linux-kernel - [PATCH 1/1] driver,usb: Fix a warning in uhci-hcd driver

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Date:	Thu, 25 Apr 2013 15:11:09 +0800
From:	"Li, Zhen-Hua" <zhen-hual@...com>
To:	<stern@...land.harvard.edu>, <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Cc:	<tom.vaden@...com>, "Li, Zhen-Hua" <zhen-hual@...com>
Subject: [PATCH 1/1] driver,usb: Fix a warning in uhci-hcd driver

This patch is trying to fix this bug on SLES11 SP2:
    https://bugzilla.novell.com/show_bug.cgi?id=817035

On a large HP system with 64T memory and 60 logical cpus, when usb
driver inits the iLo Virtual USB Controller, there comes a warning
"Controller not stopped yet!". It is because driver does not wait
enough time. So driver should wait and retry if found controller 
 not stopped.

Signed-off-by: Li, Zhen-Hua <zhen-hual@...com>
Signed-off-by: Tom Vaden <tom.vaden@...com>
---
 drivers/usb/host/uhci-hcd.c |   17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
index 4a86b63..d592e22 100644
--- a/drivers/usb/host/uhci-hcd.c
+++ b/drivers/usb/host/uhci-hcd.c
@@ -277,6 +277,9 @@ static int global_suspend_mode_is_broken(struct uhci_hcd *uhci)
 		uhci->global_suspend_mode_is_broken(uhci) : 0;
 }
 
+#define UHCI_SUSPENDRH_RETRY_MAX      10
+#define UHCI_SUSPENDRH_RETRY_DELAY    100
+
 static void suspend_rh(struct uhci_hcd *uhci, enum uhci_rh_state new_state)
 __releases(uhci->lock)
 __acquires(uhci->lock)
@@ -284,6 +287,8 @@ __acquires(uhci->lock)
 	int auto_stop;
 	int int_enable, egsm_enable, wakeup_enable;
 	struct usb_device *rhdev = uhci_to_hcd(uhci)->self.root_hub;
+	int try;
+	u16 stopped;
 
 	auto_stop = (new_state == UHCI_RH_AUTO_STOPPED);
 	dev_dbg(&rhdev->dev, "%s%s\n", __func__,
@@ -355,7 +360,17 @@ __acquires(uhci->lock)
 		if (uhci->dead)
 			return;
 	}
-	if (!(uhci_readw(uhci, USBSTS) & USBSTS_HCH))
+
+	for (try = 0; try < UHCI_SUSPENDRH_RETRY_MAX; try++) {
+		/* For some devices, for example, HP iLo usb controller,
+		 * we need to wait for more time and retry. 
+		 */
+		stopped = uhci_readw(uhci, USBSTS) & USBSTS_HCH;
+		if (stopped)
+			break;
+		udelay(UHCI_SUSPENDRH_RETRY_DELAY);
+	}
+	if (!stopped)
 		dev_warn(uhci_dev(uhci), "Controller not stopped yet!\n");
 
 	uhci_get_current_frame_number(uhci);
-- 
1.7.10.4

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