| Message ID | 200908272120.56021.rjw@sisk.pl (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
Hi Rafael, On Thu, Aug 27, 2009 at 09:20:55PM +0200, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rjw@sisk.pl> > > Add sysfs attribute power/async for every device allowing the user > space to access the device's power.async_suspend flag and modify it, > if necessary. > I don't think we should let users meddle with individual devices; one global flag should be enough to work around "broken-at-the-moment" issues.
On Thursday 27 August 2009, Dmitry Torokhov wrote: > Hi Rafael, > > On Thu, Aug 27, 2009 at 09:20:55PM +0200, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki <rjw@sisk.pl> > > > > Add sysfs attribute power/async for every device allowing the user > > space to access the device's power.async_suspend flag and modify it, > > if necessary. > > > > I don't think we should let users meddle with individual devices; > one global flag should be enough to work around "broken-at-the-moment" > issues. Well, this patch is handy for testing if anyone is interested, so I posted it. It isn't exactly safe, though, you're right. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri 2009-08-28 00:24:06, Rafael J. Wysocki wrote: > On Thursday 27 August 2009, Dmitry Torokhov wrote: > > Hi Rafael, > > > > On Thu, Aug 27, 2009 at 09:20:55PM +0200, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki <rjw@sisk.pl> > > > > > > Add sysfs attribute power/async for every device allowing the user > > > space to access the device's power.async_suspend flag and modify it, > > > if necessary. > > > > > > > I don't think we should let users meddle with individual devices; > > one global flag should be enough to work around "broken-at-the-moment" > > issues. > > Well, this patch is handy for testing if anyone is interested, so I posted it. > > It isn't exactly safe, though, you're right. I guess it would be acceptable to let the users disable it per-driver... but if we can get without that, it would be better. (it is obviously ok for debugging). Pavel
Index: linux-2.6/drivers/base/power/sysfs.c =================================================================== --- linux-2.6.orig/drivers/base/power/sysfs.c +++ linux-2.6/drivers/base/power/sysfs.c @@ -38,6 +38,22 @@ * wakeup events internally (unless they are disabled), keeping * their hardware in low power modes whenever they're unused. This * saves runtime power, without requiring system-wide sleep states. + * + * async - Report/change current async suspend setting for the device + * + * If set, the PM core will attempt to suspend and resume the device during + * system power transitions (e.g. suspend to RAM, hibernation) in parallel + * with other devices it doesn't appear to depend on (to the PM core's + * knowledge). + * + * + "enabled\n" to permit the asynchronous suspend/resume of the device + * + "disabled\n" to forbid it + * + * NOTE: It generally is unsafe to permit the asynchronous suspend/resume + * of a device unless it is certain that all of the PM dependencies of the + * device are known to the PM core. However, for some devices this + * attribute is set to "enabled" by the kernel and in that cases it should + * be safe to leave the default value. */ static const char enabled[] = "enabled"; @@ -77,9 +93,40 @@ wake_store(struct device * dev, struct d static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store); +#ifdef CONFIG_PM_SLEEP +static ssize_t async_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + return sprintf(buf, "%s\n", + device_async_suspend_enabled(dev) ? enabled : disabled); +} + +static ssize_t async_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t n) +{ + char *cp; + int len = n; + + cp = memchr(buf, '\n', n); + if (cp) + len = cp - buf; + if (len == sizeof enabled - 1 && strncmp(buf, enabled, len) == 0) + device_enable_async_suspend(dev, true); + else if (len == sizeof disabled - 1 && strncmp(buf, disabled, len) == 0) + device_enable_async_suspend(dev, false); + else + return -EINVAL; + return n; +} + +static DEVICE_ATTR(async, 0644, async_show, async_store); +#endif /* CONFIG_PM_SLEEP */ static struct attribute * power_attrs[] = { &dev_attr_wakeup.attr, +#ifdef CONFIG_PM_SLEEP + &dev_attr_async.attr, +#endif NULL, }; static struct attribute_group pm_attr_group = { Index: linux-2.6/include/linux/device.h =================================================================== --- linux-2.6.orig/include/linux/device.h +++ linux-2.6/include/linux/device.h @@ -478,6 +478,11 @@ static inline void device_enable_async_s dev->power.async_suspend = enable; } +static inline bool device_async_suspend_enabled(struct device *dev) +{ + return !!dev->power.async_suspend; +} + void driver_init(void); /*