[PATCH 7/9] xhci: prevent U2 link power state if Intel tier policy prevented U1

[Mathias Nyman <mathias.nyman@linux.intel.com>]

Don't enable U1 or U2 Link powermanagenet (LPM) states for USB3
devices connected to tier 2 or further hubs.

For unknown reasons we previously only prevented U1.
Be consistent, and prevent both U1/U2 states if tier policy doesn't
allow LPM.

Also check the tier policy a bit earlier, and return if U1/U2 is
not allowed. This avoids unnecessary xhci MEL commands.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 19363f542d19..18306e28e7f8 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4886,9 +4886,6 @@ static int xhci_check_intel_tier_policy(struct usb_device *udev,
 	struct usb_device *parent;
 	unsigned int num_hubs;
 
-	if (state == USB3_LPM_U2)
-		return 0;
-
 	/* Don't enable U1 if the device is on a 2nd tier hub or lower. */
 	for (parent = udev->parent, num_hubs = 0; parent->parent;
 			parent = parent->parent)
@@ -4897,7 +4894,7 @@ static int xhci_check_intel_tier_policy(struct usb_device *udev,
 	if (num_hubs < 2)
 		return 0;
 
-	dev_dbg(&udev->dev, "Disabling U1 link state for device"
+	dev_dbg(&udev->dev, "Disabling U1/U2 link state for device"
 			" below second-tier hub.\n");
 	dev_dbg(&udev->dev, "Plug device into first-tier hub "
 			"to decrease power consumption.\n");
@@ -4938,9 +4935,6 @@ static u16 xhci_calculate_lpm_timeout(struct usb_hcd *hcd,
 		return timeout;
 	}
 
-	if (xhci_check_tier_policy(xhci, udev, state) < 0)
-		return timeout;
-
 	/* Gather some information about the currently installed configuration
 	 * and alternate interface settings.
 	 */
@@ -5047,6 +5041,9 @@ static int xhci_enable_usb3_lpm_timeout(struct usb_hcd *hcd,
 			!xhci->devs[udev->slot_id])
 		return USB3_LPM_DISABLED;
 
+	if (xhci_check_tier_policy(xhci, udev, state) < 0)
+		return USB3_LPM_DISABLED;
+
 	hub_encoded_timeout = xhci_calculate_lpm_timeout(hcd, udev, state);
 	mel = calculate_max_exit_latency(udev, state, hub_encoded_timeout);
 	if (mel < 0) {
-- 
2.25.1