diff options
Diffstat (limited to 'drivers/usb/core/hub.c')
| -rw-r--r-- | drivers/usb/core/hub.c | 120 |
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. |