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Subject: Re: [PATCH] Revert "usb: dwc3: gadget: drop unnecessary loop when
 cleaning up TRBs"
To: ville.syrjala@linux.intel.com, Felipe Balbi <balbi@ti.com>
References: <1441039708-2504-1-git-send-email-ville.syrjala@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org, stable@vger.kernel.org
From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Message-ID: <55E4A92C.70407@cogentembedded.com>
Date: Mon, 31 Aug 2015 22:21:16 +0300
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Hello.

On 08/31/2015 07:48 PM, ville.syrjala@linux.intel.com wrote:

> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> This reverts commit 8f2c9544aba636134303105ecb164190a39dece4.
>
> As it breaks g_ether on my Baytrail FFRD8 device. Everything starts out
> fine, but after a bit of data has been transferred it just stops
> flowing.
>
> Note that I do get a bunch of these "NOHZ: local_softirq_pending 08"
> when booting the machine, but I'm not really sure if they're related
> to this problem.
>
> Cc: Felipe Balbi <balbi@ti.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
> Cc: stable@vger.kernel.org
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>   drivers/usb/dwc3/gadget.c | 37 +++++++++++++++++++++----------------
>   1 file changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 333a7c0..9a5de54 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1859,27 +1859,32 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
>   	unsigned int		i;
>   	int			ret;
>
> -	req = next_request(&dep->req_queued);
> -	if (!req) {
> -		WARN_ON_ONCE(1);
> -		return 1;
> -	}
> -	i = 0;
>   	do {
> -		slot = req->start_slot + i;
> -		if ((slot == DWC3_TRB_NUM - 1) &&
> +		req = next_request(&dep->req_queued);
> +		if (!req) {
> +			WARN_ON_ONCE(1);
> +			return 1;
> +		}
> +		i = 0;
> +		do {
> +			slot = req->start_slot + i;
> +			if ((slot == DWC3_TRB_NUM - 1) &&
>   				usb_endpoint_xfer_isoc(dep->endpoint.desc))
> -			slot++;
> -		slot %= DWC3_TRB_NUM;
> -		trb = &dep->trb_pool[slot];
> +				slot++;
> +			slot %= DWC3_TRB_NUM;
> +			trb = &dep->trb_pool[slot];
> +
> +			ret = __dwc3_cleanup_done_trbs(dwc, dep, req, trb,
> +					event, status);
> +			if (ret)
> +				break;
> +		}while (++i < req->request.num_mapped_sgs);

    Space needed after }. And this *do {} while* loop seems replaceable with 
*foor* loop...

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