From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> commit 33e321586e37b642ad10594b9ef25a613555cd08 upstream. After xHC controller is started, either in probe or resume, it can take a while before any of the connected usb devices are visible to the roothub due to link training. It's possible xhci driver loads, sees no acivity and suspends the host before the USB device is visible. In one testcase with a hotplugged xHC controller the host finally detected the connected USB device and generated a wake 500ms after host initial start. If hosts didn't suspend the device duringe training it probablty wouldn't take up to 500ms to detect it, but looking at specs reveal USB3 link training has a couple long timeout values, such as 120ms RxDetectQuietTimeout, and 360ms PollingLFPSTimeout. So Add a 500ms grace period that keeps polling the roothub for 500ms after start, preventing runtime suspend until USB devices are detected. Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220825150840.132216-3-mathias.nyman@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/host/xhci-hub.c | 11 +++++++++++ drivers/usb/host/xhci.c | 4 +++- drivers/usb/host/xhci.h | 2 +- 3 files changed, 15 insertions(+), 2 deletions(-) --- a/drivers/usb/host/xhci-hub.c +++ b/drivers/usb/host/xhci-hub.c @@ -1561,6 +1561,17 @@ int xhci_hub_status_data(struct usb_hcd status = bus_state->resuming_ports; + /* + * SS devices are only visible to roothub after link training completes. + * Keep polling roothubs for a grace period after xHC start + */ + if (xhci->run_graceperiod) { + if (time_before(jiffies, xhci->run_graceperiod)) + status = 1; + else + xhci->run_graceperiod = 0; + } + mask = PORT_CSC | PORT_PEC | PORT_OCC | PORT_PLC | PORT_WRC | PORT_CEC; /* For each port, did anything change? If so, set that bit in buf. */ --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -149,9 +149,11 @@ int xhci_start(struct xhci_hcd *xhci) xhci_err(xhci, "Host took too long to start, " "waited %u microseconds.\n", XHCI_MAX_HALT_USEC); - if (!ret) + if (!ret) { /* clear state flags. Including dying, halted or removing */ xhci->xhc_state = 0; + xhci->run_graceperiod = jiffies + msecs_to_jiffies(500); + } return ret; } --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1816,7 +1816,7 @@ struct xhci_hcd { /* Host controller watchdog timer structures */ unsigned int xhc_state; - + unsigned long run_graceperiod; u32 command; struct s3_save s3; /* Host controller is dying - not responding to commands. "I'm not dead yet!"
