usb: xhci: Add support for URB_ZERO_PACKET to bulk/sg transfers

This commit checks for the URB_ZERO_PACKET flag and creates an extra
zero-length td if the urb transfer length is a multiple of the endpoint's
max packet length.

Signed-off-by: Reyad Attiyat <reyad.attiyat@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -3041,9 +3041,11 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 	struct xhci_td *td;
 	struct scatterlist *sg;
 	int num_sgs;
-	int trb_buff_len, this_sg_len, running_total;
+	int trb_buff_len, this_sg_len, running_total, ret;
 	unsigned int total_packet_count;
+	bool zero_length_needed;
 	bool first_trb;
+	int last_trb_num;
 	u64 addr;
 	bool more_trbs_coming;
 
@@ -3059,13 +3061,27 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 	total_packet_count = DIV_ROUND_UP(urb->transfer_buffer_length,
 			usb_endpoint_maxp(&urb->ep->desc));
 
-	trb_buff_len = prepare_transfer(xhci, xhci->devs[slot_id],
+	ret = prepare_transfer(xhci, xhci->devs[slot_id],
 			ep_index, urb->stream_id,
 			num_trbs, urb, 0, mem_flags);
-	if (trb_buff_len < 0)
+	if (ret < 0)
-		return trb_buff_len;
+		return ret;
 
 	urb_priv = urb->hcpriv;
+
+	/* Deal with URB_ZERO_PACKET - need one more td/trb */
+	zero_length_needed = urb->transfer_flags & URB_ZERO_PACKET &&
+		urb_priv->length == 2;
+	if (zero_length_needed) {
+		num_trbs++;
+		xhci_dbg(xhci, "Creating zero length td.\n");
+		ret = prepare_transfer(xhci, xhci->devs[slot_id],
+				ep_index, urb->stream_id,
+				1, urb, 1, mem_flags);
+		if (ret < 0)
+			return ret;
+	}
+
 	td = urb_priv->td[0];
 
 	/*
@@ -3095,6 +3111,7 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		trb_buff_len = urb->transfer_buffer_length;
 
 	first_trb = true;
+	last_trb_num = zero_length_needed ? 2 : 1;
 	/* Queue the first TRB, even if it's zero-length */
 	do {
 		u32 field = 0;
@@ -3112,12 +3129,15 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		/* Chain all the TRBs together; clear the chain bit in the last
 		 * TRB to indicate it's the last TRB in the chain.
 		 */
-		if (num_trbs > 1) {
+		if (num_trbs > last_trb_num) {
 			field |= TRB_CHAIN;
-		} else {
+		} else if (num_trbs == last_trb_num) {
-			/* FIXME - add check for ZERO_PACKET flag before this */
 			td->last_trb = ep_ring->enqueue;
 			field |= TRB_IOC;
+		} else if (zero_length_needed && num_trbs == 1) {
+			trb_buff_len = 0;
+			urb_priv->td[1]->last_trb = ep_ring->enqueue;
+			field |= TRB_IOC;
 		}
 
 		/* Only set interrupt on short packet for IN endpoints */
@@ -3179,7 +3199,7 @@ static int queue_bulk_sg_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		if (running_total + trb_buff_len > urb->transfer_buffer_length)
 			trb_buff_len =
 				urb->transfer_buffer_length - running_total;
-	} while (running_total < urb->transfer_buffer_length);
+	} while (num_trbs > 0);
 
 	check_trb_math(urb, num_trbs, running_total);
 	giveback_first_trb(xhci, slot_id, ep_index, urb->stream_id,
@@ -3197,7 +3217,9 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 	int num_trbs;
 	struct xhci_generic_trb *start_trb;
 	bool first_trb;
+	int last_trb_num;
 	bool more_trbs_coming;
+	bool zero_length_needed;
 	int start_cycle;
 	u32 field, length_field;
 
@@ -3228,7 +3250,6 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		num_trbs++;
 		running_total += TRB_MAX_BUFF_SIZE;
 	}
-	/* FIXME: this doesn't deal with URB_ZERO_PACKET - need one more */
 
 	ret = prepare_transfer(xhci, xhci->devs[slot_id],
 			ep_index, urb->stream_id,
@@ -3237,6 +3258,20 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		return ret;
 
 	urb_priv = urb->hcpriv;
+
+	/* Deal with URB_ZERO_PACKET - need one more td/trb */
+	zero_length_needed = urb->transfer_flags & URB_ZERO_PACKET &&
+		urb_priv->length == 2;
+	if (zero_length_needed) {
+		num_trbs++;
+		xhci_dbg(xhci, "Creating zero length td.\n");
+		ret = prepare_transfer(xhci, xhci->devs[slot_id],
+				ep_index, urb->stream_id,
+				1, urb, 1, mem_flags);
+		if (ret < 0)
+			return ret;
+	}
+
 	td = urb_priv->td[0];
 
 	/*
@@ -3258,7 +3293,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		trb_buff_len = urb->transfer_buffer_length;
 
 	first_trb = true;
-
+	last_trb_num = zero_length_needed ? 2 : 1;
 	/* Queue the first TRB, even if it's zero-length */
 	do {
 		u32 remainder = 0;
@@ -3275,12 +3310,15 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		/* Chain all the TRBs together; clear the chain bit in the last
 		 * TRB to indicate it's the last TRB in the chain.
 		 */
-		if (num_trbs > 1) {
+		if (num_trbs > last_trb_num) {
 			field |= TRB_CHAIN;
-		} else {
+		} else if (num_trbs == last_trb_num) {
-			/* FIXME - add check for ZERO_PACKET flag before this */
 			td->last_trb = ep_ring->enqueue;
 			field |= TRB_IOC;
+		} else if (zero_length_needed && num_trbs == 1) {
+			trb_buff_len = 0;
+			urb_priv->td[1]->last_trb = ep_ring->enqueue;
+			field |= TRB_IOC;
 		}
 
 		/* Only set interrupt on short packet for IN endpoints */
@@ -3318,7 +3356,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		trb_buff_len = urb->transfer_buffer_length - running_total;
 		if (trb_buff_len > TRB_MAX_BUFF_SIZE)
 			trb_buff_len = TRB_MAX_BUFF_SIZE;
-	} while (running_total < urb->transfer_buffer_length);
+	} while (num_trbs > 0);
 
 	check_trb_math(urb, num_trbs, running_total);
 	giveback_first_trb(xhci, slot_id, ep_index, urb->stream_id,

drivers/usb/host/xhci.c

@@ -1340,6 +1340,11 @@ int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
 
 	if (usb_endpoint_xfer_isoc(&urb->ep->desc))
 		size = urb->number_of_packets;
+	else if (usb_endpoint_is_bulk_out(&urb->ep->desc) &&
+	    urb->transfer_buffer_length > 0 &&
+	    urb->transfer_flags & URB_ZERO_PACKET &&
+	    !(urb->transfer_buffer_length % usb_endpoint_maxp(&urb->ep->desc)))
+		size = 2;
 	else
 		size = 1;