linux-kernel - Re: [PATCH v2 1/5] usb: dwc2: gadget: use ep->fifo

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Date:	Thu, 4 Feb 2016 12:25:08 +0000
From:	Vahram Aharonyan <Vahram.Aharonyan@...opsys.com>
To:	Robert Baldyga <r.baldyga@...sung.com>,
	"balbi@...com" <balbi@...com>,
	"John.Youn@...opsys.com" <John.Youn@...opsys.com>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
	"b.zolnierkie@...sung.com" <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v2 1/5] usb: dwc2: gadget: use ep->fifo_index in context
 of FIFO registers

On 2/3/2016 3:40 PM, Robert Baldyga wrote:
> In context of FIFO registers we use ep->fifo_index instead of ep->index.
> 
> Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>
> ---
>  drivers/usb/dwc2/gadget.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> index 422ab7d..0d0f6fe 100644
> --- a/drivers/usb/dwc2/gadget.c
> +++ b/drivers/usb/dwc2/gadget.c
> @@ -369,7 +369,8 @@ static int dwc2_hsotg_write_fifo(struct dwc2_hsotg *hsotg,
>  			return -ENOSPC;
>  		}
>  	} else if (hsotg->dedicated_fifos && hs_ep->index != 0) {
> -		can_write = dwc2_readl(hsotg->regs + DTXFSTS(hs_ep->index));
> +		can_write = dwc2_readl(hsotg->regs +
> +				DTXFSTS(hs_ep->fifo_index));
>  
>  		can_write &= 0xffff;
>  		can_write *= 4;
> @@ -2172,7 +2173,7 @@ static void kill_all_requests(struct dwc2_hsotg *hsotg,
>  
>  	if (!hsotg->dedicated_fifos)
>  		return;
> -	size = (dwc2_readl(hsotg->regs + DTXFSTS(ep->index)) & 0xffff) * 4;
> +	size = (dwc2_readl(hsotg->regs + DTXFSTS(ep->fifo_index)) & 0xffff) * 4;
>  	if (size < ep->fifo_size)
>  		dwc2_hsotg_txfifo_flush(hsotg, ep->fifo_index);
>  }
> 

Hi Robert,

DTXFSTS register is linked with endpoint, not FIFO - it contains information about how much space is used in the FIFO assigned to the endpoint. Changing ep->index to ep->fifo_index will work, if FIFO number assigned to that endpoint coincides with ep->index. For example, TX FIFO #1 has been assigned to EP 1 In. If TX FIFO #2 was assigned to EP #1, then with this change DTXFSTS[2] will be used instead of DTXFSTS[1] for EP #1.

Thanks,
Vahram.