On Tue, 5 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 causes 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 only 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 shut off the port power should be reflected in the result of
> GetPortStatus() immediately, hence I'm also changing the place where the
> PORT_POWER bit is cleared...
>
> 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 | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> 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 +891,10 @@ 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)){
> - ehci_writel(ehci,
> - temp & ~(PORT_RWC_BITS | PORT_POWER),
> - status_reg);
> + if ((temp & PORT_OC) && HCS_PPC(ehci->hcs_params)) {
> + temp &= ~PORT_POWER;
> + ehci_writel(ehci, temp & ~PORT_RWC_BITS,
> + status_reg);
> }
> }
Instead of removing the PORT_POWER bit from temp, how about re-reading
temp from the register after turning off the power? That way the final
port status value will be consistent.
Otherwise this seems okay.
Alan Stern
--
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
