>I don't know. And I'm starting to think that we don't need to retry
>for such a long time -- persistent errors should be handled by the
>higher-level drivers. Perhaps a count of 32 or so would be enough.
I think so, too.
I think that it is difficult to put out a well-grounded
numerical value even if I thinks any further. If we usually
use it, I guess that low probability of unplugging a device
while accessing to a device. Because it is thought that CPU
is not completely occupied only with retrying, I think that
no problem. I want to finish the modification by the
retrying of 32 times. I changed to 32 from 255.
How do you think?
>You did not understand my question. What happens if ehci_hcd is
>_loaded_ and the device is running at full speed or low speed because
>it is a USB-1.1 device plugged into a high-speed hub?
I tested following case.
=== case1 ===
root hub : plugged "USB flash" and "high-speed hub"
high-speed hub : plugged "USB mouse"
=== case2 ===
root hub : plugged "high-speed hub"
high-speed hub : plugged "USB flash" and "USB mouse"
USB mouse unplugged while accessing USB flash. In both
cases, XactErr didn't occurred. Though it doesn't relate to
the question, when two high-speed device plugged into
high-speed hub, error didn't occur.
best regards
KoichiroSaito
diff -uprN linux-2.6.29-rc2-git1.org/drivers/usb/host/ehci-q.c linux-2.6.29-rc2-git1/drivers/usb/host/ehci-q.c
--- linux-2.6.29-rc2-git1.org/drivers/usb/host/ehci-q.c 2008-12-25 08:26:37.000000000 +0900
+++ linux-2.6.29-rc2-git1/drivers/usb/host/ehci-q.c 2009-01-27 23:57:07.000000000 +0900
@@ -333,12 +333,39 @@ qh_completions (struct ehci_hcd *ehci, s
token = hc32_to_cpu(ehci, qtd->hw_token);
/* always clean up qtds the hc de-activated */
+ retry_xacterr:
if ((token & QTD_STS_ACTIVE) == 0) {
/* on STALL, error, and short reads this urb must
* complete and all its qtds must be recycled.
*/
if ((token & QTD_STS_HALT) != 0) {
+
+ /* retry transaction errors until we
+ * reach the software xacterr limit
+ */
+ if ((token & QTD_STS_XACT) &&
+ !QTD_CERR(token) &&
+ --qh->xacterrs > 0) {
+ ehci_dbg(ehci,
+ "detected XactErr len %d/%d retry %d\n",
+ qtd->length - QTD_LENGTH(token), qtd->length,
+ QH_XACTERR_MAX - qh->xacterrs);
+
+ /* reset the token in the qtd and the
+ * qh overlay (which still contains
+ * the qtd) so that we pick up from
+ * where we left off
+ */
+ token &= ~QTD_STS_HALT;
+ token |= QTD_STS_ACTIVE |
+ (EHCI_TUNE_CERR << 10);
+ qtd->hw_token = cpu_to_hc32(ehci,
+ token);
+ wmb();
+ qh->hw_token = cpu_to_hc32(ehci, token);
+ goto retry_xacterr;
+ }
stopped = 1;
/* magic dummy for some short reads; qh won't advance.
@@ -355,6 +382,10 @@ qh_completions (struct ehci_hcd *ehci, s
& EHCI_LIST_END(ehci))) {
stopped = 1;
goto halt;
+
+ /* reinit the xacterr counter for the next qtd */
+ } else {
+ qh->xacterrs = QH_XACTERR_MAX;
}
/* stop scanning when we reach qtds the hc is using */
diff -uprN linux-2.6.29-rc2-git1.org/drivers/usb/host/ehci.h linux-2.6.29-rc2-git1/drivers/usb/host/ehci.h
--- linux-2.6.29-rc2-git1.org/drivers/usb/host/ehci.h 2009-01-24 01:35:56.000000000 +0900
+++ linux-2.6.29-rc2-git1/drivers/usb/host/ehci.h 2009-01-27 20:02:08.000000000 +0900
@@ -370,6 +370,9 @@ struct ehci_qh {
#define QH_STATE_UNLINK_WAIT 4 /* LINKED and on reclaim q */
#define QH_STATE_COMPLETING 5 /* don't touch token.HALT */
+ u8 xacterrs; /* XactErr retry counter */
+#define QH_XACTERR_MAX 32 /* XactErr retry limit */
+
/* periodic schedule info */
u8 usecs; /* intr bandwidth */
u8 gap_uf; /* uframes split/csplit gap */
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
