On Thu, Jul 19, 2018 at 12:23:22AM +0800, Kai-Heng Feng wrote: > From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> > > commit 229bc19fd7aca4f37964af06e3583c1c8f36b5d6 upstream. > > Don't rely on event interrupt (EINT) bit alone to detect pending port > change in resume. If no change event is detected the host may be suspended > again, oterwise roothubs are resumed. > > There is a lag in xHC setting EINT. If we don't notice the pending change > in resume, and the controller is runtime suspeded again, it causes the > event handler to assume host is dead as it will fail to read xHC registers > once PCI puts the controller to D3 state. > > [ 268.520969] xhci_hcd: xhci_resume: starting port polling. > [ 268.520985] xhci_hcd: xhci_hub_status_data: stopping port polling. > [ 268.521030] xhci_hcd: xhci_suspend: stopping port polling. > [ 268.521040] xhci_hcd: // Setting command ring address to 0x349bd001 > [ 268.521139] xhci_hcd: Port Status Change Event for port 3 > [ 268.521149] xhci_hcd: resume root hub > [ 268.521163] xhci_hcd: port resume event for port 3 > [ 268.521168] xhci_hcd: xHC is not running. > [ 268.521174] xhci_hcd: handle_port_status: starting port polling. > [ 268.596322] xhci_hcd: xhci_hc_died: xHCI host controller not responding, assume dead > > The EINT lag is described in a additional note in xhci specs 4.19.2: > > "Due to internal xHC scheduling and system delays, there will be a lag > between a change bit being set and the Port Status Change Event that it > generated being written to the Event Ring. If SW reads the PORTSC and > sees a change bit set, there is no guarantee that the corresponding Port > Status Change Event has already been written into the Event Ring." > > Cc: <stable@xxxxxxxxxxxxxxx> > Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> > --- > drivers/usb/host/xhci.c | 40 +++++++++++++++++++++++++++++++++++++--- > drivers/usb/host/xhci.h | 4 ++++ > 2 files changed, 41 insertions(+), 3 deletions(-) Any specific reason you sent this old patch that is already in Linus's tree out again to everyone? confused, greg k-h
