> On Feb 5, 2020, at 19:22, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
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
>
