Cold plugged USB device was not detected on certain PCIe USB cards (like Inateck card connected to AM64 EVM or connected to J7200 EVM). Re-plugging the USB device always gets it enumerated. This issue was discussed in https://lore.kernel.org/r/772e4001-178e-4918-032c-6e625bdded24@xxxxxx and https://bugzilla.kernel.org/show_bug.cgi?id=214021 So the suggested solution is to register both root hubs along with the second hcd for xhci. RFC Patch series can be found at [1] v1 Patch series can be found at [3] v2 PATCH series can be found at [4] Changes from v2: 1) No Change (rebased to latest mainline kernel). V2 was reverted from mainline after it triggered a race in USB enumeration. Posting the patch (as attached in https://bugzilla.kernel.org/attachment.cgi?id=300800 after validating this fixes the issue using TI AM654 IDK EVM). Changes from RFC: 1) Mathias identified potential issues with the RFC patch [2] and suggested the solution to use HCD flags. This series implements it. Changes from v1: 1) Fixed code comments pointed out by Alan Stern 2) Renamed the HCD flag variable to "HCD_FLAG_DEFER_RH_REGISTER" from "HCD_FLAG_DEFER_PRI_RH_REGISTER" [1] -> https://lore.kernel.org/linux-usb/20210824105302.25382-1-kishon@xxxxxx/ [2] -> https://lore.kernel.org/linux-usb/06693934-28f2-d59e-b004-62cabd3f9e8e@xxxxxxxxxxxxxxx [3] -> https://lore.kernel.org/r/20210825105132.10420-1-kishon@xxxxxx [4] -> http://lore.kernel.org/r/20210826111426.751-1-kishon@xxxxxx Kishon Vijay Abraham I (2): usb: core: hcd: Add support for deferring roothub registration xhci: Set HCD flag to defer primary roothub registration drivers/usb/core/hcd.c | 29 +++++++++++++++++++++++------ drivers/usb/host/xhci.c | 2 ++ include/linux/usb/hcd.h | 2 ++ 3 files changed, 27 insertions(+), 6 deletions(-) -- 2.17.1
