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xhci: Ensure link state is U3 after setting USB_SS_PORT_LS_U3 

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.

[use usleep_range(), and shorten the delay time while polling -Mathias]
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200312144517.1593-7-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kai-Heng Feng 2020-03-12 16:45:14 +02:00 committed by Greg Kroah-Hartman
parent cbb23d5572
commit eb002726fa
1 changed files with 10 additions and 1 deletions
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11
drivers/usb/host/xhci-hub.c
View File

@ -1324,7 +1324,16 @@ 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 = 16;
while (retries--) {
usleep_range(4000, 8000);
temp = readl(ports[wIndex]->addr);
if ((temp & PORT_PLS_MASK) == XDEV_U3)
break;
}
}
spin_lock_irqsave(&xhci->lock, flags);
temp = readl(ports[wIndex]->addr);