xhci: prevent U2 link power state if Intel tier policy prevented U1

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>
Link: https://lore.kernel.org/r/20220511220450.85367-8-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index e66a031..d957eac 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4888,9 +4888,6 @@ 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)
@@ -4899,7 +4896,7 @@ 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");
@@ -4940,9 +4937,6 @@ 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.
         */
@@ -5049,6 +5043,9 @@ 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) {