On Wed, 6 Jul 2011, Sergei Shtylyov wrote:
> 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 <sshtylyov@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxx
>
> ---
> The patch is against the 'usb-linus' branch of Greg KH's usb-2.6.git...
>
> drivers/usb/host/ehci-hub.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> Index: usb-2.6/drivers/usb/host/ehci-hub.c
> ===================================================================
> --- usb-2.6.orig/drivers/usb/host/ehci-hub.c
> +++ usb-2.6/drivers/usb/host/ehci-hub.c
> @@ -891,10 +891,11 @@ 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)) {
> ehci_writel(ehci,
> temp & ~(PORT_RWC_BITS | PORT_POWER),
> status_reg);
> + temp = ehci_readl(ehci, status_reg);
> }
> }
>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
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