xhci: A default implementation for Ux timeout calculation and tier policy check

As best case, a host controller should support U0 to U1 switching for
the devices connected below any tier of hub level supported by usb
specification. Therefore xhci_check_tier_policy should always return
success as default implementation.

A host should be able to issue LGO_Ux after the timeout calculated as
per definition of system exit latency defined in C.1.5.2. Therefore
xhci_calculate_ux_timeout returns ux_params.sel as the default
implementation.

Use default calculation in absence of any vendor specific limitations.

Signed-off-by: Pratyush Anand <pratyush.anand@st.com>
Tested-by: Aymen Bouattay <aymen.bouattay@st.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci.c

@@ -4288,8 +4288,7 @@ static u16 xhci_get_timeout_no_hub_lpm(struct usb_device *udev,
 	return USB3_LPM_DISABLED;
 }
 
-/* Returns the hub-encoded U1 timeout value.
- * The U1 timeout should be the maximum of the following values:
+/* The U1 timeout should be the maximum of the following values:
  *  - For control endpoints, U1 system exit latency (SEL) * 3
  *  - For bulk endpoints, U1 SEL * 5
  *  - For interrupt endpoints:
@@ -4297,7 +4296,8 @@ static u16 xhci_get_timeout_no_hub_lpm(struct usb_device *udev,
  *    - Periodic EPs, max(105% of bInterval, U1 SEL * 2)
  *  - For isochronous endpoints, max(105% of bInterval, U1 SEL * 2)
  */
-static u16 xhci_calculate_intel_u1_timeout(struct usb_device *udev,
+static unsigned long long xhci_calculate_intel_u1_timeout(
+		struct usb_device *udev,
 		struct usb_endpoint_descriptor *desc)
 {
 	unsigned long long timeout_ns;
@@ -4329,11 +4329,28 @@ static u16 xhci_calculate_intel_u1_timeout(struct usb_device *udev,
 		return 0;
 	}
 
-	/* The U1 timeout is encoded in 1us intervals. */
-	timeout_ns = DIV_ROUND_UP_ULL(timeout_ns, 1000);
-	/* Don't return a timeout of zero, because that's USB3_LPM_DISABLED. */
+	return timeout_ns;
+}
+
+/* Returns the hub-encoded U1 timeout value. */
+static u16 xhci_calculate_u1_timeout(struct xhci_hcd *xhci,
+		struct usb_device *udev,
+		struct usb_endpoint_descriptor *desc)
+{
+	unsigned long long timeout_ns;
+
+	if (xhci->quirks & XHCI_INTEL_HOST)
+		timeout_ns = xhci_calculate_intel_u1_timeout(udev, desc);
+	else
+		timeout_ns = udev->u1_params.sel;
+
+	/* The U1 timeout is encoded in 1us intervals.
+	 * Don't return a timeout of zero, because that's USB3_LPM_DISABLED.
+	 */
 	if (timeout_ns == USB3_LPM_DISABLED)
-		timeout_ns++;
+		timeout_ns = 1;
+	else
+		timeout_ns = DIV_ROUND_UP_ULL(timeout_ns, 1000);
 
 	/* If the necessary timeout value is bigger than what we can set in the
 	 * USB 3.0 hub, we have to disable hub-initiated U1.
@@ -4345,14 +4362,14 @@ static u16 xhci_calculate_intel_u1_timeout(struct usb_device *udev,
 	return xhci_get_timeout_no_hub_lpm(udev, USB3_LPM_U1);
 }
 
-/* Returns the hub-encoded U2 timeout value.
- * The U2 timeout should be the maximum of:
+/* The U2 timeout should be the maximum of:
  *  - 10 ms (to avoid the bandwidth impact on the scheduler)
  *  - largest bInterval of any active periodic endpoint (to avoid going
  *    into lower power link states between intervals).
  *  - the U2 Exit Latency of the device
  */
-static u16 xhci_calculate_intel_u2_timeout(struct usb_device *udev,
+static unsigned long long xhci_calculate_intel_u2_timeout(
+		struct usb_device *udev,
 		struct usb_endpoint_descriptor *desc)
 {
 	unsigned long long timeout_ns;
@@ -4368,6 +4385,21 @@ static u16 xhci_calculate_intel_u2_timeout(struct usb_device *udev,
 	if (u2_del_ns > timeout_ns)
 		timeout_ns = u2_del_ns;
 
+	return timeout_ns;
+}
+
+/* Returns the hub-encoded U2 timeout value. */
+static u16 xhci_calculate_u2_timeout(struct xhci_hcd *xhci,
+		struct usb_device *udev,
+		struct usb_endpoint_descriptor *desc)
+{
+	unsigned long long timeout_ns;
+
+	if (xhci->quirks & XHCI_INTEL_HOST)
+		timeout_ns = xhci_calculate_intel_u2_timeout(udev, desc);
+	else
+		timeout_ns = udev->u2_params.sel;
+
 	/* The U2 timeout is encoded in 256us intervals */
 	timeout_ns = DIV_ROUND_UP_ULL(timeout_ns, 256 * 1000);
 	/* If the necessary timeout value is bigger than what we can set in the
@@ -4386,13 +4418,10 @@ static u16 xhci_call_host_update_timeout_for_endpoint(struct xhci_hcd *xhci,
 		enum usb3_link_state state,
 		u16 *timeout)
 {
-	if (state == USB3_LPM_U1) {
-		if (xhci->quirks & XHCI_INTEL_HOST)
-			return xhci_calculate_intel_u1_timeout(udev, desc);
-	} else {
-		if (xhci->quirks & XHCI_INTEL_HOST)
-			return xhci_calculate_intel_u2_timeout(udev, desc);
-	}
+	if (state == USB3_LPM_U1)
+		return xhci_calculate_u1_timeout(xhci, udev, desc);
+	else if (state == USB3_LPM_U2)
+		return xhci_calculate_u2_timeout(xhci, udev, desc);
 
 	return USB3_LPM_DISABLED;
 }
@@ -4469,7 +4498,8 @@ static int xhci_check_tier_policy(struct xhci_hcd *xhci,
 {
 	if (xhci->quirks & XHCI_INTEL_HOST)
 		return xhci_check_intel_tier_policy(udev, state);
-	return -EINVAL;
+	else
+		return 0;
 }
 
 /* Returns the U1 or U2 timeout that should be enabled.