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_default_tier_policy always returns
success.
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_default_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@xxxxxx>
---
drivers/usb/host/xhci.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 6cc58fe..930c01f 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4140,6 +4140,53 @@ static u16 xhci_get_timeout_no_hub_lpm(struct usb_device *udev,
return USB3_LPM_DISABLED;
}
+/* Returns the default hub-encoded U1 timeout value.
+ */
+static u16 xhci_calculate_default_u1_timeout(struct usb_device *udev,
+ struct usb_endpoint_descriptor *desc)
+{
+ unsigned long long timeout_ns;
+
+ timeout_ns = udev->u1_params.sel;
+
+ /* 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. */
+ if (timeout_ns == USB3_LPM_DISABLED)
+ timeout_ns++;
+
+ /* 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.
+ */
+ if (timeout_ns <= USB3_LPM_U1_MAX_TIMEOUT)
+ return timeout_ns;
+ dev_dbg(&udev->dev, "Hub-initiated U1 disabled "
+ "due to long timeout %llu ms\n", timeout_ns);
+ return xhci_get_timeout_no_hub_lpm(udev, USB3_LPM_U1);
+}
+
+/* Returns the default hub-encoded U2 timeout value.
+ */
+static u16 xhci_calculate_default_u2_timeout(struct usb_device *udev,
+ struct usb_endpoint_descriptor *desc)
+{
+ unsigned long long timeout_ns;
+
+ 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
+ * USB 3.0 hub, we have to disable hub-initiated U2.
+ */
+ if (timeout_ns <= USB3_LPM_U2_MAX_TIMEOUT)
+ return timeout_ns;
+ dev_dbg(&udev->dev, "Hub-initiated U2 disabled "
+ "due to long timeout %llu ms\n", timeout_ns);
+ return xhci_get_timeout_no_hub_lpm(udev, USB3_LPM_U2);
+}
+
+
/* Returns the hub-encoded U1 timeout value.
* The U1 timeout should be the maximum of the following values:
* - For control endpoints, U1 system exit latency (SEL) * 3
@@ -4241,9 +4288,13 @@ static u16 xhci_call_host_update_timeout_for_endpoint(struct xhci_hcd *xhci,
if (state == USB3_LPM_U1) {
if (xhci->quirks & XHCI_INTEL_HOST)
return xhci_calculate_intel_u1_timeout(udev, desc);
+ else
+ return xhci_calculate_default_u1_timeout(udev, desc);
} else {
if (xhci->quirks & XHCI_INTEL_HOST)
return xhci_calculate_intel_u2_timeout(udev, desc);
+ else
+ return xhci_calculate_default_u2_timeout(udev, desc);
}
return USB3_LPM_DISABLED;
@@ -4291,6 +4342,14 @@ static int xhci_update_timeout_for_interface(struct xhci_hcd *xhci,
return 0;
}
+static int xhci_check_default_tier_policy(struct usb_device *udev,
+ enum usb3_link_state state)
+{
+ /* Keeep Ux enabled for all devices */
+
+ return 0;
+}
+
static int xhci_check_intel_tier_policy(struct usb_device *udev,
enum usb3_link_state state)
{
@@ -4321,6 +4380,8 @@ static int xhci_check_tier_policy(struct xhci_hcd *xhci,
{
if (xhci->quirks & XHCI_INTEL_HOST)
return xhci_check_intel_tier_policy(udev, state);
+ else
+ return xhci_check_default_tier_policy(udev, state);
return -EINVAL;
}
--
1.8.1.2
--
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