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

From: Peter Chen <[email-masked]>
Date: Tue, 22 Nov 2011 17:34:39 +0800

On Fri, Nov 11, 2011 at 08:38:13PM +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]>
> ---
>  drivers/usb/gadget/fsl_udc_core.c |   62 +++++++++++++++++-------------------
>  1 files changed, 29 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/usb/gadget/fsl_udc_core.c b/drivers/usb/gadget/fsl_udc_core.c
> index b2c44e1..beef9b7 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 = ep->qh;
It seems to can't get the correct qh pointer, you may still need to
use below code to get it
 	int i = ep_index(ep) * 2 + ep_is_in(ep);
 	struct ep_queue_head *dQH = &ep->udc->ep_qh[i];
> +
> +	/* 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);

After fixing above error, others are ok. I have tested it at i.mx51 bbg board
using 3.2.0-rc2+.
> -- 
> 1.5.4.3
> 
> 
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-- 

Best Regards,
Peter Chen