Subject: Re: [PATCH v2] usb/fsl_udc: fix dequeuing a request in progress

From: Peter Chen <[email-masked]>
Date: Thu, 24 Nov 2011 09:56:20 +0800

On Wed, Nov 23, 2011 at 08:12:56PM +0800, Li Yang wrote:
> The original implementation of dequeuing a request in progress
> is not correct.  Change to use a correct process and also clean
> up the related functions a little bit.
> 
> Signed-off-by: Li Yang <[email-masked]>
> Cc: Peter Chen <[email-masked]>
> ---
>  drivers/usb/gadget/fsl_udc_core.c |   68 +++++++++++++++++-------------------
>  drivers/usb/gadget/fsl_usb2_udc.h |   10 +++++
>  2 files changed, 42 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/usb/gadget/fsl_udc_core.c b/drivers/usb/gadget/fsl_udc_core.c
> index b2c44e1..cc704dc 100644
> --- a/drivers/usb/gadget/fsl_udc_core.c
> +++ b/drivers/usb/gadget/fsl_udc_core.c
> @@ -696,12 +696,31 @@ static void fsl_free_request(struct usb_ep *_ep, struct usb_request *_req)
>  		kfree(req);
>  }
>  
> -/*-------------------------------------------------------------------------*/
> +/* Actually add a dTD chain to an empty dQH and let go */
> +static void fsl_prime_ep(struct fsl_ep *ep, struct ep_td_struct *td)
> +{
> +	struct ep_queue_head *qh = get_qh_by_ep(ep);
> +
> +	/* Write dQH next pointer and terminate bit to 0 */
> +	qh->next_dtd_ptr = cpu_to_hc32(td->td_dma
> +			& EP_QUEUE_HEAD_NEXT_POINTER_MASK);
> +
> +	/* Clear active and halt bit */
> +	qh->size_ioc_int_sts &= cpu_to_hc32(~(EP_QUEUE_HEAD_STATUS_ACTIVE
> +					| EP_QUEUE_HEAD_STATUS_HALT));
> +
> +	/* Ensure that updates to the QH will occur before priming. */
> +	wmb();
> +
> +	/* Prime endpoint by writing correct bit to ENDPTPRIME */
> +	fsl_writel(ep_is_in(ep) ? (1 << (ep_index(ep) + 16))
> +			: (1 << (ep_index(ep))), &dr_regs->endpointprime);
> +}
> +
> +/* Add dTD chain to the dQH of an EP */
>  static void fsl_queue_td(struct fsl_ep *ep, struct fsl_req *req)
>  {
> -	int i = ep_index(ep) * 2 + ep_is_in(ep);
>  	u32 temp, bitmask, tmp_stat;
> -	struct ep_queue_head *dQH = &ep->udc->ep_qh[i];
>  
>  	/* VDBG("QH addr Register 0x%8x", dr_regs->endpointlistaddr);
>  	VDBG("ep_qh[%d] addr is 0x%8x", i, (u32)&(ep->udc->ep_qh[i])); */
> @@ -719,7 +738,7 @@ static void fsl_queue_td(struct fsl_ep *ep, struct fsl_req *req)
>  			cpu_to_hc32(req->head->td_dma & DTD_ADDR_MASK);
>  		/* Read prime bit, if 1 goto done */
>  		if (fsl_readl(&dr_regs->endpointprime) & bitmask)
> -			goto out;
> +			return;
>  
>  		do {
>  			/* Set ATDTW bit in USBCMD */
> @@ -736,28 +755,10 @@ static void fsl_queue_td(struct fsl_ep *ep, struct fsl_req *req)
>  		fsl_writel(temp & ~USB_CMD_ATDTW, &dr_regs->usbcmd);
>  
>  		if (tmp_stat)
> -			goto out;
> +			return;
>  	}
>  
> -	/* Write dQH next pointer and terminate bit to 0 */
> -	temp = req->head->td_dma & EP_QUEUE_HEAD_NEXT_POINTER_MASK;
> -	dQH->next_dtd_ptr = cpu_to_hc32(temp);
> -
> -	/* Clear active and halt bit */
> -	temp = cpu_to_hc32(~(EP_QUEUE_HEAD_STATUS_ACTIVE
> -			| EP_QUEUE_HEAD_STATUS_HALT));
> -	dQH->size_ioc_int_sts &= temp;
> -
> -	/* Ensure that updates to the QH will occur before priming. */
> -	wmb();
> -
