These patches are against kernels 2.6.18 through at least 2.6.18-git7.
patch 8: split frame scanning code out of the scan_periodic schedule
walking loop so that the same code can be used to scan preceeding
frame for completions when FSTN and sITD frame spanning support are
added. Add restrictions on the timing of processing QH and sITD
completions in the current frame to avoid a race where a current
frame's completion may inadvertantly be processed before a preceeding
frame's spanning completion (do not process current completions until
preceeding transactions were checked for completion at a time that
guarantees they'd have finished).
Signed-off-by: Christopher "Monty" Montgomery <[EMAIL PROTECTED]>
---
diff -X b/Documentation/dontdiff -upr a/drivers/usb/host/ehci-sched.c
b/drivers/usb/host/ehci-sched.c
--- a/drivers/usb/host/ehci-sched.c 2006-09-26 22:26:57.000000000 -0400
+++ b/drivers/usb/host/ehci-sched.c 2006-09-26 22:27:05.000000000 -0400
@@ -2277,6 +2277,152 @@ done:
return status;
}
+/*-------------------------------------------------------------------------*/
+
+static int scan_frame(struct ehci_hcd *ehci, struct pt_regs *regs,
+ int frame, int uframes, int rescan){
+
+ unsigned modified = 0;
+ union ehci_shadow q, *q_p;
+ __le32 type, *hw_p;
+
+ frame = frame & (ehci->periodic_size-1);
+
+ q_p = &ehci->pshadow [frame];
+ hw_p = &ehci->periodic [frame];
+
+ q.ptr = q_p->ptr;
+ type = Q_NEXT_TYPE (*hw_p);
+
+ while (q.ptr != NULL) {
+ unsigned uf;
+ union ehci_shadow temp;
+ int live;
+
+ live = HC_IS_RUNNING (ehci_to_hcd(ehci)->state);
+ switch (type) {
+ case Q_TYPE_QH:
+ /* handle any completions */
+ temp.qh = qh_get (q.qh);
+ q_p = &q.qh->qh_next;
+ hw_p = &q.qh->hw_next;
+ type = Q_NEXT_TYPE (*hw_p);
+
+ q = *q_p;
+
+ modified = qh_completions (ehci, temp.qh, regs);
+ if (unlikely (list_empty (&temp.qh->qtd_list)))
+ periodic_qh_deschedule (ehci, temp.qh);
+
+ qh_put (temp.qh);
+ break;
+ case Q_TYPE_FSTN:
+
+ /* for save-place FSTNs, inspect all QH
+ * entries in the previous frame for
+ * completions, but not if we're already in
+ * recovery mode. */
+
+ if (q.fstn->hw_prev != EHCI_LIST_END && !rescan) {
+ modified = scan_frame (ehci,regs,frame-1,8,1);
+ rescan = 1;
+ }
+
+ q_p = &q.fstn->fstn_next;
+ hw_p = &q.fstn->hw_next;
+ type = Q_NEXT_TYPE (*hw_p);
+ q = *q_p;
+
+ break;
+
+ case Q_TYPE_ITD:
+ /* skip itds for later in the frame */
+ rmb ();
+ for (uf = live ? uframes : 8; uf < 8; uf++) {
+ if (0 == (q.itd->hw_transaction [uf]
+ & ITD_ACTIVE))
+ continue;
+ q_p = &q.itd->itd_next;
+ hw_p = &q.itd->hw_next;
+ type = Q_NEXT_TYPE (*hw_p);
+ q = *q_p;
+ break;
+ }
+ if (uf != 8)
+ break;
+
+ /* this one's ready ... HC won't cache the
+ * pointer for much longer, if at all.
