[PATCH 4.4 032/113] usb: ehci: change order of register cleanup during shutdown

Greg Kroah-Hartman
2016-09-05T17:31:25Z

From: Marc Ohlf <ohlf@mkt-sys.de>

commit bc337b51508beb2d039aff5074a76cfe1c212030 upstream.

In ehci_turn_off_all_ports() all EHCI port registers are cleared to zero.
On some hardware, this can lead to an system hang,
when ehci_port_power() accesses the already cleared registers.

This patch changes the order of cleanup.
First call ehci_port_power() which respects the current bits in
port status registers
and afterwards cleanup the hard way by setting everything to zero.

Signed-off-by: Marc Ohlf <ohlf@mkt-sys.de>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/host/ehci-hcd.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -332,11 +332,11 @@ static void ehci_turn_off_all_ports(stru
int port = HCS_N_PORTS(ehci->hcs_params);

while (port--) {
- ehci_writel(ehci, PORT_RWC_BITS,
- &ehci->regs->port_status[port]);
spin_unlock_irq(&ehci->lock);
ehci_port_power(ehci, port, false);
spin_lock_irq(&ehci->lock);
+ ehci_writel(ehci, PORT_RWC_BITS,
+ &ehci->regs->port_status[port]);
}
}