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    Subject[34-longterm 137/179] EHCI: only power off port if over-current is active
    From: Sergei Shtylyov <>

    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.

    commit 81463c1d707186adbbe534016cd1249edeab0dac upstream.

    MAX4967 USB power supply chip we use on our boards signals over-current when
    power is not enabled; once it's enabled, over-current signal returns to normal.
    That unfortunately caused the endless stream of "over-current change on port"
    messages. The EHCI root hub code reacts on every over-current signal change
    with powering off the port -- such change event is generated the moment the
    port power is enabled, so once enabled the power is immediately cut off.
    I think we should only cut off power when we're seeing the active over-current
    signal, so I'm adding such check to that code. I also think that the fact that
    we've cut off the port power should be reflected in the result of GetPortStatus
    request immediately, hence I'm adding a PORTSCn register readback after write...

    Signed-off-by: Sergei Shtylyov <>
    Acked-by: Alan Stern <>
    Signed-off-by: Greg Kroah-Hartman <>
    Signed-off-by: Paul Gortmaker <>
    drivers/usb/host/ehci-hub.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
    index 1b2af4d..ae32f02 100644
    --- a/drivers/usb/host/ehci-hub.c
    +++ b/drivers/usb/host/ehci-hub.c
    @@ -837,10 +837,11 @@ static int ehci_hub_control (
    * power switching; they're allowed to just limit the
    * current. khubd will turn the power back on.
    - if (HCS_PPC (ehci->hcs_params)){
    + if ((temp & PORT_OC) && HCS_PPC(ehci->hcs_params)) {
    temp & ~(PORT_RWC_BITS | PORT_POWER),
    + temp = ehci_readl(ehci, status_reg);


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