[PATCH] xhci: tegra: Delay for disabling LFPS detector

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Occasionally, we are seeing some SuperSpeed devices resumes right after
being directed to U3. This commits add 500us delay to ensure LFPS
detector is disabled before sending ACK to firmware.

[   16.099363] tegra-xusb 70090000.usb: entering ELPG
[   16.104343] tegra-xusb 70090000.usb: 2-1 isn't suspended: 0x0c001203
[   16.114576] tegra-xusb 70090000.usb: not all ports suspended: -16
[   16.120789] tegra-xusb 70090000.usb: entering ELPG failed

Signed-off-by: JC Kuo <jckuo@xxxxxxxxxx>
---
 drivers/usb/host/xhci-tegra.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
index 934be1686352..20cdc11f7dc6 100644
--- a/drivers/usb/host/xhci-tegra.c
+++ b/drivers/usb/host/xhci-tegra.c
@@ -623,6 +623,12 @@ static void tegra_xusb_mbox_handle(struct tegra_xusb *tegra,
 								     enable);
 			if (err < 0)
 				break;
+
+			/*
+			 * wait 500us for LFPS detector to be disabled before sending ACK
+			 */
+			if (!enable)
+				usleep_range(500, 1000);
 		}
 
 		if (err < 0) {
-- 
2.25.1





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