linux-kernel - [ 032/167] [PATCH] EHCI: always clear the STS

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Message-Id: <20120509055034.039563429@decadent.org.uk>
Date:	Wed, 09 May 2012 06:51:01 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Alan Stern <stern@...land.harvard.edu>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [ 032/167] [PATCH] EHCI: always clear the STS_FLR status bit

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alan Stern <stern@...land.harvard.edu>

commit 2fbe2bf1fd37f9d99950bd8d8093623cf22cf08b upstream.

This patch (as1544) fixes a problem affecting some EHCI controllers.
They can generate interrupts whenever the STS_FLR status bit is turned
on, even though that bit is masked out in the Interrupt Enable
register.

Since the driver doesn't use STS_FLR anyway, the patch changes the
interrupt routine to clear that bit whenever it is set, rather than
leaving it alone.

Signed-off-by: Alan Stern <stern@...land.harvard.edu>
Reported-and-tested-by: Tomoya MORINAGA <tomoya.rohm@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/host/ehci-hcd.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 95ca07a..4a3bc5b 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -858,8 +858,13 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 		goto dead;
 	}
 
+	/*
+	 * We don't use STS_FLR, but some controllers don't like it to
+	 * remain on, so mask it out along with the other status bits.
+	 */
+	masked_status = status & (INTR_MASK | STS_FLR);
+
 	/* Shared IRQ? */
-	masked_status = status & INTR_MASK;
 	if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED)) {
 		spin_unlock(&ehci->lock);
 		return IRQ_NONE;
-- 
1.7.10



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