USB: EHCI: remove ASS/PSS polling timeout (55bcdce8) · Commits · 戴 / test

This patch (as1647) attempts to work around a problem that seems to affect some nVidia EHCI controllers. They sometimes take a very long time to turn off their async or periodic schedules. I don't know if this is a result of other problems, but in any case it seems wise not to depend on schedule enables or disables taking effect in any specific length of time. The patch removes the existing 20-ms timeout for enabling and disabling the schedules. The driver will now continue to poll the schedule state at 1-ms intervals until the controller finally decides to obey the most recent command issued by the driver. Just in case this hides a problem, a debugging message will be logged if the controller takes longer than 20 polls. I don't know if this will actually fix anything, but it can't hurt. Signed-off-by:

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

Piergiorgio Sartor <piergiorgio.sartor@nexgo.de> CC: <stable@vger.kernel.org> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-timer.c

+15 −14

Original line number	Diff line number	Diff line
		@@ -113,14 +113,15 @@ static void ehci_poll_ASS(struct ehci_hcd *ehci)

		if (want != actual) {

		/* Poll again later, but give up after about 20 ms */
		if (ehci->ASS_poll_count++ < 20) {
		/* Poll again later */
		ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
		++ehci->ASS_poll_count;
		return;
		}
		ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n",
		want, actual);
		}

		if (ehci->ASS_poll_count > 20)
		ehci_dbg(ehci, "ASS poll count reached %d\n",
		ehci->ASS_poll_count);
		ehci->ASS_poll_count = 0;

		/* The status is up-to-date; restart or stop the schedule as needed */
		@@ -159,14 +160,14 @@ static void ehci_poll_PSS(struct ehci_hcd *ehci)

		if (want != actual) {

		/* Poll again later, but give up after about 20 ms */
		if (ehci->PSS_poll_count++ < 20) {
		/* Poll again later */
		ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
		return;
		}
		ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n",
		want, actual);
		}

		if (ehci->PSS_poll_count > 20)
		ehci_dbg(ehci, "PSS poll count reached %d\n",
		ehci->PSS_poll_count);
		ehci->PSS_poll_count = 0;

		/* The status is up-to-date; restart or stop the schedule as needed */

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