From: Andiry Xu <andiry.xu@xxxxxxx>
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: Andiry Xu <andiry.xu@xxxxxxx>
Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
Tested-by: Paul Zimmerman <Paul.Zimmerman@xxxxxxxxxxxx>
---
drivers/usb/host/xhci-mem.c | 6 ++
drivers/usb/host/xhci-ring.c | 105 +++++++++++++++++++++++-------------------
drivers/usb/host/xhci.c | 1 +
drivers/usb/host/xhci.h | 2 +
4 files changed, 67 insertions(+), 47 deletions(-)
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index bdea4de..212012c 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -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;
}
/**
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index ad68a28..f9b6fa3 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -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;
+
+ return 0;
}
/* 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);
}
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 262400c..dec5b2d 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -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.
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 2337a8e..ea8fc23 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -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;
};
--
1.7.9
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