you just read the power file, or
> > do you write to it, too?
>
> Reading and writing. Replacement for "cardctl suspend" and "cardctl resume".
>
>
> static int pccardctl_power_one(unsigned long socket_no, unsigned int device,
> unsigned int power)
> {
> int ret;
> char file[SYSFS_PATH_MAX];
> struct sysfs_attribute *attr;
>
> snprintf(file, SYSFS_PATH_MAX,
> "/sys/bus/pcmcia/devices/%lu.%u/power/state",
> socket_no, device);
>
> attr = sysfs_open_attribute(file);
> if (!attr)
> return -ENODEV;
>
> ret = sysfs_write_attribute(attr, power ? "2" : "0", 1);
>
> sysfs_close_attribute(attr);
>
> return (ret);
> }
>
>
> NB: it will break one day, one way or another, when gregkh makes the
> /sys/class -> /sys/devices conversion. However, I'd want to try not to break
> the new pcmciautils userspace too often...

Ok, so lets at least add value-checking to .../power file, and prevent
userspace see changes to PM_EVENT_SUSPEND value. 2 and 0 are now
"arbitrary cookies". I'd like to use "on" and "off", but pcmcia
apparently depends on "2" and "0", so...

Any objections?

Signed-off-by: Pavel Machek <pavel@suse.cz>
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
@@ -27,22 +27,25 @@

static ssize_t state_show(struct device * dev, struct device_attribute *attr, char * buf)
{
- return sprintf(buf, "%u\n", dev->power.power_state.event);
+ if (dev->power.power_state.event)
+ return sprintf(buf, "2\n");
+ else
+ return sprintf(buf, "0\n");
}

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)
- error = dpm_runtime_suspend(dev, state);
- else
+ state.event = PM_EVENT_SUSPEND;
+ if ((n == 1) && !strncmp(buf, "2", 1)) {
dpm_runtime_resume(dev);
+ error = 0;
+ }
+ if ((n == 1) && !strncmp(buf, "0", 1))
+ error = dpm_runtime_suspend(dev, state);
+
return error ? error : n;
}

--
Thanks, Sharp!

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