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Commit 5b484989 authored by Andreas Larsson's avatar Andreas Larsson Committed by Felipe Balbi
Browse files

usb: gadget: gr_udc: Add bounce buffer to handle odd sized OUT requests 



This adds a bounce buffer that handles the end of OUT requests where
req.length is not divisible by ep->ep.maxpacket.

Before this, such requests were rejected as the DMA engine cannot
restrict itself to buffers that are smaller than ep->ep.maxpacket.

Signed-off-by: default avatarAndreas Larsson <andreas@gaisler.com>
Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
parent af54954a

drivers/usb/gadget/udc/gr_udc.c

+60 −21
Original line number Diff line number Diff line
@@ -318,8 +318,26 @@ static void gr_finish_request(struct gr_ep *ep, struct gr_request *req, 
	usb_gadget_unmap_request(&dev->gadget, &req->req, ep->is_in);

	gr_free_dma_desc_chain(dev, req);



	if (ep->is_in) /* For OUT, actual gets updated bit by bit */

	if (ep->is_in) { /* For OUT, req->req.actual gets updated bit by bit */

		req->req.actual = req->req.length;

	} else if (req->oddlen && req->req.actual > req->evenlen) {

		/*

		 * Copy to user buffer in this case where length was not evenly

		 * divisible by ep->ep.maxpacket and the last descriptor was

		 * actually used.

		 */

		char *buftail = ((char *)req->req.buf + req->evenlen);



		memcpy(buftail, ep->tailbuf, req->oddlen);



		if (req->req.actual > req->req.length) {

			/* We got more data than was requested */

			dev_dbg(ep->dev->dev, "Overflow for ep %s\n",

				ep->ep.name);

			gr_dbgprint_request("OVFL", ep, req);

			req->req.status = -EOVERFLOW;

		}

	}



	if (!status) {

		if (ep->is_in)
@@ -379,6 +397,15 @@ static void gr_start_dma(struct gr_ep *ep) 
	/* A descriptor should already have been allocated */

	BUG_ON(!req->curr_desc);



	/*

	 * The DMA controller can not handle smaller OUT buffers than

	 * ep->ep.maxpacket. It could lead to buffer overruns if an unexpectedly

	 * long packet are received. Therefore an internal bounce buffer gets

	 * used when such a request gets enabled.

	 */

	if (!ep->is_in && req->oddlen)

		req->last_desc->data = ep->tailbuf_paddr;



	wmb(); /* Make sure all is settled before handing it over to DMA */



	/* Set the descriptor pointer in the hardware */
@@ -480,11 +507,11 @@ static int gr_setup_out_desc_list(struct gr_ep *ep, struct gr_request *req, 
		dma_addr_t start = req->req.dma + bytes_used;

		u16 size = min(bytes_left, ep->bytes_per_buffer);



		/* Should not happen however - gr_queue stops such lengths */

		if (size < ep->bytes_per_buffer)

			dev_warn(ep->dev->dev,

				 "Buffer overrun risk: %u < %u bytes/buffer\n",

				 size, ep->bytes_per_buffer);

		if (size < ep->bytes_per_buffer) {

			/* Prepare using bounce buffer */

			req->evenlen = req->req.length - bytes_left;

			req->oddlen = size;

		}



		ret = gr_add_dma_desc(ep, req, start, size, gfp_flags);

		if (ret)
@@ -584,18 +611,6 @@ static int gr_queue(struct gr_ep *ep, struct gr_request *req, gfp_t gfp_flags) 
		return -EINVAL;

	}



	/*

	 * The DMA controller can not handle smaller OUT buffers than

	 * maxpacket. It could lead to buffer overruns if unexpectedly long

	 * packet are received.

	 */

	if (!ep->is_in && (req->req.length % ep->ep.maxpacket) != 0) {

		dev_err(dev->dev,

			"OUT request length %d is not multiple of maxpacket\n",

			req->req.length);

		return -EMSGSIZE;

	}



	if (unlikely(!dev->driver || dev->gadget.speed == USB_SPEED_UNKNOWN)) {

		dev_err(dev->dev, "-ESHUTDOWN");

		return -ESHUTDOWN;
@@ -1286,8 +1301,8 @@ static int gr_handle_out_ep(struct gr_ep *ep) 
	if (ctrl & GR_DESC_OUT_CTRL_SE)

		req->setup = 1;



	if (len < ep->ep.maxpacket || req->req.actual == req->req.length) {

		/* Short packet or the expected size - we are done */

	if (len < ep->ep.maxpacket || req->req.actual >= req->req.length) {

		/* Short packet or >= expected size - we are done */



		if ((ep == &dev->epo[0]) && (dev->ep0state == GR_EP0_OSTATUS)) {

			/*
@@ -2015,6 +2030,11 @@ static int gr_ep_init(struct gr_udc *dev, int num, int is_in, u32 maxplimit) 
	}

	list_add_tail(&ep->ep_list, &dev->ep_list);



	ep->tailbuf = dma_alloc_coherent(dev->dev, ep->ep.maxpacket_limit,

					 &ep->tailbuf_paddr, GFP_ATOMIC);

	if (!ep->tailbuf)

		return -ENOMEM;



	return 0;

}
@@ -2067,9 +2087,24 @@ static int gr_udc_init(struct gr_udc *dev) 
	return 0;

}



static void gr_ep_remove(struct gr_udc *dev, int num, int is_in)

{

	struct gr_ep *ep;



	if (is_in)

		ep = &dev->epi[num];

	else

		ep = &dev->epo[num];



	if (ep->tailbuf)

		dma_free_coherent(dev->dev, ep->ep.maxpacket_limit,

				  ep->tailbuf, ep->tailbuf_paddr);

}



static int gr_remove(struct platform_device *pdev)

{

	struct gr_udc *dev = platform_get_drvdata(pdev);

	int i;



	if (dev->added)

		usb_del_gadget_udc(&dev->gadget); /* Shuts everything down */
@@ -2084,6 +2119,11 @@ static int gr_remove(struct platform_device *pdev) 
	gr_free_request(&dev->epi[0].ep, &dev->ep0reqi->req);

	gr_free_request(&dev->epo[0].ep, &dev->ep0reqo->req);



	for (i = 0; i < dev->nepo; i++)

		gr_ep_remove(dev, i, 0);

	for (i = 0; i < dev->nepi; i++)

		gr_ep_remove(dev, i, 1);



	return 0;

}

static int gr_request_irq(struct gr_udc *dev, int irq)
@@ -2131,7 +2171,6 @@ static int gr_probe(struct platform_device *pdev) 
	dev->gadget.name = driver_name;

	dev->gadget.max_speed = USB_SPEED_HIGH;

	dev->gadget.ops = &gr_ops;

	dev->gadget.quirk_ep_out_aligned_size = true;



	spin_lock_init(&dev->lock);

	dev->regs = regs;

drivers/usb/gadget/udc/gr_udc.h

+7 −0
Original line number Diff line number Diff line
@@ -156,6 +156,10 @@ struct gr_ep { 
	struct list_head queue;



	struct list_head ep_list;



	/* Bounce buffer for end of "odd" sized OUT requests */

	void *tailbuf;

	dma_addr_t tailbuf_paddr;

};



struct gr_request {
@@ -167,6 +171,9 @@ struct gr_request { 
	struct gr_dma_desc *curr_desc; /* Current descriptor */

	struct gr_dma_desc *last_desc; /* Last in the chain */



	u16 evenlen; /* Size of even length head (if oddlen != 0) */

	u16 oddlen; /* Size of odd length tail if buffer length is "odd" */



	u8 setup; /* Setup packet */

};