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Commit b008df60 authored by Andiry Xu's avatar Andiry Xu Committed by Sarah Sharp
Browse files

xHCI: count free TRBs on transfer ring 



In the past, the room_on_ring() check was implemented by walking all over
the ring, which is wasteful and complicated.

Count the number of free TRBs instead. The free TRBs number should be
updated when enqueue/dequeue pointer is updated, or upon the completion
of a set dequeue pointer command.

Signed-off-by: default avatarAndiry Xu <andiry.xu@amd.com>
Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
Tested-by: default avatarPaul Zimmerman <Paul.Zimmerman@synopsys.com>
parent 3fe4fe08

drivers/usb/host/xhci-mem.c

+6 −0
Original line number Diff line number Diff line
@@ -135,6 +135,12 @@ static void xhci_initialize_ring_info(struct xhci_ring *ring) 
	/* Not necessary for new rings, but needed for re-initialized rings */

	ring->enq_updates = 0;

	ring->deq_updates = 0;



	/*

	 * Each segment has a link TRB, and leave an extra TRB for SW

	 * accounting purpose

	 */

	ring->num_trbs_free = ring->num_segs * (TRBS_PER_SEGMENT - 1) - 1;

}



/**

drivers/usb/host/xhci-ring.c

+58 −47
Original line number Diff line number Diff line
@@ -145,10 +145,17 @@ static void next_trb(struct xhci_hcd *xhci, 
 */

static void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring)

{

	union xhci_trb *next = ++(ring->dequeue);

	union xhci_trb *next;

	unsigned long long addr;



	ring->deq_updates++;



	/* If this is not event ring, there is one more usable TRB */

	if (ring->type != TYPE_EVENT &&

			!last_trb(xhci, ring, ring->deq_seg, ring->dequeue))

		ring->num_trbs_free++;

	next = ++(ring->dequeue);



	/* Update the dequeue pointer further if that was a link TRB or we're at

	 * the end of an event ring segment (which doesn't have link TRBS)

	 */
@@ -189,6 +196,10 @@ static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring, 
	unsigned long long addr;



	chain = le32_to_cpu(ring->enqueue->generic.field[3]) & TRB_CHAIN;

	/* If this is not event ring, there is one less usable TRB */

	if (ring->type != TYPE_EVENT &&

			!last_trb(xhci, ring, ring->enq_seg, ring->enqueue))

		ring->num_trbs_free--;

	next = ++(ring->enqueue);



	ring->enq_updates++;
@@ -240,54 +251,14 @@ static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring, 
/*

 * Check to see if there's room to enqueue num_trbs on the ring.  See rules

 * above.

 * FIXME: this would be simpler and faster if we just kept track of the number

 * of free TRBs in a ring.

 */

static int room_on_ring(struct xhci_hcd *xhci, struct xhci_ring *ring,

static inline int room_on_ring(struct xhci_hcd *xhci, struct xhci_ring *ring,

		unsigned int num_trbs)

{

	int i;

	union xhci_trb *enq = ring->enqueue;

	struct xhci_segment *enq_seg = ring->enq_seg;

	struct xhci_segment *cur_seg;

	unsigned int left_on_ring;



	/* If we are currently pointing to a link TRB, advance the

	 * enqueue pointer before checking for space */

	while (last_trb(xhci, ring, enq_seg, enq)) {

		enq_seg = enq_seg->next;

		enq = enq_seg->trbs;

	}



	/* Check if ring is empty */

	if (enq == ring->dequeue) {

		/* Can't use link trbs */

		left_on_ring = TRBS_PER_SEGMENT - 1;

		for (cur_seg = enq_seg->next; cur_seg != enq_seg;

				cur_seg = cur_seg->next)

			left_on_ring += TRBS_PER_SEGMENT - 1;



		/* Always need one TRB free in the ring. */

		left_on_ring -= 1;

		if (num_trbs > left_on_ring) {

			xhci_warn(xhci, "Not enough room on ring; "

					"need %u TRBs, %u TRBs left\n",

					num_trbs, left_on_ring);

			return 0;

		}

	if (ring->num_trbs_free >= num_trbs)

		return 1;

	}

	/* Make sure there's an extra empty TRB available */

	for (i = 0; i <= num_trbs; ++i) {

		if (enq == ring->dequeue)



	return 0;

		enq++;

		while (last_trb(xhci, ring, enq_seg, enq)) {

			enq_seg = enq_seg->next;

			enq = enq_seg->trbs;

