From 3cd12f91514da6893954de479dc60b16d3b381f4 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 29 May 2014 12:58:46 -0700 Subject: [PATCH] usb: force warm reset to break link re-connect livelock Resuming a powered down port sometimes results in the port state being stuck in the training sequence. hub 3-0:1.0: debounce: port 1: total 2000ms stable 0ms status 0x2e0 port1: can't get reconnection after setting port power on, status -110 hub 3-0:1.0: port 1 status 0000.02e0 after resume, -19 usb 3-1: can't resume, status -19 hub 3-0:1.0: logical disconnect on port 1 In the case above we wait for the port re-connect timeout of 2 seconds and observe that the port status is USB_SS_PORT_LS_POLLING (although it is likely toggling between this state and USB_SS_PORT_LS_RX_DETECT). This is indicative of a case where the device is failing to progress the link training state machine. It is resolved by issuing a warm reset to get the hub and device link state machines back in sync. hub 3-0:1.0: debounce: port 1: total 2000ms stable 0ms status 0x2e0 usb usb3: port1 usb_port_runtime_resume requires warm reset hub 3-0:1.0: port 1 not warm reset yet, waiting 50ms usb 3-1: reset SuperSpeed USB device number 2 using xhci_hcd After a reconnect timeout when we expect the device to be present, force a warm reset of the device. Note that we can not simply look at the link status to determine if a warm reset is required as any of the training states USB_SS_PORT_LS_POLLING, USB_SS_PORT_LS_RX_DETECT, or USB_SS_PORT_LS_COMP_MOD are valid states that do not indicate the need for warm reset by themselves. Cc: Alan Stern Cc: Kukjin Kim Cc: Vincent Palatin Cc: Lan Tianyu Cc: Ksenia Ragiadakou Cc: Vivek Gautam Cc: Douglas Anderson Cc: Felipe Balbi Cc: Sunil Joshi Cc: Hans de Goede Acked-by: Julius Werner Signed-off-by: Dan Williams Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/hub.c | 36 +++++++++++++++++++++++++----------- drivers/usb/core/hub.h | 2 ++ drivers/usb/core/port.c | 21 ++++++++++++--------- 3 files changed, 39 insertions(+), 20 deletions(-) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index b90c6287bf47..88f1db27e0af 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2587,13 +2587,20 @@ static int hub_port_reset(struct usb_hub *hub, int port1, /* Is a USB 3.0 port in the Inactive or Compliance Mode state? * Port worm reset is required to recover */ -static bool hub_port_warm_reset_required(struct usb_hub *hub, u16 portstatus) +static bool hub_port_warm_reset_required(struct usb_hub *hub, int port1, + u16 portstatus) { - return hub_is_superspeed(hub->hdev) && - (((portstatus & USB_PORT_STAT_LINK_STATE) == - USB_SS_PORT_LS_SS_INACTIVE) || - ((portstatus & USB_PORT_STAT_LINK_STATE) == - USB_SS_PORT_LS_COMP_MOD)) ; + u16 link_state; + + if (!hub_is_superspeed(hub->hdev)) + return false; + + if (test_bit(port1, hub->warm_reset_bits)) + return true; + + link_state = portstatus & USB_PORT_STAT_LINK_STATE; + return link_state == USB_SS_PORT_LS_SS_INACTIVE + || link_state == USB_SS_PORT_LS_COMP_MOD; } static int hub_port_wait_reset(struct usb_hub *hub, int port1, @@ -2630,7 +2637,7 @@ static int hub_port_wait_reset(struct usb_hub *hub, int port1, if ((portstatus & USB_PORT_STAT_RESET)) return -EBUSY; - if (hub_port_warm_reset_required(hub, portstatus)) + if (hub_port_warm_reset_required(hub, port1, portstatus)) return -ENOTCONN; /* Device went away? */ @@ -2730,9 +2737,10 @@ static int hub_port_reset(struct usb_hub *hub, int port1, if (status < 0) goto done; - if (hub_port_warm_reset_required(hub, portstatus)) + if (hub_port_warm_reset_required(hub, port1, portstatus)) warm = true; } + clear_bit(port1, hub->warm_reset_bits); /* Reset the port */ for (i = 0; i < PORT_RESET_TRIES; i++) { @@ -2769,7 +2777,8 @@ static int hub_port_reset(struct usb_hub *hub, int port1, &portstatus, &portchange) < 0) goto done; - if (!hub_port_warm_reset_required(hub, portstatus)) + if (!hub_port_warm_reset_required(hub, port1, + portstatus)) goto done; /* @@ -2856,8 +2865,13 @@ static int check_port_resume_type(struct usb_device *udev, { struct usb_port *port_dev = hub->ports[port1 - 1]; + /* Is a warm reset needed to recover the connection? */ + if (status == 0 && udev->reset_resume + && hub_port_warm_reset_required(hub, port1, portstatus)) { + /* pass */; + } /* Is the device still present? */ - if (status || port_is_suspended(hub, portstatus) || + else if (status || port_is_suspended(hub, portstatus) || !port_is_power_on(hub, portstatus) || !(portstatus & USB_PORT_STAT_CONNECTION)) { if (status >= 0) @@ -4872,7 +4886,7 @@ static void port_event(struct usb_hub *hub, int port1) * Warm reset a USB3 protocol port if it's in * SS.Inactive state. */ - if (hub_port_warm_reset_required(hub, portstatus)) { + if (hub_port_warm_reset_required(hub, port1, portstatus)) { dev_dbg(&port_dev->dev, "do warm reset\n"); if (!udev || !(portstatus & USB_PORT_STAT_CONNECTION) || udev->state == USB_STATE_NOTATTACHED) { diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h index 326308e53961..c77d8778af4b 100644 --- a/drivers/usb/core/hub.h +++ b/drivers/usb/core/hub.h @@ -52,6 +52,8 @@ struct usb_hub { unsigned long power_bits[1]; /* ports that are powered */ unsigned long child_usage_bits[1]; /* ports powered on for children */ + unsigned long warm_reset_bits[1]; /* ports requesting warm + reset recovery */ #if USB_MAXCHILDREN > 31 /* 8*sizeof(unsigned long) - 1 */ #error event_bits[] is too short! #endif diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c index fe1b6d0967e3..cd3f9dc24a06 100644 --- a/drivers/usb/core/port.c +++ b/drivers/usb/core/port.c @@ -103,16 +103,19 @@ static int usb_port_runtime_resume(struct device *dev) msleep(hub_power_on_good_delay(hub)); if (udev && !retval) { /* - * Attempt to wait for usb hub port to be reconnected in order - * to make the resume procedure successful. The device may have - * disconnected while the port was powered off, so ignore the - * return status. + * Our preference is to simply wait for the port to reconnect, + * as that is the lowest latency method to restart the port. + * However, there are cases where toggling port power results in + * the host port and the device port getting out of sync causing + * a link training live lock. Upon timeout, flag the port as + * needing warm reset recovery (to be performed later by + * usb_port_resume() as requested via usb_wakeup_notification()) */ - retval = hub_port_debounce_be_connected(hub, port1); - if (retval < 0) - dev_dbg(&port_dev->dev, "can't get reconnection after setting port power on, status %d\n", - retval); - retval = 0; + if (hub_port_debounce_be_connected(hub, port1) < 0) { + dev_dbg(&port_dev->dev, "reconnect timeout\n"); + if (hub_is_superspeed(hdev)) + set_bit(port1, hub->warm_reset_bits); + } /* Force the child awake to revalidate after the power loss. */ if (!test_and_set_bit(port1, hub->child_usage_bits)) { -- 2.20.1