On Tue, 25 Nov 2014, tianjulin wrote: > Hi Stern, > > *1*:I turn off media-change polling when connect sdcard-reader,the usb > bus still can't enter runtime suspend.I guss sdcard-reader can't enter > runtime suspend cause the usb bus cat't enter runtime suspend,but I > can't understand that why the sdcard-reader can't enter runtime suspend > if have no Operating. Because you have to enable runtime suspend. It is turned off by default. > *2*: connect USB storage,the run command as A->B->C->D,the usb bus still > can't enter runtime suspend. > *A：* > shell@byt_t_crv2:/sys/bus/usb/devices # ls > 1-0:1.0 > 1-2 > *1-2:1.0* > 2-0:1.0 > usb1 > usb2 > shell@byt_t_crv2:/sys/bus/usb/devices # > *B：* > shell@byt_t_crv2:/sys/bus/usb/devices/1-2:1.0/power # ls > shell@byt_t_crv2:/sys/bus/usb/devices/1-2:1.0/power # > have any files show. > > *C：* > shell@byt_t_crv2:/sys/bus/usb/devices/1-2/power # ls > active_duration > autosuspend > autosuspend_delay_ms > connected_duration > control > level > persist > runtime_active_time > runtime_status > runtime_suspended_time > shell@byt_t_crv2:/sys/bus/usb/devices/1-2/power # > > *D：* > shell@byt_t_crv2:#echo auto > /sys/bus/usb/devices/1-2/power/control > > > *3:*The bus won't enter runtime suspend until all of the devices attached > to the bus are in runtime suspend > ---------------why I have no any operation,connect usb and run "echo auto > control",the usb bus still can't runtime suspend? why usb storage can't enter runtime suspend if have no any operation? What you did isn't enough. You also need to enable runtime suspend for the card reader's sd device. For example, echo 1000 >/sys/bus/usb/devices/1-2:1.0/host2/target2:0:0/2:0:0:0/power/autosuspend_delay_ms echo auto >/sys/bus/usb/devices/1-2:1.0/host2/target2:0:0/2:0:0:0/power/control Some of those path names may be different on your system. Basically, you need to visit every "power" directory under /sys/bus/usb/devices/1-2, and make sure they contain "auto" in power/control and a reasonable value in power/autosuspend_delay_ms. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
