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From:   John Stultz <john.stultz@linaro.org>
To:     lkml <linux-kernel@vger.kernel.org>
Cc:     John Stultz <john.stultz@linaro.org>,
        YongQin Liu <yongqin.liu@linaro.org>,
        Anurag Kumar Vulisha <anurag.kumar.vulisha@xilinx.com>,
        Yang Fei <fei.yang@intel.com>,
        Thinh Nguyen <thinhn@synopsys.com>,
        Tejas Joglekar <tejas.joglekar@synopsys.com>,
        Andrzej Pietrasiewicz <andrzej.p@collabora.com>,
        Jack Pham <jackp@codeaurora.org>, Josh Gao <jmgao@google.com>,
        Todd Kjos <tkjos@google.com>, Felipe Balbi <balbi@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-usb@vger.kernel.org, stable@vger.kernel.org
Subject: [PATCH] dwc3: Remove check for HWO flag in dwc3_gadget_ep_reclaim_trb_sg()
Date:   Thu, 23 Apr 2020 22:08:49 +0000
Message-Id: <20200423220849.30280-1-john.stultz@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The check for the HWO flag in dwc3_gadget_ep_reclaim_trb_sg()
causes us to break out of the loop before we call
dwc3_gadget_ep_reclaim_completed_trb(), which is what likely
should be clearing the HWO flag.

This can cause odd behavior where we never reclaim all the trbs
in the sg list, so we never call giveback on a usb req, and that
will causes transfer stalls.

This effectively resovles the adb stalls seen on HiKey960
after userland changes started only using AIO in adbd.

Cc: YongQin Liu <yongqin.liu@linaro.org>
Cc: Anurag Kumar Vulisha <anurag.kumar.vulisha@xilinx.com>
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: Josh Gao <jmgao@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Cc: stable@vger.kernel.org #4.20+
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 drivers/usb/dwc3/gadget.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 4d3c79d90a6e..2a26d33520ce 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2457,9 +2457,6 @@ static int dwc3_gadget_ep_reclaim_trb_sg(struct dwc3_ep *dep,
 	for_each_sg(sg, s, pending, i) {
 		trb = &dep->trb_pool[dep->trb_dequeue];
 
-		if (trb->ctrl & DWC3_TRB_CTRL_HWO)
-			break;
-
 		req->sg = sg_next(s);
 		req->num_pending_sgs--;
 
-- 
2.17.1