[PATCH v2 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3

[PATCH v2 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3

[Kai-Heng Feng]

The xHCI spec doesn't specify the upper bound of U3 transition time. For
some devices 20ms is not enough, so we need to make sure the link state
is in U3 before further actions.

I've tried to use U3 Entry Capability by setting U3 Entry Enable in
config register, however the port change event for U3 transition
interrupts the system suspend process.

For now let's use the less ideal method by polling PLS.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v2:
 - Remove some redundant debug messages.
 - Use msleep loop outside if spinlock to stop pegging CPU.

 drivers/usb/host/xhci-hub.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 7a3a29e5e9d2..d3c5bcf76755 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1313,7 +1313,16 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 			xhci_set_link_state(xhci, ports[wIndex], link_state);
 
 			spin_unlock_irqrestore(&xhci->lock, flags);
-			msleep(20); /* wait device to enter */
+			if (link_state == USB_SS_PORT_LS_U3) {
+				int retries = 10;
+
+				while (retries--) {
+					msleep(10); /* wait device to enter */
+					temp = readl(ports[wIndex]->addr);
+					if ((temp & PORT_PLS_MASK) == XDEV_U3)
+						break;
+				}
+			}
 			spin_lock_irqsave(&xhci->lock, flags);
 
 			temp = readl(ports[wIndex]->addr);
-- 
2.17.1

[PATCH v2 2/3] xhci: Wait until link state trainsits to U0 after setting USB_SS_PORT_LS_U0

[Kai-Heng Feng]

Like U3 case, xHCI spec doesn't specify the upper bound of U0 transition
time. The 20ms is not enough for some devices.

Intead of polling PLS or PLC, we can facilitate the port change event to
know that the link transits to U0 is completed.

While at it, seperate U0 and U3 case 

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/usb/host/xhci-hub.c  | 34 +++++++++++++++++++++-------------
 drivers/usb/host/xhci-mem.c  |  2 ++
 drivers/usb/host/xhci-ring.c |  1 +
 drivers/usb/host/xhci.h      |  1 +
 4 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index d3c5bcf76755..28a5c1c46079 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1297,7 +1297,23 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 					 wIndex, link_state);
 				goto error;
 			}
+
+			if (link_state == USB_SS_PORT_LS_U0) {
+				if ((temp & PORT_PLS_MASK) == XDEV_U0)
+					break;
+
+				reinit_completion(&bus_state->link_change_done[wIndex]);
+				xhci_set_link_state(xhci, ports[wIndex], USB_SS_PORT_LS_U0);
+				spin_unlock_irqrestore(&xhci->lock, flags);
+				if (!wait_for_completion_timeout(&bus_state->link_change_done[wIndex], msecs_to_jiffies(100)))
+					xhci_dbg(xhci, "missing U0 port change event for port %d-%d\n", hcd->self.busnum, wIndex + 1);
+				spin_lock_irqsave(&xhci->lock, flags);
+				temp = readl(ports[wIndex]->addr);
+				break;
+			}
+
 			if (link_state == USB_SS_PORT_LS_U3) {
+				int retries = 10;
 				slot_id = xhci_find_slot_id_by_port(hcd, xhci,
 						wIndex + 1);
 				if (slot_id) {
@@ -1308,26 +1324,18 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 					xhci_stop_device(xhci, slot_id, 1);
 					spin_lock_irqsave(&xhci->lock, flags);
 				}
-			}
-
-			xhci_set_link_state(xhci, ports[wIndex], link_state);
-
-			spin_unlock_irqrestore(&xhci->lock, flags);
-			if (link_state == USB_SS_PORT_LS_U3) {
-				int retries = 10;
-
+				xhci_set_link_state(xhci, ports[wIndex], USB_SS_PORT_LS_U3);
+				spin_unlock_irqrestore(&xhci->lock, flags);
 				while (retries--) {
 					msleep(10); /* wait device to enter */
 					temp = readl(ports[wIndex]->addr);
 					if ((temp & PORT_PLS_MASK) == XDEV_U3)
 						break;
 				}
-			}
-			spin_lock_irqsave(&xhci->lock, flags);
-
-			temp = readl(ports[wIndex]->addr);
-			if (link_state == USB_SS_PORT_LS_U3)
+				spin_lock_irqsave(&xhci->lock, flags);
+				temp = readl(ports[wIndex]->addr);
 				bus_state->suspended_ports |= 1 << wIndex;
+			}
 			break;
 		case USB_PORT_FEAT_POWER:
 			/*
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 3b1388fa2f36..aceb8c1af775 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -2531,6 +2531,8 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 		xhci->usb3_rhub.bus_state.resume_done[i] = 0;
 		/* Only the USB 2.0 completions will ever be used. */
 		init_completion(&xhci->usb2_rhub.bus_state.rexit_done[i]);
+		init_completion(&xhci->usb2_rhub.bus_state.link_change_done[i]);
+		init_completion(&xhci->usb3_rhub.bus_state.link_change_done[i]);
 	}
 
