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Commit ba516de3 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: EHCI: check for STALL before other errors 



This patch (as1257) revises the way ehci-hcd detects STALLs.  The
logic is 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 the BABBLE bit (which is fatal) isn't set and
the transfer stopped before all its retries were used up.

The existing code doesn't do this properly, because it tests for MMF
(Missed MicroFrame) and DBE (Data Buffer Error) before testing the
retry counter.  Thus, if a transaction gets either MMF or DBE the
corresponding flag is set and the transaction is retried.  If the
second attempt receives a STALL then -EPIPE is the correct return
value.  But the existing code would see the MMF or DBE flag instead
and return -EPROTO, -ENOSR, or -ECOMM.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Acked-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 914b7012

drivers/usb/host/ehci-q.c

+16 −14
Original line number Diff line number Diff line
@@ -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 {

			/* 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;

			}

		/* CERR nonzero + no errors + halt --> stall */

		} else if (QTD_CERR (token))

			status = -EPIPE;

		else	/* unknown */

		} else {	/* unknown */

			status = -EPROTO;

		}



		ehci_vdbg (ehci,

			"dev%d ep%d%s qtd token %08x --> status %d\n",