linux-kernel - Re: [PATCH] usb: dwc3: gadget: Fix ISO transfer performance

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Date:   Wed, 17 May 2017 10:44:17 +0300
From:   Roger Quadros <rogerq@...com>
To:     <balbi@...nel.org>
CC:     <nsekhar@...com>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc3: gadget: Fix ISO transfer performance

Hi Felipe,

On 21/04/17 15:58, Roger Quadros wrote:
> Commit 08a36b543803 ("usb: dwc3: gadget: simplify __dwc3_gadget_ep_queue()")
> caused a small change in the way ISO transfer is handled in the case
> when XferInProgress event happens on Isoc EP with an active transfer.
> This caused a performance degradation of 50%. e.g. using g_webcam on DUT
> and luvcview on host the video frame rate dropped from 16fps to 8fps
> @high-speed.
> 
> Make the ISO transfer handling equivalent to that prior to that commit
> to get back the original ISO performance numbers.
> 
> Fixes: 08a36b543803 ("usb: dwc3: gadget: simplify __dwc3_gadget_ep_queue()")
> Signed-off-by: Roger Quadros <rogerq@...com>

Any comments?

> ---
>  drivers/usb/dwc3/gadget.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 0d75158..8f71ccc 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1245,14 +1245,24 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
>  				__dwc3_gadget_start_isoc(dwc, dep, cur_uf);
>  				dep->flags &= ~DWC3_EP_PENDING_REQUEST;
>  			}
> +			return 0;
>  		}
> -		return 0;
> +
> +		if ((dep->flags & DWC3_EP_BUSY) &&
> +		    !(dep->flags & DWC3_EP_MISSED_ISOC)) {
> +			WARN_ON_ONCE(!dep->resource_index);
> +			ret = __dwc3_gadget_kick_transfer(dep,
> +							  dep->resource_index);
> +		}
> +
> +		goto out;
>  	}
>  
>  	if (!dwc3_calc_trbs_left(dep))
>  		return 0;
>  
>  	ret = __dwc3_gadget_kick_transfer(dep, 0);
> +out:
>  	if (ret == -EBUSY)
>  		ret = 0;
>  
> 

-- 
cheers,
-roger