 	if (scratchpad_alloc(xhci, flags))
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index d23f7408c81f..4d0f8dab069a 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1677,6 +1677,7 @@ static void handle_port_status(struct xhci_hcd *xhci,
 	     (portsc & PORT_PLS_MASK) == XDEV_U1 ||
 	     (portsc & PORT_PLS_MASK) == XDEV_U2)) {
 		xhci_dbg(xhci, "resume SS port %d finished\n", port_id);
+		complete(&bus_state->link_change_done[hcd_portnum]);
 		/* We've just brought the device into U0/1/2 through either the
 		 * Resume state after a device remote wakeup, or through the
 		 * U3Exit state after a host-initiated resume.  If it's a device
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 13d8838cd552..b5d443ce0750 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1694,6 +1694,7 @@ struct xhci_bus_state {
 	/* Which ports are waiting on RExit to U0 transition. */
 	unsigned long		rexit_ports;
 	struct completion	rexit_done[USB_MAXCHILDREN];
+	struct completion	link_change_done[USB_MAXCHILDREN];
 };
 
 
-- 
2.17.1

[PATCH 3/3] USB: Disable LPM on WD19's Realtek Hub

[Kai-Heng Feng]

Realtek Hub (0bda:0x0487) used in Dell Dock WD19 sometimes drops off the
bus when bringing underlying ports from U3 to U0.

Disabling LPM on the hub during setting link state is not enough, so
let's disable LPM completely for this hub.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/usb/core/quirks.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index 6b6413073584..2fb7c1602280 100644
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -371,6 +371,9 @@ static const struct usb_device_id usb_quirk_list[] = {
 	{ USB_DEVICE(0x0b05, 0x17e0), .driver_info =
 			USB_QUIRK_IGNORE_REMOTE_WAKEUP },
 
+	/* Realtek hub in Dell WD19 (Type-C) */
+	{ USB_DEVICE(0x0bda, 0x0487), .driver_info = USB_QUIRK_NO_LPM },
+
 	/* Action Semiconductor flash disk */
 	{ USB_DEVICE(0x10d6, 0x2200), .driver_info =
 			USB_QUIRK_STRING_FETCH_255 },
-- 
2.17.1

Re: [PATCH v2 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3

[Kai-Heng Feng]

> On Feb 5, 2020, at 19:22, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
> 
> The xHCI spec doesn't specify the upper bound of U3 transition time. For
> some devices 20ms is not enough, so we need to make sure the link state
> is in U3 before further actions.
> 
> I've tried to use U3 Entry Capability by setting U3 Entry Enable in
> config register, however the port change event for U3 transition
> interrupts the system suspend process.
> 
> For now let's use the less ideal method by polling PLS.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

Please ignore this series. Some patches are missing changelog, will resend one.

Kai-Heng

> ---
> v2:
> - Remove some redundant debug messages.
> - Use msleep loop outside if spinlock to stop pegging CPU.
> 
> drivers/usb/host/xhci-hub.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> index 7a3a29e5e9d2..d3c5bcf76755 100644
> --- a/drivers/usb/host/xhci-hub.c
> +++ b/drivers/usb/host/xhci-hub.c
> @@ -1313,7 +1313,16 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
> 			xhci_set_link_state(xhci, ports[wIndex], link_state);
> 
> 			spin_unlock_irqrestore(&xhci->lock, flags);
> -			msleep(20); /* wait device to enter */
> +			if (link_state == USB_SS_PORT_LS_U3) {
> +				int retries = 10;
> +
> +				while (retries--) {
> +					msleep(10); /* wait device to enter */
> +					temp = readl(ports[wIndex]->addr);
> +					if ((temp & PORT_PLS_MASK) == XDEV_U3)
> +						break;
> +				}
> +			}
> 			spin_lock_irqsave(&xhci->lock, flags);
> 
> 			temp = readl(ports[wIndex]->addr);
> -- 
> 2.17.1
>