Re: [PATCH 3/11] USB: interface PM state
Alan Stern <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
On Fri, 6 Apr 2007, David Brownell wrote: > I think the key thing to abstract from your comments below is that > this state was once used, but that's (thankfully) changed. > > In fact, the generalization is that since dev.power.power_state is > going to be removed (this summer!), we want to know sooner -- rather > than later! -- if we even care about it. Agreed. > > (There is an apparently unnecessary reference in > > usbtest.c, but it shouldn't be affected by this patch. It also has a > > race...) > > Presumably autoresume handles that issue now. It will, if anyone gets around to adding support for it to usbtest. Not a big job. > > BTW, the same is true for udev->dev.power.power_state, with two > > exceptions: > > > > At one point in hub.c the value is checked in lieu of looking > > at udev->state when CONFIG_USB_SUSPEND isn't set; > > > > At one place in hcd-pci.c the value for a root hub is checked -- > > this really should be replaced with a check for USB_STATE_SUSPENDED. > > Again, power_state clearly being on the way out, we have alternate > solutions for what it previously seemed to solve. Yes. However there is still one aspect for which we haven't fashioned a replacement -- the host controller devices themselves. Both the HCDs and usbcore are concerned with their power states in various places, and right now they all rely on checking dev.power.power_state. Perhaps we should add a field to struct usb_hcd for this purpose. Assuming we do, do you think that field would need to indicate anything other than "powered on" vs. "powered off"? That is, would the non-PCI drivers want to store different, more structured values? Or would they go somewhere else, in the driver's private data? Alan Stern ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel