ehci_hub_control does the following related to overcurrent handling (simplified): temp = ehci_readl(ehci, status_reg); if (temp & PORT_OCC) { status |= USB_PORT_STAT_C_OVERCURRENT << 16; if (temp & PORT_OC) { ehci_port_power(ehci, wIndex, false); temp = ehci_readl(ehci, status_reg); } } if (temp & PORT_OC) status |= USB_PORT_STAT_OVERCURRENT; At least on my i.MX25 based machine rereading the PORTSC register after port power was removed doesn't yield PORT_OC any more. The result is that repeatedly changes related to over-current (status |= USB_PORT_STAT_C_OVERCURRENT << 16) are reported, but USB_PORT_STAT_OVERCURRENT doesn't toggle as expected and is always unset. As a side effect the message dev_err(&port_dev->dev, "over-current condition\n"); from drivers/usb/core/hub.c's port_event() never makes it to the user. Rereading the value was introduced with the rationale: 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... As there are no further expected changes, just mask the PORT_POWER bit instead of rereading the register. An alternative would be to check for PORT_OC before checking for PORT_OCC. Fixes: 81463c1d7071 ("EHCI: only power off port if over-current is active") Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> --- drivers/usb/host/ehci-hub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c index df169c8e7225..08f59654654b 100644 --- a/drivers/usb/host/ehci-hub.c +++ b/drivers/usb/host/ehci-hub.c @@ -1031,7 +1031,7 @@ int ehci_hub_control( spin_unlock_irqrestore(&ehci->lock, flags); ehci_port_power(ehci, wIndex, false); spin_lock_irqsave(&ehci->lock, flags); - temp = ehci_readl(ehci, status_reg); + temp |= ~PORT_POWER; } } -- 2.14.2 -- 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