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path: root/drivers/usb/core/hub.c
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Diffstat (limited to 'drivers/usb/core/hub.c')
-rw-r--r--drivers/usb/core/hub.c120
1 files changed, 84 insertions, 36 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index d1efc7141333..86658a81d284 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -48,6 +48,7 @@
#define USB_TP_TRANSMISSION_DELAY 40 /* ns */
#define USB_TP_TRANSMISSION_DELAY_MAX 65535 /* ns */
+#define USB_PING_RESPONSE_TIME 400 /* ns */
/* Protect struct usb_device->state and ->children members
* Note: Both are also protected by ->dev.sem, except that ->state can
@@ -182,8 +183,9 @@ int usb_device_supports_lpm(struct usb_device *udev)
}
/*
- * Set the Maximum Exit Latency (MEL) for the host to initiate a transition from
- * either U1 or U2.
+ * Set the Maximum Exit Latency (MEL) for the host to wakup up the path from
+ * U1/U2, send a PING to the device and receive a PING_RESPONSE.
+ * See USB 3.1 section C.1.5.2
*/
static void usb_set_lpm_mel(struct usb_device *udev,
struct usb3_lpm_parameters *udev_lpm_params,
@@ -193,35 +195,37 @@ static void usb_set_lpm_mel(struct usb_device *udev,
unsigned int hub_exit_latency)
{
unsigned int total_mel;
- unsigned int device_mel;
- unsigned int hub_mel;
/*
- * Calculate the time it takes to transition all links from the roothub
- * to the parent hub into U0. The parent hub must then decode the
- * packet (hub header decode latency) to figure out which port it was
- * bound for.
- *
- * The Hub Header decode latency is expressed in 0.1us intervals (0x1
- * means 0.1us). Multiply that by 100 to get nanoseconds.
+ * tMEL1. time to transition path from host to device into U0.
+ * MEL for parent already contains the delay up to parent, so only add
+ * the exit latency for the last link (pick the slower exit latency),
+ * and the hub header decode latency. See USB 3.1 section C 2.2.1
+ * Store MEL in nanoseconds
*/
total_mel = hub_lpm_params->mel +
- (hub->descriptor->u.ss.bHubHdrDecLat * 100);
+ max(udev_exit_latency, hub_exit_latency) * 1000 +
+ hub->descriptor->u.ss.bHubHdrDecLat * 100;
/*
- * How long will it take to transition the downstream hub's port into
- * U0? The greater of either the hub exit latency or the device exit
- * latency.
- *
- * The BOS U1/U2 exit latencies are expressed in 1us intervals.
- * Multiply that by 1000 to get nanoseconds.
+ * tMEL2. Time to submit PING packet. Sum of tTPTransmissionDelay for
+ * each link + wHubDelay for each hub. Add only for last link.
+ * tMEL4, the time for PING_RESPONSE to traverse upstream is similar.
+ * Multiply by 2 to include it as well.
*/
- device_mel = udev_exit_latency * 1000;
- hub_mel = hub_exit_latency * 1000;
- if (device_mel > hub_mel)
- total_mel += device_mel;
- else
- total_mel += hub_mel;
+ total_mel += (__le16_to_cpu(hub->descriptor->u.ss.wHubDelay) +
+ USB_TP_TRANSMISSION_DELAY) * 2;
+
+ /*
+ * tMEL3, tPingResponse. Time taken by device to generate PING_RESPONSE
+ * after receiving PING. Also add 2100ns as stated in USB 3.1 C 1.5.2.4
+ * to cover the delay if the PING_RESPONSE is queued behind a Max Packet
+ * Size DP.
+ * Note these delays should be added only once for the entire path, so
+ * add them to the MEL of the device connected to the roothub.
+ */
+ if (!hub->hdev->parent)
+ total_mel += USB_PING_RESPONSE_TIME + 2100;
udev_lpm_params->mel = total_mel;
}
@@ -4113,6 +4117,47 @@ static int usb_set_lpm_timeout(struct usb_device *udev,
}
/*
+ * Don't allow device intiated U1/U2 if the system exit latency + one bus
+ * interval is greater than the minimum service interval of any active
+ * periodic endpoint. See USB 3.2 section 9.4.9
+ */
+static bool usb_device_may_initiate_lpm(struct usb_device *udev,
+ enum usb3_link_state state)
+{
+ unsigned int sel; /* us */
+ int i, j;
+
+ if (state == USB3_LPM_U1)
+ sel = DIV_ROUND_UP(udev->u1_params.sel, 1000);
+ else if (state == USB3_LPM_U2)
+ sel = DIV_ROUND_UP(udev->u2_params.sel, 1000);
+ else
+ return false;
+
+ for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
+ struct usb_interface *intf;
+ struct usb_endpoint_descriptor *desc;
+ unsigned int interval;
+
+ intf = udev->actconfig->interface[i];
+ if (!intf)
+ continue;
+
+ for (j = 0; j < intf->cur_altsetting->desc.bNumEndpoints; j++) {
+ desc = &intf->cur_altsetting->endpoint[j].desc;
+
+ if (usb_endpoint_xfer_int(desc) ||
+ usb_endpoint_xfer_isoc(desc)) {
+ interval = (1 << (desc->bInterval - 1)) * 125;
+ if (sel + 125 > interval)
+ return false;
+ }
+ }
+ }
+ return true;
+}
+
+/*
* Enable the hub-initiated U1/U2 idle timeouts, and enable device-initiated
* U1/U2 entry.
*
@@ -4184,20 +4229,23 @@ static void usb_enable_link_state(struct usb_hcd *hcd, struct usb_device *udev,
* U1/U2_ENABLE
*/
if (udev->actconfig &&
- usb_set_device_initiated_lpm(udev, state, true) == 0) {
- if (state == USB3_LPM_U1)
- udev->usb3_lpm_u1_enabled = 1;
- else if (state == USB3_LPM_U2)
- udev->usb3_lpm_u2_enabled = 1;
- } else {
- /* Don't request U1/U2 entry if the device
- * cannot transition to U1/U2.
- */
- usb_set_lpm_timeout(udev, state, 0);
- hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state);
+ usb_device_may_initiate_lpm(udev, state)) {
+ if (usb_set_device_initiated_lpm(udev, state, true)) {
+ /*
+ * Request to enable device initiated U1/U2 failed,
+ * better to turn off lpm in this case.
+ */
+ usb_set_lpm_timeout(udev, state, 0);
+ hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state);
+ return;
+ }
}
-}
+ if (state == USB3_LPM_U1)
+ udev->usb3_lpm_u1_enabled = 1;
+ else if (state == USB3_LPM_U2)
+ udev->usb3_lpm_u2_enabled = 1;
+}
/*
* Disable the hub-initiated U1/U2 idle timeouts, and disable device-initiated
* U1/U2 entry.