> -	/* Prime endpoint by writing 1 to ENDPTPRIME */
> -	temp = ep_is_in(ep)
> -		? (1 << (ep_index(ep) + 16))
> -		: (1 << (ep_index(ep)));
> -	fsl_writel(temp, &dr_regs->endpointprime);
> -out:
> -	return;
> +	fsl_prime_ep(ep, req->head);
>  }
>  
>  /* Fill in the dTD structure
> @@ -973,25 +974,20 @@ static int fsl_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
>  
>  		/* The request isn't the last request in this ep queue */
>  		if (req->queue.next != &ep->queue) {
> -			struct ep_queue_head *qh;
>  			struct fsl_req *next_req;
>  
> -			qh = ep->qh;
>  			next_req = list_entry(req->queue.next, struct fsl_req,
>  					queue);
>  
> -			/* Point the QH to the first TD of next request */
> -			fsl_writel((u32) next_req->head, &qh->curr_dtd_ptr);
> +			/* prime with dTD of next request */
> +			fsl_prime_ep(ep, next_req->head);
>  		}
> -
> -		/* The request hasn't been processed, patch up the TD chain */
> +	/* The request hasn't been processed, patch up the TD chain */
>  	} else {
>  		struct fsl_req *prev_req;
>  
>  		prev_req = list_entry(req->queue.prev, struct fsl_req, queue);
> -		fsl_writel(fsl_readl(&req->tail->next_td_ptr),
> -				&prev_req->tail->next_td_ptr);
> -
> +		prev_req->tail->next_td_ptr = req->tail->next_td_ptr;
>  	}
>  
>  	done(ep, req, -ECONNRESET);
> @@ -1068,7 +1064,7 @@ static int fsl_ep_fifo_status(struct usb_ep *_ep)
>  	struct fsl_udc *udc;
>  	int size = 0;
>  	u32 bitmask;
> -	struct ep_queue_head *d_qh;
> +	struct ep_queue_head *qh;
>  
>  	ep = container_of(_ep, struct fsl_ep, ep);
>  	if (!_ep || (!ep->desc && ep_index(ep) != 0))
> @@ -1079,13 +1075,13 @@ static int fsl_ep_fifo_status(struct usb_ep *_ep)
>  	if (!udc->driver || udc->gadget.speed == USB_SPEED_UNKNOWN)
>  		return -ESHUTDOWN;
>  
> -	d_qh = &ep->udc->ep_qh[ep_index(ep) * 2 + ep_is_in(ep)];
> +	qh = get_qh_by_ep(ep);
>  
>  	bitmask = (ep_is_in(ep)) ? (1 << (ep_index(ep) + 16)) :
>  	    (1 << (ep_index(ep)));
>  
>  	if (fsl_readl(&dr_regs->endptstatus) & bitmask)
> -		size = (d_qh->size_ioc_int_sts & DTD_PACKET_SIZE)
> +		size = (qh->size_ioc_int_sts & DTD_PACKET_SIZE)
>  		    >> DTD_LENGTH_BIT_POS;
>  
>  	pr_debug("%s %u\n", __func__, size);
> diff --git a/drivers/usb/gadget/fsl_usb2_udc.h b/drivers/usb/gadget/fsl_usb2_udc.h
> index 1d51be8..f781f5d 100644
> --- a/drivers/usb/gadget/fsl_usb2_udc.h
> +++ b/drivers/usb/gadget/fsl_usb2_udc.h
> @@ -569,6 +569,16 @@ static void dump_msg(const char *label, const u8 * buf, unsigned int length)
>  					* 2 + ((windex & USB_DIR_IN) ? 1 : 0))
>  #define get_pipe_by_ep(EP)	(ep_index(EP) * 2 + ep_is_in(EP))
>  
> +static inline struct ep_queue_head *get_qh_by_ep(struct fsl_ep *ep)
> +{
> +	/* we only have one ep0 structure but two queue heads */
> +	if (ep_index(ep) != 0)
> +		return ep->qh;
> +	else
> +		return &ep->udc->ep_qh[(ep->udc->ep0_dir ==
> +				USB_DIR_IN) ? 1 : 0];
> +}
> +
>  struct platform_device;
>  #ifdef CONFIG_ARCH_MXC
>  int fsl_udc_clk_init(struct platform_device *pdev);
> -- 
> 1.5.4.3
> 
Testing this patch at i.MX51 BBG, and it is OK.

Acked-by: Peter Chen <[email-masked]>
-- 

Best Regards,
Peter Chen