linux-kernel - Re: [PATCH v2 4/5] usb: dwc3: Allow end transfer commands to be sent during soft disconnect

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Message-ID: <5d0cf380-e045-fcec-639f-ac2f6a187ca8@synopsys.com>
Date:   Thu, 21 Jul 2022 22:20:40 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Wesley Cheng <quic_wcheng@...cinc.com>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "quic_jackp@...cinc.com" <quic_jackp@...cinc.com>
Subject: Re: [PATCH v2 4/5] usb: dwc3: Allow end transfer commands to be sent
 during soft disconnect

On 7/21/2022, Wesley Cheng wrote:
> Hi Thinh,
>
> On 7/21/2022 3:08 PM, Thinh Nguyen wrote:
>> Hi Wesley,
>>
>> On 7/12/2022, Wesley Cheng wrote:
>>> If soft disconnect is in progress, allow the endxfer command to be 
>>> sent,
>>> without this, there is an issue where the stop active transfer call
>>> (during pullup disable) wouldn't actually issue the endxfer command,
>>> while clearing the DEP flag.
>>>
>>> In addition, if the DWC3_EP_DELAY_STOP flag was set before soft 
>>> disconnect
>>> started (i.e. from the dequeue path), ensure that when the EP0 
>>> transaction
>>> completes during soft disconnect, to issue the endxfer with the force
>>> parameter set, as it does not expect a command complete event.
>>>
>>> Fixes: e4cf6580ac740 ("usb: dwc3: gadget: Wait for ep0 xfers to 
>>> complete during dequeue")
>>> Suggested-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
>>> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
>>> ---
>>> Link:
>>> https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/1a1a5485-790e-79ce-f5a6-1e96d9b49a47@synopsys.com/__;!!A4F2R9G_pg!cXW2TlALYWnXNPg-NoMFUrQ8K1egEZiQizZ5CA1DOM1Gcw4tfOULy-_2eMGvL8pQPte5dScFON-0wxH2eXu8ijEQUbs$
>>>
>>>    drivers/usb/dwc3/ep0.c    | 3 +--
>>>    drivers/usb/dwc3/gadget.c | 5 ++++-
>>>    2 files changed, 5 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
>>> index 506ef717fdc0..5851b0e9db0a 100644
>>> --- a/drivers/usb/dwc3/ep0.c
>>> +++ b/drivers/usb/dwc3/ep0.c
>>> @@ -290,8 +290,7 @@ void dwc3_ep0_out_start(struct dwc3 *dwc)
>>>            if (!(dwc3_ep->flags & DWC3_EP_DELAY_STOP))
>>>                continue;
>>>    -        dwc3_ep->flags &= ~DWC3_EP_DELAY_STOP;
>>
>> If we don't clear this flag here,
>>
>
> This is why I added the dwc->connected argument to control the 
> "interrupt" argument.
>
>>> - dwc3_stop_active_transfer(dwc3_ep, true, true);
>>> +        dwc3_stop_active_transfer(dwc3_ep, true, dwc->connected);
>>>        }
>>>    }
>>>    diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>> index ee85b773e3fe..41b7007358de 100644
>>> --- a/drivers/usb/dwc3/gadget.c
>>> +++ b/drivers/usb/dwc3/gadget.c
>>> @@ -1693,6 +1693,7 @@ static int __dwc3_stop_active_transfer(struct 
>>> dwc3_ep *dep, bool force, bool int
>>>            dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
>>>        else if (!ret)
>>>            dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
>>> +    dep->flags &= ~DWC3_EP_DELAY_STOP;
>>>           return ret;
>>>    }
>>> @@ -3686,8 +3687,10 @@ void dwc3_stop_active_transfer(struct dwc3_ep 
>>> *dep, bool force,
>>>        if (dep->number <= 1 && dwc->ep0state != EP0_DATA_PHASE)
>>>            return;
>>>    +    if (interrupt && (dep->flags & DWC3_EP_DELAY_STOP))
>>> +        return;
>>> +
>>
>> then it may not go through here. I think I made this same mistake in my
>> previous suggestion.
>>
>
> Since dwc->connected is set to FALSE before we call stop active 
> transfers, if we ever run into a situation where delayed stop is set 
> already, then it should go through.
>

Then the check for request dequeue that we did previously will not work 
anymore.

BR,
Thinh