On Mon, Sep 17, 2018 at 11:24:20AM +0300, Mathias Nyman wrote: > On 14.09.2018 16:00, Greg KH wrote: > > On Fri, Sep 14, 2018 at 03:33:30PM +0300, Mathias Nyman wrote: > > > From: Anshuman Gupta <anshuman.gupta@xxxxxxxxx> > > > > > > When USB bus host controller root hub resumes from autosuspend, > > > it immediately tries to enter auto-suspend, but there can be a > > > scenario when root hub is resuming its usb2 ports, in that particular > > > case USB host controller auto suspend fails since it is busy > > > to resuming its usb2 ports. > > > > > > This makes multiple failed cycles of auto-suspend until all usb2 > > > ports of host controller root hub do not resume. > > > > > > This patch uses USB core framework usb_hcd_start_port_resume, > > > usb_hcd_end_port_resume API's in order to autoresume/autosuspend > > > root hub properly. > > > > > > Signed-off-by: Anshuman Gupta <anshuman.gupta@xxxxxxxxx> > > > Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> > > > > Not needed in stable? Does this fix a specific commit? > > > > thanks, > > > > greg k-h > > > > This improves a bad initial design that prevented autosuspend by > returning -EBUSY in xhci_bus_suspend() if a usb2 port was resuming. > > Instead increment usage count on the roothub to prevent pm from polling > xhci_bus_suspend(). This is also what EHCI does. > > I'm not sure If this fixes a actual bug for Anshuman Gupta caused by > the -EBUSY polling,(4.19 +stable), or if this is just a improvement in > suspend/resume code for xhci (4.20). > > Anshuman Gupta, any comments? This patch is not fixing any bug. This patch provide improvement in runtime suspend/resume path of xhci. > > -Mathias -- Thanks, Anshuman
