• Anurag Kumar Vulisha's avatar
    usb: dwc3: gadget: Check for IOC/LST bit in TRB->ctrl fields · 5ee85897
    Anurag Kumar Vulisha authored
    The current code in dwc3_gadget_ep_reclaim_completed_trb() will
    check for IOC/LST bit in the event->status and returns if
    IOC/LST bit is set. This logic doesn't work if multiple TRBs
    are queued per request and the IOC/LST bit is set on the last
    TRB of that request.
    
    Consider an example where a queued request has multiple queued
    TRBs and IOC/LST bit is set only for the last TRB. In this case,
    the core generates XferComplete/XferInProgress events only for
    the last TRB (since IOC/LST are set only for the last TRB). As
    per the logic in dwc3_gadget_ep_reclaim_completed_trb()
    event->status is checked for IOC/LST bit and returns on the
    first TRB. This leaves the remaining TRBs left unhandled.
    
    Similarly, if the gadget function enqueues an unaligned request
    with sglist already in it, it should fail the same way, since we
    will append another TRB to something that already uses more than
    one TRB.
    
    To aviod this, this patch changes the code to check for IOC/LST
    bits in TRB->ctrl instead.
    
    At a practical level, this patch resolves USB transfer stalls seen
    with adb on dwc3 based HiKey960 after functionfs gadget added
    scatter-gather support around v4.20.
    
    Cc: Felipe Balbi <balbi@kernel.org>
    Cc: Yang Fei <fei.yang@intel.com>
    Cc: Thinh Nguyen <thinhn@synopsys.com>
    Cc: Tejas Joglekar <tejas.joglekar@synopsys.com>
    Cc: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
    Cc: Jack Pham <jackp@codeaurora.org>
    Cc: Todd Kjos <tkjos@google.com>
    Cc: Greg KH <gregkh@linuxfoundation.org>
    Cc: Linux USB List <linux-usb@vger.kernel.org>
    Cc: stable <stable@vger.kernel.org>
    Tested-by: default avatarTejas Joglekar <tejas.joglekar@synopsys.com>
    Reviewed-by: default avatarThinh Nguyen <thinhn@synopsys.com>
    Signed-off-by: default avatarAnurag Kumar Vulisha <anurag.kumar.vulisha@xilinx.com>
    [jstultz: forward ported to mainline, reworded commit log, reworked
     to only check trb->ctrl as suggested by Felipe]
    Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
    Signed-off-by: default avatarFelipe Balbi <balbi@kernel.org>
    5ee85897
gadget.c 87.3 KB