From: Karsten Wiese <fzu@xxxxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxxx: comment fixups ]
Signed-off-by: Karsten Wiese <fzu@xxxxxxxxxxxxxxxxxxxxx>
Tested-by: Philippe Carriere <philippe-f.carriere@xxxxxxxxxx>
Tested-by: Federico Briata <federicobriata@xxxxxxxxx>
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
---
Suitable for 2.6.28-stable too, it seems ...
drivers/usb/host/ehci-hcd.c | 2 +
drivers/usb/host/ehci-mem.c | 1
drivers/usb/host/ehci-sched.c | 56 ++++++++++++++++++++++++++++++++++------
drivers/usb/host/ehci.h | 6 ++++
4 files changed, 57 insertions(+), 8 deletions(-)
--- 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
--- 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_q
static void ehci_mem_cleanup (struct ehci_hcd *ehci)
{
+ free_cached_itd_list(ehci);
if (ehci->async)
qh_put (ehci->async);
ehci->async = NULL;
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1006,7 +1006,8 @@ iso_stream_put(struct ehci_hcd *ehci, st
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 "
@@ -1657,14 +1658,28 @@ 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;
}
@@ -2105,6 +2120,20 @@ 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)
{
@@ -2119,10 +2148,17 @@ 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;
@@ -2281,6 +2317,10 @@ 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;
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -87,6 +87,10 @@ struct ehci_hcd { /* one per controlle
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, enu
}
}
+static void free_cached_itd_list(struct ehci_hcd *ehci);
+
/*-------------------------------------------------------------------------*/
#include <linux/usb/ehci_def.h>
--
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