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* [RESEND] [PATCH v2 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3
@ 2020-02-05 11:26 Kai-Heng Feng
  2020-02-05 11:26 ` [RESEND] [PATCH v2 2/3] xhci: Wait until link state trainsits to U0 after setting USB_SS_PORT_LS_U0 Kai-Heng Feng
  2020-02-05 11:26 ` [RESEND] [PATCH v2 3/3] USB: Disable LPM on WD19's Realtek Hub Kai-Heng Feng
  0 siblings, 2 replies; 6+ messages in thread
From: Kai-Heng Feng @ 2020-02-05 11:26 UTC (permalink / raw)
  To: mathias.nyman, gregkh, stern
  Cc: acelan.kao, linux-usb, linux-kernel, 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


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2020-03-11 14:15 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-02-05 11:26 [RESEND] [PATCH v2 1/3] xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3 Kai-Heng Feng
2020-02-05 11:26 ` [RESEND] [PATCH v2 2/3] xhci: Wait until link state trainsits to U0 after setting USB_SS_PORT_LS_U0 Kai-Heng Feng
2020-02-10 14:31   ` Mathias Nyman
2020-02-05 11:26 ` [RESEND] [PATCH v2 3/3] USB: Disable LPM on WD19's Realtek Hub Kai-Heng Feng
2020-03-11  3:32   ` Kai-Heng Feng
2020-03-11 14:15     ` Alan Stern

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