On Thu, 1 May 2014, Dan Williams wrote:
> I've been testing this and the pm_request_resume() ends up leaving the
> usb device enabled indefinitely. It needs to be paired with a
> pm_runtime_autosuspend(), but at that point why not just add a
> usb_autoresume_device_async() helper.
Why didn't pm_request_resume() result in an autosuspend? I just tested
this patch on my system:
Index: usb-3.15/drivers/usb/core/sysfs.c
===================================================================
--- usb-3.15.orig/drivers/usb/core/sysfs.c
+++ usb-3.15/drivers/usb/core/sysfs.c
@@ -11,6 +11,7 @@
#include <linux/kernel.h>
+#include <linux/pm_runtime.h>
#include <linux/string.h>
#include <linux/usb.h>
#include <linux/usb/quirks.h>
@@ -55,6 +56,8 @@ static ssize_t bMaxPower_show(struct dev
if (actconfig)
rc = sprintf(buf, "%dmA\n", usb_get_max_power(udev, actconfig));
usb_unlock_device(udev);
+ dev_info(dev, "calling request_resume\n");
+ pm_request_resume(dev);
return rc;
}
static DEVICE_ATTR_RO(bMaxPower);
With no USB devices plugged into bus 1 and the root hub suspended,
doing "cat /sys/bus/usb/devices/usb1/bMaxPower" caused the root hub to
resume and suspend again shortly thereafter.
Alan Stern
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