linux-kernel - [PATCH v3] usb/host/ehci-hub: Fix the issue EG20T USB host controller has long resuming time, when pen drive is attached.

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Date:	Fri, 13 Jul 2012 11:43:42 +0900
From:	Tomoya MORINAGA <tomoya.rohm@...il.com>
To:	Alan Stern <stern@...land.harvard.edu>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Tomoya MORINAGA <tomoya.rohm@...il.com>
Subject: [PATCH v3] usb/host/ehci-hub: Fix the issue EG20T USB host controller has long resuming time, when pen drive is attached.

Intel EG20T USB host controller does not send SOF in resuming time after
suspending, if the FLR bit was not cleared. When pen drive is attached,
the controller has a long resuming time to try re-connect it.
This patch clear the FLR bit in suspending time for fixing the issue.

Signed-off-by: Tomoya MORINAGA <tomoya.rohm@...il.com>
---
v3: Update comments from Alan Stern
	Add comment in the source code.

v2: Update comments from Alan Stern
        Add patch description
        Always clear the STS_FLR flag.
---
 drivers/usb/host/ehci-hub.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index fc9e7cc..278b589 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -318,6 +318,13 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
 	ehci_readl(ehci, &ehci->regs->intr_enable);
 
 	ehci->next_statechange = jiffies + msecs_to_jiffies(10);
+
+	/* Intel EG20T USB host controller does not send SOF
+	 * in resuming time after suspending, if the FLR bit was not cleared.
+	 * Therefore clear the FLR bit in here.
+	 */
+	ehci_writel(ehci, STS_FLR, &ehci->regs->status);
+
 	spin_unlock_irq (&ehci->lock);
 
 	/* ehci_work() may have re-enabled the watchdog timer, which we do not
-- 
1.7.4.4

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