		}

	}

	return 1;

}



/* Ring the host controller doorbell after placing a command on the ring */
@@ -893,6 +864,43 @@ void xhci_stop_endpoint_command_watchdog(unsigned long arg) 
	xhci_dbg(xhci, "xHCI host controller is dead.\n");

}





static void update_ring_for_set_deq_completion(struct xhci_hcd *xhci,

		struct xhci_virt_device *dev,

		struct xhci_ring *ep_ring,

		unsigned int ep_index)

{

	union xhci_trb *dequeue_temp;

	int num_trbs_free_temp;

	bool revert = false;



	num_trbs_free_temp = ep_ring->num_trbs_free;

	dequeue_temp = ep_ring->dequeue;



	while (ep_ring->dequeue != dev->eps[ep_index].queued_deq_ptr) {

		/* We have more usable TRBs */

		ep_ring->num_trbs_free++;

		ep_ring->dequeue++;

		if (last_trb(xhci, ep_ring, ep_ring->deq_seg,

				ep_ring->dequeue)) {

			if (ep_ring->dequeue ==

					dev->eps[ep_index].queued_deq_ptr)

				break;

			ep_ring->deq_seg = ep_ring->deq_seg->next;

			ep_ring->dequeue = ep_ring->deq_seg->trbs;

		}

		if (ep_ring->dequeue == dequeue_temp) {

			revert = true;

			break;

		}

	}



	if (revert) {

		xhci_dbg(xhci, "Unable to find new dequeue pointer\n");

		ep_ring->num_trbs_free = num_trbs_free_temp;

	}

}



/*

 * When we get a completion for a Set Transfer Ring Dequeue Pointer command,

 * we need to clear the set deq pending flag in the endpoint ring state, so that
@@ -974,8 +982,8 @@ static void handle_set_deq_completion(struct xhci_hcd *xhci, 
			/* Update the ring's dequeue segment and dequeue pointer

			 * to reflect the new position.

			 */

			ep_ring->deq_seg = dev->eps[ep_index].queued_deq_seg;

			ep_ring->dequeue = dev->eps[ep_index].queued_deq_ptr;

			update_ring_for_set_deq_completion(xhci, dev,

				ep_ring, ep_index);

		} else {

			xhci_warn(xhci, "Mismatch between completed Set TR Deq "

					"Ptr command & xHCI internal state.\n");
@@ -3407,6 +3415,7 @@ cleanup: 
	ep_ring->enqueue = urb_priv->td[0]->first_trb;

	ep_ring->enq_seg = urb_priv->td[0]->start_seg;

	ep_ring->cycle_state = start_cycle;

	ep_ring->num_trbs_free = ep_ring->num_trbs_free_temp;

	usb_hcd_unlink_urb_from_ep(bus_to_hcd(urb->dev->bus), urb);

	return ret;

}
@@ -3479,6 +3488,8 @@ int xhci_queue_isoc_tx_prepare(struct xhci_hcd *xhci, gfp_t mem_flags, 
				urb->dev->speed == USB_SPEED_FULL)

			urb->interval /= 8;

	}

	ep_ring->num_trbs_free_temp = ep_ring->num_trbs_free;



	return xhci_queue_isoc_tx(xhci, GFP_ATOMIC, urb, slot_id, ep_index);

}

drivers/usb/host/xhci.c

+1 −0
Original line number Diff line number Diff line
@@ -729,6 +729,7 @@ static void xhci_clear_command_ring(struct xhci_hcd *xhci) 
	ring->enq_seg = ring->deq_seg;

	ring->enqueue = ring->dequeue;



	ring->num_trbs_free = ring->num_segs * (TRBS_PER_SEGMENT - 1) - 1;

	/*

	 * Ring is now zeroed, so the HW should look for change of ownership

	 * when the cycle bit is set to 1.

drivers/usb/host/xhci.h

+2 −0
Original line number Diff line number Diff line
@@ -1278,6 +1278,8 @@ struct xhci_ring { 
	u32			cycle_state;

	unsigned int		stream_id;

	unsigned int		num_segs;

	unsigned int		num_trbs_free;

	unsigned int		num_trbs_free_temp;

	enum xhci_ring_type	type;

	bool			last_td_was_short;

};