USB: EHCI: warn on unexpectedly active QH (fc0855f2) · Commits · 戴 / test

This patch adds a new warning message to ehci-hcd. The warning is triggered whenever the driver finds that the hardware has set the Active bit in a QH at a time when the driver expects the QH to be completely idle. Such bugs have been observed by users in the past, and since they can lead to serious problems (such as inability to unlink an URB that never completes), it would be good to know about them when they occur. This won't fix these bugs; that's a bigger job for a later patch. But success isn't guaranteed, since this depends on aspects of the hardware which are not documented in the EHCI spec or for which the spec's recommendations are clearly unworkable. It therefore seems worthwhile to check for these bugs proactively. Signed-off-by:

Alan Stern <stern@rowland.harvard.edu> Reported-by:

Michael Reutman <mreutman@epiqsolutions.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-q.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -132,11 +132,15 @@ qh_refresh (struct ehci_hcd ehci, struct ehci_qh qh)
		* qtd is updated in qh_completions(). Update the QH
		* overlay here.
		*/
		if (qh->hw->hw_token & ACTIVE_BIT(ehci))
		if (qh->hw->hw_token & ACTIVE_BIT(ehci)) {
		qh->hw->hw_qtd_next = qtd->hw_next;
		else
		if (qh->should_be_inactive)
		ehci_warn(ehci, "qh %p should be inactive!\n", qh);
		} else {
		qh_update(ehci, qh, qtd);
		}
		qh->should_be_inactive = 0;
		}

		/-------------------------------------------------------------------------/

		@@ -438,6 +442,7 @@ qh_completions (struct ehci_hcd ehci, struct ehci_qh qh)
		(hw->hw_token & ACTIVE_BIT(ehci))) {
		token = hc32_to_cpu(ehci, hw->hw_token);
		hw->hw_token &= ~ACTIVE_BIT(ehci);
		qh->should_be_inactive = 1;

		/* An unlink may leave an incomplete
		* async transaction in the TT buffer.

drivers/usb/host/ehci.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -439,6 +439,7 @@ struct ehci_qh {
		unsigned dequeue_during_giveback:1;
		unsigned exception:1; /* got a fault, or an unlink
		was requested */
		unsigned should_be_inactive:1;
		};

		/-------------------------------------------------------------------------/

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