Re: How to perform runtime pm for usb hcds?
Alan Stern <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
On Wed, 21 Nov 2007, jidong xiao wrote: > > localhost:~ # echo 3 >/sys/devices/pci0000:00/0000:00:1d.0/power/state > > -bash: echo: write error: Invalid argument > > > > But this command failed to work.(both usbcore and uhci-hcd are inserted already) > > The kernel I am using is 2.6.22.1. > > > > Regards > > Jason > > > > I also tried echo -n 3 > ... > > echo -n 3 >/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-0:1.0/power/state > echo -n 3 >/sys/devices/pci0000:00/0000:00:1d.0/usb1/power/state > echo -n 3 >/sys/devices/pci0000:00/0000:00:1d.0/power/state > > The first two commands works well,but the third one doesn't. Yes. The PM core was changed (I don't remember exactly when) so that writes to power/state wouldn't always be accepted for all devices. You can undo that change by commenting out the "if" and "return" statements at the start of drivers/base/power/sysfs.c:state_store(). But it's easier just to use the PCI-suspend patch I posted before. > Then I do: > > localhost:~ # lspci -vvv -s 1d.0 > 00:1d.0 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 > Family) USB UHCI #1 (rev 03) (prog-if 00 [UHCI]) > Subsystem: Dell Unknown device 018f > Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- > ParErr- Stepping- SERR- FastB2B- > Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium > >TAbort- <TAbort- <MAbort- >SERR- <PERR- > Latency: 0 > Interrupt: pin A routed to IRQ 16 > Region 4: I/O ports at bf80 [size=32] > > Is "Cap-" indicating that the controller is not able to perform power > management? That's right. Most UHCI controllers can't do it, although some of the controllers made by VIA can. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel