Patch "usb: ehci: change order of register cleanup during shutdown" has been added to the 4.4-stable tree

Patch "usb: ehci: change order of register cleanup during shutdown" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    usb: ehci: change order of register cleanup during shutdown

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-ehci-change-order-of-register-cleanup-during-shutdown.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From bc337b51508beb2d039aff5074a76cfe1c212030 Mon Sep 17 00:00:00 2001
From: Marc Ohlf <ohlf@mkt-sys.de>
Date: Wed, 3 Aug 2016 11:51:54 +0200
Subject: usb: ehci: change order of register cleanup during shutdown

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]);
 	}
 }
 


Patches currently in stable-queue which might be from ohlf@mkt-sys.de are

queue-4.4/usb-ehci-change-order-of-register-cleanup-during-shutdown.patch