On Mon, Aug 01, 2016 at 06:07:17PM +0200, Alan Stern wrote: > On Mon, 1 Aug 2016, Marc Ohlf wrote: > > > In ehci_turn_off_all_ports() all EHCI port register bits > > (except the PORT_RWC_BITS) are set to zero. > > Even the PORT_WRC_BITS are set to 0. Oddly enough, the way to set > those bits to 0 is to write a 1 to them (see Table 2-16 in the EHCI > spec). Thanks for correction, i will improve that in an v2. > > > On some hardware, this can lead to an system hang, > > when ehci_port_power() accesses the already cleaned registers. > > > > This patch changes the order of cleanup. > > First call ehci_port_power() which respects the current bits in > > port status registers > > and afterwards cleanup the hard way by setting everything else to zero. > > > > Signed-off-by: Marc Ohlf <ohlf@xxxxxxxxxx> > > --- > > drivers/usb/host/ehci-hcd.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c > > index a962b89..1e5f529 100644 > > --- a/drivers/usb/host/ehci-hcd.c > > +++ b/drivers/usb/host/ehci-hcd.c > > @@ -332,11 +332,11 @@ static void ehci_turn_off_all_ports(struct ehci_hcd *ehci) > > int port = HCS_N_PORTS(ehci->hcs_params); > > > > while (port--) { > > - ehci_writel(ehci, PORT_RWC_BITS, > > - &ehci->regs->port_status[port]); > > spin_unlock_irq(&ehci->lock); > > ehci_port_power(ehci, port, false); > > spin_lock_irq(&ehci->lock); > > + ehci_writel(ehci, PORT_RWC_BITS, > > + &ehci->regs->port_status[port]); > > } > > } > I'm new to the mailing lists, so I've some questions. > Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> I should include your Ack in my v2 patch signoff area, right? > > This should be marked for the -stable kernels as well. Marking this for -stable kernels means cc it to stable mailing list, right? > > Alan Stern > > > Marc Ohlf -- 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