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
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