linux-kernel - [PATCH RESEND v2 2/2] usb: xhci-mtk: fix bandwidth release issue

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Date:   Fri, 19 Aug 2022 16:05:56 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     Mathias Nyman <mathias.nyman@...el.com>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <linux-usb@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        "Eddie Hung" <eddie.hung@...iatek.com>
Subject: [PATCH RESEND v2 2/2] usb: xhci-mtk: fix bandwidth release issue

This happens when @udev->reset_resume is set to true, when usb resume,
the flow as below:
  - hub_resume
    - usb_disable_interface
      - usb_disable_endpoint
        - usb_hcd_disable_endpoint
          - xhci_endpoint_disable  // it set @ep->hcpriv to NULL

Then when reset usb device, it will drop allocated endpoints,
the flow as below:
  - usb_reset_and_verify_device
    - usb_hcd_alloc_bandwidth
      - xhci_mtk_drop_ep

but @ep->hcpriv is already set to NULL, the bandwidth will be not
released anymore.

Due to the added endponts are stored in hash table, we can drop the check
of @ep->hcpriv.

Fixes: 4ce186665e7c ("usb: xhci-mtk: Do not use xhci's virt_dev in drop_endpoint")
Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
---
v2: add comment
---
 drivers/usb/host/xhci-mtk-sch.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/xhci-mtk-sch.c b/drivers/usb/host/xhci-mtk-sch.c
index a17bc584ee99..579899eb24c1 100644
--- a/drivers/usb/host/xhci-mtk-sch.c
+++ b/drivers/usb/host/xhci-mtk-sch.c
@@ -764,8 +764,8 @@ int xhci_mtk_drop_ep(struct usb_hcd *hcd, struct usb_device *udev,
 	if (ret)
 		return ret;
 
-	if (ep->hcpriv)
-		drop_ep_quirk(hcd, udev, ep);
+	/* needn't check @ep->hcpriv, xhci_endpoint_disable set it NULL */
+	drop_ep_quirk(hcd, udev, ep);
 
 	return 0;
 }
-- 
2.18.0