Hi Mathias,
On 9/11/2023 6:50 AM, Mathias Nyman wrote:
On 1.9.2023 3.15, Wesley Cheng wrote:
There is a 120ms delay implemented for allowing the XHCI host
controller to
detect a U3 wakeup pulse. The intention is to wait for the device to
retry
the wakeup event if the USB3 PORTSC doesn't reflect the RESUME link
status
by the time it is checked. As per the USB3 specification:
tU3WakeupRetryDelay ("Table 7-12. LTSSM State Transition Timeouts")
This would allow the XHCI resume sequence to determine if the root hub
needs to be also resumed. However, in case there is no device connected,
or if there is only a HSUSB device connected, this delay would still
affect
the overall resume timing.
Since this delay is solely for detecting U3 wake events (USB3 specific)
then ignore this delay for the disconnected case and the HSUSB connected
only case.
Thanks, makes sense
Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
---
drivers/usb/host/xhci.c | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index e1b1b64a0723..640db6a4e686 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -805,6 +805,24 @@ static void xhci_disable_hub_port_wake(struct
xhci_hcd *xhci,
spin_unlock_irqrestore(&xhci->lock, flags);
}
+static bool xhci_usb3_dev_connected(struct xhci_hcd *xhci)
+{
+ struct xhci_port **ports;
+ int port_index;
+ u32 portsc;
+
+ port_index = xhci->usb3_rhub.num_ports;
+ ports = xhci->usb3_rhub.ports;
+
+ while (port_index--) {
+ portsc = readl(ports[port_index]->addr);
+ if (portsc & (portsc & PORT_CONNECT))
+ return true;
+ }
+
+ return false;
+}
+
This is one way, but we can probably avoid re-reading all the usb3
portsc registers
by checking if any bit is set in either:
// bitfield, set if xhci usb3 port neatly set to U3 with a hub request
xhci->usb3_rhub.bus_state.suspended_ports
// bitfield, set if xhci usb3 port is forced to U3 during xhci suspend.
xhci->usb3_rhub.bus_state.bus_suspended
But haven't checked this works in all corner cases.
Thanks for the suggestion. I think I also looked at seeing if we could
use the suspended_ports param, and it was missing one of the use cases
we had. I haven't thought on combining it with the bus_suspend param
also to see if it could work. Let me give it a try, and I'll get back
to you.
Thanks
Wesley Cheng
