This patch (as1257) revises the way ehci-hcd detects STALLs. The
logic has to be a little peculiar, because there's no hardware status
bit specifically meant to indicate a STALL. You just have to guess
that a STALL was received if none of the fatal error bits are set and
the transfer stopped before all its retries were used up. The
existing code doesn't quite do this, and its logic is more tortuous
than necessary.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
CC: David Brownell <david-b@xxxxxxxxxxx>
---
This is a pretty obscure issue. The patch can wait for 2.6.32 or it
can go in 2.6.31, your choice.
Index: usb-2.6/drivers/usb/host/ehci-q.c
===================================================================
--- usb-2.6.orig/drivers/usb/host/ehci-q.c
+++ usb-2.6/drivers/usb/host/ehci-q.c
@@ -214,6 +214,14 @@ static int qtd_copy_status (
if (token & QTD_STS_BABBLE) {
/* FIXME "must" disable babbling device's port too */
status = -EOVERFLOW;
+ /* CERR nonzero + halt --> stall */
+ } else if (QTD_CERR(token)) {
+ status = -EPIPE;
+
+ /* In theory, more than one of the following bits can be set
+ * since they are sticky and the transaction is retried.
+ * Which to test first is rather arbitrary.
+ */
} else if (token & QTD_STS_MMF) {
/* fs/ls interrupt xfer missed the complete-split */
status = -EPROTO;
@@ -222,21 +230,15 @@ static int qtd_copy_status (
? -ENOSR /* hc couldn't read data */
: -ECOMM; /* hc couldn't write data */
} else if (token & QTD_STS_XACT) {
- /* timeout, bad crc, wrong PID, etc; retried */
- if (QTD_CERR (token))
- status = -EPIPE;
- else {
- ehci_dbg (ehci, "devpath %s ep%d%s 3strikes\n",
- urb->dev->devpath,
- usb_pipeendpoint (urb->pipe),
- usb_pipein (urb->pipe) ? "in" : "out");
- status = -EPROTO;
- }
- /* CERR nonzero + no errors + halt --> stall */
- } else if (QTD_CERR (token))
- status = -EPIPE;
- else /* unknown */
+ /* timeout, bad CRC, wrong PID, etc */
+ ehci_dbg(ehci, "devpath %s ep%d%s 3strikes\n",
+ urb->dev->devpath,
+ usb_pipeendpoint(urb->pipe),
+ usb_pipein(urb->pipe) ? "in" : "out");
+ status = -EPROTO;
+ } else { /* unknown */
status = -EPROTO;
+ }
ehci_vdbg (ehci,
"dev%d ep%d%s qtd token %08x --> status %d\n",
--
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