linux-kernel - RE: [PATCH] usb: dwc3: gadget: don't remove the request if bus-expired

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Date:   Mon, 21 Jan 2019 11:03:40 +0200
From:   Felipe Balbi <felipe.balbi@...ux.intel.com>
To:     "Zengtao \(B\)" <prime.zeng@...ilicon.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb\@vger.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] usb: dwc3: gadget: don't remove the request if bus-expired


Hi,

"Zengtao (B)" <prime.zeng@...ilicon.com> writes:
>>-----Original Message-----
>>From: Felipe Balbi [mailto:felipe.balbi@...ux.intel.com]
>>Sent: Monday, January 14, 2019 4:13 PM
>>To: Zengtao (B) <prime.zeng@...ilicon.com>
>>Cc: Zengtao (B) <prime.zeng@...ilicon.com>; Greg Kroah-Hartman
>><gregkh@...uxfoundation.org>; linux-usb@...r.kernel.org;
>>linux-kernel@...r.kernel.org
>>Subject: Re: [PATCH] usb: dwc3: gadget: don't remove the request if
>>bus-expired
>>
>>* PGP Signed by an unknown key
>>
>>
>>Hi,
>>
>>Zeng Tao <prime.zeng@...ilicon.com> writes:
>>> We have already returned EAGAIN for bus-expiry, and it's designed to
>>> start with a future Frame number and start the transfer again. So we
>>> should not remove the request for that case.
>>>
>>> Signed-off-by: Zeng Tao <prime.zeng@...ilicon.com>
>>
>>Do we need a Fixes tag here? How about Cc stable? Can you share
>>tracepoints exposing the problem?
>>
>
> I am not sure that we need to Fixes tag, it's not related to any single patch, but
> there is definitely something wrong, after rethinking it again, I found that there
> are still some problems for this patch, for the reties inside the driver, we should not
> remove the request, but if we return -EAGAIN to the gadget layer, we should because
> the gadget will requeue the request again if we return -EAGAIN.
>
> Any suggestions. 

Well, that needs to be patched, sure. I'm just saying that we need to
blame a patch that was incomplete so we know which stable releases need
this. Perhaps the patch at fault here was my patch adding the retry
method for isoc transfers.

-- 
balbi

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