linux-kernel - Re: [PATCH 1/1] usb: dwc2: gadget: parity fix in isochronous mode

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Date:	Tue, 25 Aug 2015 21:51:36 +0000
From:	John Youn <John.Youn@...opsys.com>
To:	Scott Branden <sbranden@...adcom.com>,
	John Youn <John.Youn@...opsys.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"bcm-kernel-feedback-list@...adcom.com" 
	<bcm-kernel-feedback-list@...adcom.com>,
	Roman Bacik <rbacik@...adcom.com>
Subject: Re: [PATCH 1/1] usb: dwc2: gadget: parity fix in isochronous mode

On 8/18/2015 8:45 AM, Scott Branden wrote:
> From: Roman Bacik <rbacik@...adcom.com>
> 
> USB OTG driver in isochronous mode has to set the parity of the receiving
> microframe. The parity is set to even by default. This causes problems for
> an audio gadget, if the host starts transmitting on odd microframes.
> 
> This fix uses Incomplete Periodic Transfer interrupt to toggle between
> even and odd parity until the Transfer Complete interrupt is received.
> 
> Signed-off-by: Roman Bacik <rbacik@...adcom.com>
> Reviewed-by: Abhinav Ratna <aratna@...adcom.com>
> Reviewed-by: Srinath Mannam <srinath.mannam@...adcom.com>
> Reviewed-by: Scott Branden <sbranden@...adcom.com>
> Signed-off-by: Scott Branden <sbranden@...adcom.com>
> ---
>  drivers/usb/dwc2/core.h   |  1 +
>  drivers/usb/dwc2/gadget.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++-
>  drivers/usb/dwc2/hw.h     |  1 +
>  3 files changed, 49 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> index 0ed87620..954d1cd 100644
> --- a/drivers/usb/dwc2/core.h
> +++ b/drivers/usb/dwc2/core.h
> @@ -150,6 +150,7 @@ struct s3c_hsotg_ep {
>  	unsigned int            periodic:1;
>  	unsigned int            isochronous:1;
>  	unsigned int            send_zlp:1;
> +	unsigned int            parity_set:1;
>  
>  	char                    name[10];
>  };
> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> index 4d47b7c..28e4393 100644
> --- a/drivers/usb/dwc2/gadget.c
> +++ b/drivers/usb/dwc2/gadget.c
> @@ -1954,6 +1954,8 @@ static void s3c_hsotg_epint(struct dwc2_hsotg *hsotg, unsigned int idx,
>  		ints &= ~DXEPINT_XFERCOMPL;
>  
>  	if (ints & DXEPINT_XFERCOMPL) {
> +		if (hs_ep->isochronous && !hs_ep->parity_set)
> +			hs_ep->parity_set = 1;
>  		if (hs_ep->isochronous && hs_ep->interval == 1) {
>  			if (ctrl & DXEPCTL_EOFRNUM)
>  				ctrl |= DXEPCTL_SETEVENFR;
> @@ -2316,7 +2318,8 @@ void s3c_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
>  		GINTSTS_CONIDSTSCHNG | GINTSTS_USBRST |
>  		GINTSTS_RESETDET | GINTSTS_ENUMDONE |
>  		GINTSTS_OTGINT | GINTSTS_USBSUSP |
> -		GINTSTS_WKUPINT,
> +		GINTSTS_WKUPINT |
> +		GINTSTS_INCOMPL_SOIN | GINTSTS_INCOMPL_SOOUT,
>  		hsotg->regs + GINTMSK);
>  
>  	if (using_dma(hsotg))
> @@ -2581,6 +2584,48 @@ irq_retry:
>  		s3c_hsotg_dump(hsotg);
>  	}
>  
> +	if (gintsts & GINTSTS_INCOMPL_SOIN) {
> +		u32 idx;
> +		struct s3c_hsotg_ep *hs_ep;
> +
> +		dev_dbg(hsotg->dev, "%s: GINTSTS_INCOMPL_SOIN\n", __func__);
> +		for (idx = 1; idx < MAX_EPS_CHANNELS; idx++) {
> +			hs_ep = hsotg->eps_in[idx];
> +			if (hs_ep->isochronous && !hs_ep->parity_set) {
> +				u32 epctl_reg = DIEPCTL(idx);
> +				u32 ctrl = readl(hsotg->regs + epctl_reg);
> +
> +				if (ctrl & DXEPCTL_EOFRNUM)
> +					ctrl |= DXEPCTL_SETEVENFR;
> +				else
> +					ctrl |= DXEPCTL_SETODDFR;
> +				writel(ctrl, hsotg->regs + epctl_reg);
> +			}
> +		}
> +		writel(GINTSTS_INCOMPL_SOIN, hsotg->regs + GINTSTS);
> +	}
> +
> +	if (gintsts & GINTSTS_INCOMPL_SOOUT) {
> +		u32 idx;
> +		struct s3c_hsotg_ep *hs_ep;
> +
> +		dev_dbg(hsotg->dev, "%s: GINTSTS_INCOMPL_SOOUT\n", __func__);
> +		for (idx = 1; idx < MAX_EPS_CHANNELS; idx++) {
> +			hs_ep = hsotg->eps_out[idx];
> +			if (hs_ep->isochronous && !hs_ep->parity_set) {
> +				u32 epctl_reg = DOEPCTL(idx);
> +				u32 ctrl = readl(hsotg->regs + epctl_reg);
> +
> +				if (ctrl & DXEPCTL_EOFRNUM)
> +					ctrl |= DXEPCTL_SETEVENFR;
> +				else
> +					ctrl |= DXEPCTL_SETODDFR;
> +				writel(ctrl, hsotg->regs + epctl_reg);
> +			}
> +		}
> +		writel(GINTSTS_INCOMPL_SOOUT, hsotg->regs + GINTSTS);
> +	}
> +
>  	/*
>  	 * if we've had fifo events, we should try and go around the
>  	 * loop again to see if there's any point in returning yet.
> @@ -2667,6 +2712,7 @@ static int s3c_hsotg_ep_enable(struct usb_ep *ep,
>  	hs_ep->periodic = 0;
>  	hs_ep->halted = 0;
>  	hs_ep->interval = desc->bInterval;
> +	hs_ep->parity_set = 0;


I'm not quite sure what the parity_set flag does in this patch.
Shouldn't you be able to just toggle the even/odd frame when you
get the interrupt?

John


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