USB: EHCI: defer reclamation of siTDs

This patch (as1369) fixes a problem in ehci-hcd.  Some controllers
occasionally run into trouble when the driver reclaims siTDs too
quickly.  This can happen while streaming audio; it causes the
controller to crash.

The patch changes siTD reclamation to work the same way as iTD
reclamation: Completed siTDs are stored on a list and not reused until
at least one frame has passed.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Nate Case <ncase@xes-inc.com>
CC: <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 31 insertions, 9 deletions

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index a0aaaaff2560..805ec633a652 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -510,7 +510,7 @@ static int disable_periodic (struct ehci_hcd *ehci)
         ehci_writel(ehci, cmd, &ehci->regs->command);
         /* posted write ... */
 
-        free_cached_itd_list(ehci);
+        free_cached_lists(ehci);
 
         ehci->next_uframe = -1;
         return 0;
@@ -2139,13 +2139,27 @@ sitd_complete (
                         (stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
         }
         iso_stream_put (ehci, stream);
-        /* OK to recycle this SITD now that its completion callback ran. */
+
 done:
         sitd->urb = NULL;
-        sitd->stream = NULL;
-        list_move(&sitd->sitd_list, &stream->free_list);
-        iso_stream_put(ehci, stream);
-
+        if (ehci->clock_frame != sitd->frame) {
+                /* OK to recycle this SITD now. */
+                sitd->stream = NULL;
+                list_move(&sitd->sitd_list, &stream->free_list);
+                iso_stream_put(ehci, stream);
+        } else {
+                /* HW might remember this SITD, so we can't recycle it yet.
+                 * Move it to a safe place until a new frame starts.
+                 */
+                list_move(&sitd->sitd_list, &ehci->cached_sitd_list);
+                if (stream->refcount == 2) {
+                        /* If iso_stream_put() were called here, stream
+                         * would be freed.  Instead, just prevent reuse.
+                         */
+                        stream->ep->hcpriv = NULL;
+                        stream->ep = NULL;
+                }
+        }
         return retval;
 }
 
@@ -2211,9 +2225,10 @@ done:
 
 /*-------------------------------------------------------------------------*/
 
-static void free_cached_itd_list(struct ehci_hcd *ehci)
+static void free_cached_lists(struct ehci_hcd *ehci)
 {
         struct ehci_itd *itd, *n;
+        struct ehci_sitd *sitd, *sn;
 
         list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
                 struct ehci_iso_stream  *stream = itd->stream;
@@ -2221,6 +2236,13 @@ static void free_cached_itd_list(struct ehci_hcd *ehci)
                 list_move(&itd->itd_list, &stream->free_list);
                 iso_stream_put(ehci, stream);
         }
+
+        list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
+                struct ehci_iso_stream  *stream = sitd->stream;
+                sitd->stream = NULL;
+                list_move(&sitd->sitd_list, &stream->free_list);
+                iso_stream_put(ehci, stream);
+        }
 }
 
 /*-------------------------------------------------------------------------*/
@@ -2247,7 +2269,7 @@ scan_periodic (struct ehci_hcd *ehci)
                 clock_frame = -1;
         }
         if (ehci->clock_frame != clock_frame) {
-                free_cached_itd_list(ehci);
+                free_cached_lists(ehci);
                 ehci->clock_frame = clock_frame;
         }
         clock %= mod;
@@ -2414,7 +2436,7 @@ restart:
                         clock = now;
                         clock_frame = clock >> 3;
                         if (ehci->clock_frame != clock_frame) {
-                                free_cached_itd_list(ehci);
+                                free_cached_lists(ehci);
                                 ehci->clock_frame = clock_frame;
                         }
                 } else {