+ */
+ *q_p = q.itd->itd_next;
+ *hw_p = q.itd->hw_next;
+ type = Q_NEXT_TYPE (*hw_p);
+ wmb();
+ modified = itd_complete (ehci, q.itd, regs);
+ q = *q_p;
+ break;
+
+ case Q_TYPE_SITD:
+
+ /* is this a spanning dummy? */
+ if (q.sitd->hw_backpointer != EHCI_LIST_END){
+ q_p = &q.sitd->sitd_next;
+ hw_p = &q.sitd->hw_next;
+ type = Q_NEXT_TYPE (*hw_p);
+ q = *q_p;
+
+ if(rescan) break;
+
+ /* note that the original sITD's
+ completion will unlink the dummy */
+ modified = scan_frame(ehci,regs,
+ frame-1,8,1);
+ rescan = 1;
+
+ }else{
+ /* process completions for this frame only if
+ * we're certain all completions for a
+ * preceeding spanning frame have first been
+ * processed; that is true iff clock was past
+ * uframe 1 when we started */
+ if ( ((q.sitd->hw_results & SITD_ACTIVE) ||
+ uframes < 3)
+ && live) {
+ q_p = &q.sitd->sitd_next;
+ hw_p = &q.sitd->hw_next;
+ type = Q_NEXT_TYPE (*hw_p);
+ q = *q_p;
+ break;
+ }
+
+ /* unlink the sITD */
+ *q_p = q.sitd->sitd_next;
+ *hw_p = q.sitd->hw_next;
+ type = Q_NEXT_TYPE (*hw_p);
+ wmb();
+
+ /* when spanning sITD support is
+ * added, the spanning dummy will be
+ * unlinked here as well. */
+
+ modified = sitd_complete (ehci, q.sitd, regs);
+
+ q = *q_p;
+ }
+ break;
+ default:
+ dbg ("corrupt type %d frame %d shadow %p",
+ type, frame, q.ptr);
+ // BUG ();
+ q.ptr = NULL;
+ }
+
+ /* assume completion callbacks modify the queue */
+ if (unlikely (modified)) return 1;
+ }
+ return 0;
+}
+
/* scan_periodic - completion worker; called out of interrupt (or
* poll) handler to finish processing of transactions that have been
* completed by the host controller. Also now has the responsibility
@@ -2290,7 +2436,6 @@ static void
scan_periodic (struct ehci_hcd *ehci, struct pt_regs *regs)
{
unsigned frame, clock, now_uframe, mod;
- unsigned modified;
mod = ehci->periodic_size << 3;
@@ -2307,9 +2452,8 @@ scan_periodic (struct ehci_hcd *ehci, st
clock %= mod;
for (;;) {
- union ehci_shadow q, *q_p;
- __le32 type, *hw_p;
unsigned uframes;
+ int repeat = 1;
/* don't scan past the live uframe */
frame = now_uframe >> 3;
@@ -2321,94 +2465,10 @@ scan_periodic (struct ehci_hcd *ehci, st
uframes = 8;
}
-restart:
- /* scan each element in frame's queue for completions */
- q_p = &ehci->pshadow [frame];
- hw_p = &ehci->periodic [frame];
- q.ptr = q_p->ptr;
- type = Q_NEXT_TYPE (*hw_p);
- modified = 0;
-
- while (q.ptr != NULL) {
- unsigned uf;
- union ehci_shadow temp;
- int live;
-
- live = HC_IS_RUNNING (ehci_to_hcd(ehci)->state);
- switch (type) {
- case Q_TYPE_QH:
- /* handle any completions */
- temp.qh = qh_get (q.qh);
- type = Q_NEXT_TYPE (q.qh->hw_next);
- q = q.qh->qh_next;
- modified = qh_completions (ehci, temp.qh, regs);
- if (unlikely (list_empty (&temp.qh->qtd_list)))
- periodic_qh_deschedule (ehci, temp.qh);
- qh_put (temp.qh);
- break;
- case Q_TYPE_FSTN:
- /* for "save place" FSTNs, look at QH entries
- * in the previous frame for completions.
- */
- if (q.fstn->hw_prev != EHCI_LIST_END) {
- dbg ("ignoring completions from FSTNs");
- }
- type = Q_NEXT_TYPE (q.fstn->hw_next);
- q = q.fstn->fstn_next;
- break;
- case Q_TYPE_ITD:
- /* skip itds for later in the frame */
- rmb ();
- for (uf = live ? uframes : 8; uf < 8; uf++) {
- if (0 == (q.itd->hw_transaction [uf]
- & ITD_ACTIVE))
- continue;
- q_p = &q.itd->itd_next;
- hw_p = &q.itd->hw_next;
- type = Q_NEXT_TYPE (q.itd->hw_next);
- q = *q_p;
- break;
- }
- if (uf != 8)
- break;
-
- /* this one's ready ... HC won't cache the
- * pointer for much longer, if at all.
- */
- *q_p = q.itd->itd_next;
- *hw_p = q.itd->hw_next;
- type = Q_NEXT_TYPE (q.itd->hw_next);
- wmb();
- modified = itd_complete (ehci, q.itd, regs);
- q = *q_p;
- break;
- case Q_TYPE_SITD:
- if ((q.sitd->hw_results & SITD_ACTIVE)
- && live) {
- q_p = &q.sitd->sitd_next;
- hw_p = &q.sitd->hw_next;
- type = Q_NEXT_TYPE (q.sitd->hw_next);
- q = *q_p;
- break;
- }
- *q_p = q.sitd->sitd_next;
- *hw_p = q.sitd->hw_next;
- type = Q_NEXT_TYPE (q.sitd->hw_next);
- wmb();
- modified = sitd_complete (ehci, q.sitd, regs);
- q = *q_p;
- break;
- default:
- dbg ("corrupt type %d frame %d shadow %p",
- type, frame, q.ptr);
- // BUG ();
- q.ptr = NULL;
- }
-
- /* assume completion callbacks modify the queue */
- if (unlikely (modified))
- goto restart;
- }
+ /* scan each element in frame's queue for completions */
+ while(repeat)
+ repeat = scan_frame(ehci, regs, frame, uframes, 0);
+
/* stop when we catch up to the HC */
@@ -2425,6 +2485,7 @@ restart:
if (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
break;
+
ehci->next_uframe = now_uframe;
now = readl (&ehci->regs->frame_index) % mod;
if (now_uframe == now)
@@ -2437,7 +2498,7 @@ restart:
now_uframe %= mod;
if(now_uframe == 0){
-
+
/* if the periodic schedule is still marked
to be disabled after a complete pass,
disable it now */
-------------------------------------------------------------------------
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