From: Greg KH <gregkh@linuxfoundation.org>
To: Wesley Cheng <quic_wcheng@quicinc.com>
Cc: Thinh.Nguyen@synopsys.com, linux-kernel@vger.kernel.org,
linux-usb@vger.kernel.org
Subject: Re: [PATCH v5 0/3] Avoid having pending end transfers on soft disconnect
Date: Thu, 20 Apr 2023 11:21:37 +0200 [thread overview]
Message-ID: <ZEEEIfqTKiM6CKAR@kroah.com> (raw)
In-Reply-To: <20230413195742.11821-1-quic_wcheng@quicinc.com>
On Thu, Apr 13, 2023 at 12:57:39PM -0700, Wesley Cheng wrote:
> In case there is a host which takes time to complete a SETUP transaction,
> during the soft disconnect sequence multiple DWC3 EPs will have their
> DWC3_EP_DELAY_STOP flag set w/o issuing the end transfer command. Once the
> controller halt sequence occurs, the soft disconnect is successful, and
> the subsequent soft connect will attempt to flush the pending end transfers.
>
> Soft disconnect sequence:
> dwc3_gadget_ep_disable name=ep8in flags=0x3009 direction=1
> dwc3_gadget_ep_disable name=ep4in flags=1 direction=1
> dwc3_gadget_ep_disable name=ep3out flags=1 direction=0
> usb_gadget_disconnect deactivated=0 connected=0 ret=0
>
> Soft connect bug:
> BUG: spinlock already unlocked on CPU
> spin_bug+0x0
> dwc3_remove_requests+0x278
> dwc3_ep0_out_start+0xb0
> __dwc3_gadget_start+0x25c
>
> The bug occurs due to the flush of the pending end transfers, as the gadget
> start routine is not held with a spinlock. However, if the DWC3_EP_DELAY_STOP
> is set, it will call the giveback API, which attempts to unlock the dwc->lock.
> Ideally, the DWC3 gadget should not have pending end transfers on a soft
> connect, so fix this by:
>
> 1. Re-locating the SETUP phase check after stop active transfers, since
> that is where the DWC3_EP_DELAY_STOP is potentially set. This also allows
> for handling of a host that may be unresponsive by using the completion
> timeout to trigger the stall and restart for EP0.
>
> 2. Do not call gadget stop until the poll for controller halt is
> completed. DEVTEN is cleared as part of gadget stop, so the intention to
> allow ep0 events to continue while waiting for controller halt is not
> happening.
Only patch 1 applied, can you rebase the rest and resend with the acks
applied?
thanks,
greg k-h
prev parent reply other threads:[~2023-04-20 9:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-13 19:57 [PATCH v5 0/3] Avoid having pending end transfers on soft disconnect Wesley Cheng
2023-04-13 19:57 ` [PATCH v5 1/3] usb: dwc3: gadget: Stall and restart EP0 if host is unresponsive Wesley Cheng
2023-04-18 1:46 ` Thinh Nguyen
2023-04-13 19:57 ` [PATCH v5 2/3] usb: dwc3: gadget: Execute gadget stop after halting the controller Wesley Cheng
2023-04-13 19:57 ` [PATCH v5 3/3] usb: dwc3: gadget: Refactor EP0 forced stall/restart into a separate API Wesley Cheng
2023-04-18 1:47 ` Thinh Nguyen
2023-04-20 9:21 ` Greg KH [this message]
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