On Thu, 8 May 2014, Hans de Goede wrote: > Hi, > > On 05/08/2014 12:00 AM, Maxime Ripard wrote: > > On Wed, May 07, 2014 at 10:25:55AM -0400, Alan Stern wrote: > >> On Tue, 6 May 2014, Maxime Ripard wrote: > >> > >>> From: Boris BREZILLON <boris.brezillon@xxxxxxxxxxxxxxxxxx> > >>> > >>> On the Allwinner's A31 SoC the reset line connected to the EHCI IP has to > >>> be deasserted for the EHCI block to be usable. > >>> > >>> Add support for an optional reset controller that will be deasserted on > >>> power off and asserted on power on. > >>> > >>> Signed-off-by: Boris BREZILLON <boris.brezillon@xxxxxxxxxxxxxxxxxx> > >>> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> > >> > >> Is this really a _reset_ line? That is, when you assert the reset > >> line, does it actually reset the EHCI controller, or does it merely > >> leave the controller in a partially powered-down state? > > > > It actually resets the whole controller. > > > >> The difference is important. During suspend, the controller is > >> supposed to remember the state of the port connections as well as other > >> settings. If it doesn't, the controller and all attached USB devices > >> will have to be reinitialized every time the controller resumes, which > >> will increase the latency. > > > > So you're saying that we should move this to the probe then? > > Yes. That's right. The controller should not be reset during suspend, if you can possibly avoid it. There isn't any real benefit to asserting the reset signal during suspend, is there? I mean, it won't use any less power, right? 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
