[PATCH] [30/50] EHCI: only power off port if over-current is active

Andi Kleen
2011-07-28T23:44:46Z

From: Sergei Shtylyov <sshtylyov@ru.mvista.com>

[ upstream commit 81463c1d707186adbbe534016cd1249edeab0dac ]

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@ru.mvista.com>
Cc: stable@kernel.org
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

Index: linux-2.6.35.y/drivers/usb/host/ehci-hub.c
===================================================================
--- linux-2.6.35.y.orig/drivers/usb/host/ehci-hub.c
+++ linux-2.6.35.y/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)) {
ehci_writel(ehci,
temp & ~(PORT_RWC_BITS | PORT_POWER),
status_reg);
+ temp = ehci_readl(ehci, status_reg);
}
}