libpayload: Add interrupt-queue underrun recovery to EHCI
If the queue of an interrupt transfer runs out, we have to reset
the queue head. This also introduces the use of a spare transfer
descriptor (TD) in interrupt queues, which assures, that a processed
TD won't be reused until the host controller has written it back
from his overlay.
Change-Id: Id0eeb2808b77f1c187f164eb34bd66f8f399938b
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/1123
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins)
diff --git a/payloads/libpayload/drivers/usb/ehci.c b/payloads/libpayload/drivers/usb/ehci.c
index 27e160b..aaadf2d 100644
--- a/payloads/libpayload/drivers/usb/ehci.c
+++ b/payloads/libpayload/drivers/usb/ehci.c
@@ -410,6 +410,7 @@
volatile ehci_qh_t qh;
intr_qtd_t *head;
intr_qtd_t *tail;
+ intr_qtd_t *spare;
u8 *data;
endpoint_t *endp;
int reqsize;
@@ -466,7 +467,11 @@
intr_queue_t *const intrq =
(intr_queue_t *)memalign(32, sizeof(intr_queue_t));
- u8 *data = (u8 *)malloc(reqsize * reqcount);
+ /*
+ * reqcount data chunks
+ * plus one more spare, which we'll leave out of queue
+ */
+ u8 *data = (u8 *)malloc(reqsize * (reqcount + 1));
if (!intrq || !data)
fatal("Not enough memory to create USB interrupt queue.\n");
intrq->data = data;
@@ -490,6 +495,10 @@
}
intrq->tail = cur_td;
+ /* create spare qTD */
+ intrq->spare = (intr_qtd_t *)memalign(32, sizeof(intr_qtd_t));
+ fill_intr_queue_td(intrq, intrq->spare, data);
+
/* initialize QH */
const int endp = ep->endpoint & 0xf;
memset(&intrq->qh, 0, sizeof(intrq->qh));
@@ -558,6 +567,7 @@
/* free current interrupt qTD */
free(to_free);
}
+ free(intrq->spare);
free(intrq->data);
free(intrq);
}
@@ -569,9 +579,7 @@
u8 *ret = NULL;
/* process if head qTD is inactive AND QH has been moved forward */
- if (!(intrq->head->td.token & QTD_ACTIVE) &&
- (intrq->qh.current_td_ptr !=
- virt_to_phys(&intrq->head->td))) {
+ if (!(intrq->head->td.token & QTD_ACTIVE)) {
if (!(intrq->head->td.token & QTD_STATUS_MASK))
ret = intrq->head->data;
else
@@ -579,18 +587,21 @@
"status == 0x%02x\n",
intrq->head->td.token & QTD_STATUS_MASK);
- /* save and advance our head ptr */
- intr_qtd_t *const new_td = intrq->head;
- intrq->head = intrq->head->next;
-
- /* reuse executed qTD */
- fill_intr_queue_td(intrq, new_td, new_td->data);
-
- /* at last insert reused qTD at the
- * end and advance our tail ptr */
- intrq->tail->td.next_qtd = virt_to_phys(&new_td->td);
- intrq->tail->next = new_td;
+ /* insert spare qTD at the end and advance our tail ptr */
+ fill_intr_queue_td(intrq, intrq->spare, intrq->spare->data);
+ intrq->tail->td.next_qtd = virt_to_phys(&intrq->spare->td);
+ intrq->tail->next = intrq->spare;
intrq->tail = intrq->tail->next;
+
+ /* reuse executed qTD as spare one and advance our head ptr */
+ intrq->spare = intrq->head;
+ intrq->head = intrq->head->next;
+ }
+ /* reset queue if we fully processed it after underrun */
+ else if (intrq->qh.td.next_qtd & QTD_TERMINATE) {
+ debug("resetting underrun ehci interrupt queue.\n");
+ memset(&intrq->qh.td, 0, sizeof(intrq->qh.td));
+ intrq->qh.td.next_qtd = virt_to_phys(&intrq->head->td);
}
return ret;
}