]> pilppa.com Git - linux-2.6-omap-h63xx.git/commitdiff
USB: EHCI: slow down ITD reuse
authorKarsten Wiese <fzu@wemgehoertderstaat.de>
Mon, 9 Feb 2009 00:07:58 +0000 (16:07 -0800)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 27 Feb 2009 22:40:50 +0000 (14:40 -0800)
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>
drivers/usb/host/ehci-hcd.c
drivers/usb/host/ehci-mem.c
drivers/usb/host/ehci-sched.c
drivers/usb/host/ehci.h

index 4725d15d096f559fc833d0e0f6323bcff4aa7631..e551bb38852be35eefeb532a23c260ecff6109ff 100644 (file)
@@ -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
index 0431397836f65e859f1a2b1829f418fa3697f65d..10d52919abbb1513feefe95ecaa5c5aa518a7443 100644 (file)
@@ -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;
index a081ee65bde6d933f3f2000c67028d461ece27c7..07bcb931021b48a9b00ffeac887288448c7d696e 100644 (file)
@@ -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;
index fb7054ccf4fce90c516397f9923e6195c149768e..262b00c9b334286583d8fb84d394bac07a86a304 100644 (file)
@@ -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>