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authorKarsten Wiese <fzu@wemgehoertderstaat.de>2009-02-09 03:07:58 +0300
committerGreg Kroah-Hartman <gregkh@suse.de>2009-02-28 01:40:50 +0300
commit9aa09d2f8f4bc440d6db1c3414d4009642875240 (patch)
tree11b8735a5ddb24fcb4b810b9af3959a8aae6a1ae
parent9a6e184c804b33a2c2ea974efcd3c9798d30cb39 (diff)
downloadlinux-9aa09d2f8f4bc440d6db1c3414d4009642875240.tar.xz
USB: EHCI: slow down ITD reuse
Currently ITDs are immediately recycled whenever their URB completes. However, EHCI hardware can sometimes remember some ITD state. This means that when the ITD is reused before end-of-frame it may sometimes cause the hardware to reference bogus state. This patch defers reusing such ITDs by moving them into a new ehci member cached_itd_list. ITDs resting in cached_itd_list are moved back into their stream's free_list once scan_periodic() detects that the active frame has elapsed. This makes the snd_usb_us122l driver (in kernel since .28) work right when it's hooked up through EHCI. [ dbrownell@users.sourceforge.net: comment fixups ] Signed-off-by: Karsten Wiese <fzu@wemgehoertderstaat.de> Tested-by: Philippe Carriere <philippe-f.carriere@wanadoo.fr> Tested-by: Federico Briata <federicobriata@gmail.com> Cc: stable <stable@kernel.org> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/usb/host/ehci-hcd.c2
-rw-r--r--drivers/usb/host/ehci-mem.c1
-rw-r--r--drivers/usb/host/ehci-sched.c56
-rw-r--r--drivers/usb/host/ehci.h6
4 files changed, 57 insertions, 8 deletions
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 4725d15d096f..e551bb38852b 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -485,6 +485,7 @@ static int ehci_init(struct usb_hcd *hcd)
* periodic_size can shrink by USBCMD update if hcc_params allows.
*/
ehci->periodic_size = DEFAULT_I_TDPS;
+ INIT_LIST_HEAD(&ehci->cached_itd_list);
if ((retval = ehci_mem_init(ehci, GFP_KERNEL)) < 0)
return retval;
@@ -497,6 +498,7 @@ static int ehci_init(struct usb_hcd *hcd)
ehci->reclaim = NULL;
ehci->next_uframe = -1;
+ ehci->clock_frame = -1;
/*
* dedicate a qh for the async ring head, since we couldn't unlink
diff --git a/drivers/usb/host/ehci-mem.c b/drivers/usb/host/ehci-mem.c
index 0431397836f6..10d52919abbb 100644
--- a/drivers/usb/host/ehci-mem.c
+++ b/drivers/usb/host/ehci-mem.c
@@ -128,6 +128,7 @@ static inline void qh_put (struct ehci_qh *qh)
static void ehci_mem_cleanup (struct ehci_hcd *ehci)
{
+ free_cached_itd_list(ehci);
if (ehci->async)
qh_put (ehci->async);
ehci->async = NULL;
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index a081ee65bde6..07bcb931021b 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1004,7 +1004,8 @@ iso_stream_put(struct ehci_hcd *ehci, struct ehci_iso_stream *stream)
is_in = (stream->bEndpointAddress & USB_DIR_IN) ? 0x10 : 0;
stream->bEndpointAddress &= 0x0f;
- stream->ep->hcpriv = NULL;
+ if (stream->ep)
+ stream->ep->hcpriv = NULL;
if (stream->rescheduled) {
ehci_info (ehci, "ep%d%s-iso rescheduled "
@@ -1653,14 +1654,28 @@ itd_complete (
(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
}
iso_stream_put (ehci, stream);
- /* OK to recycle this ITD now that its completion callback ran. */
+
done:
usb_put_urb(urb);
itd->urb = NULL;
- itd->stream = NULL;
- list_move(&itd->itd_list, &stream->free_list);
- iso_stream_put(ehci, stream);
-
+ if (ehci->clock_frame != itd->frame || itd->index[7] != -1) {
+ /* OK to recycle this ITD now. */
+ itd->stream = NULL;
+ list_move(&itd->itd_list, &stream->free_list);
+ iso_stream_put(ehci, stream);
+ } else {
+ /* HW might remember this ITD, so we can't recycle it yet.
+ * Move it to a safe place until a new frame starts.
+ */
+ list_move(&itd->itd_list, &ehci->cached_itd_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;
}
@@ -2101,6 +2116,20 @@ done:
/*-------------------------------------------------------------------------*/
+static void free_cached_itd_list(struct ehci_hcd *ehci)
+{
+ struct ehci_itd *itd, *n;
+
+ list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
+ struct ehci_iso_stream *stream = itd->stream;
+ itd->stream = NULL;
+ list_move(&itd->itd_list, &stream->free_list);
+ iso_stream_put(ehci, stream);
+ }
+}
+
+/*-------------------------------------------------------------------------*/
+
static void
scan_periodic (struct ehci_hcd *ehci)
{
@@ -2115,10 +2144,17 @@ scan_periodic (struct ehci_hcd *ehci)
* Touches as few pages as possible: cache-friendly.
*/
now_uframe = ehci->next_uframe;
- if (HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
+ if (HC_IS_RUNNING(ehci_to_hcd(ehci)->state)) {
clock = ehci_readl(ehci, &ehci->regs->frame_index);
- else
+ clock_frame = (clock >> 3) % ehci->periodic_size;
+ } else {
clock = now_uframe + mod - 1;
+ clock_frame = -1;
+ }
+ if (ehci->clock_frame != clock_frame) {
+ free_cached_itd_list(ehci);
+ ehci->clock_frame = clock_frame;
+ }
clock %= mod;
clock_frame = clock >> 3;
@@ -2277,6 +2313,10 @@ restart:
/* rescan the rest of this frame, then ... */
clock = now;
clock_frame = clock >> 3;
+ if (ehci->clock_frame != clock_frame) {
+ free_cached_itd_list(ehci);
+ ehci->clock_frame = clock_frame;
+ }
} else {
now_uframe++;
now_uframe %= mod;
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index fb7054ccf4fc..262b00c9b334 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -87,6 +87,10 @@ struct ehci_hcd { /* one per controller */
int next_uframe; /* scan periodic, start here */
unsigned periodic_sched; /* periodic activity count */
+ /* list of itds completed while clock_frame was still active */
+ struct list_head cached_itd_list;
+ unsigned clock_frame;
+
/* per root hub port */
unsigned long reset_done [EHCI_MAX_ROOT_PORTS];
@@ -220,6 +224,8 @@ timer_action (struct ehci_hcd *ehci, enum ehci_timer_action action)
}
}
+static void free_cached_itd_list(struct ehci_hcd *ehci);
+
/*-------------------------------------------------------------------------*/
#include <linux/usb/ehci_def.h>