IEEE 1394 subsystem patch:

- Work around JMicron initialization quirk.
     Affected isochronous transmission, e.g. audio via FFADO or ALSA.
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Merge tag 'firewire-update' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394

Pull firewire fix from Stefan Richter:
 "Work around JMicron initialization quirk, which ffected isochronous
  transmission, e.g. audio via FFADO or ALSA"

* tag 'firewire-update' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: ohci: fix JMicron JMB38x IT context discovery

drivers/firewire/ohci.c

@@ -3675,6 +3675,11 @@ static int pci_probe(struct pci_dev *dev,
 
 	reg_write(ohci, OHCI1394_IsoXmitIntMaskSet, ~0);
 	ohci->it_context_support = reg_read(ohci, OHCI1394_IsoXmitIntMaskSet);
+	/* JMicron JMB38x often shows 0 at first read, just ignore it */
+	if (!ohci->it_context_support) {
+		ohci_notice(ohci, "overriding IsoXmitIntMask\n");
+		ohci->it_context_support = 0xf;
+	}
 	reg_write(ohci, OHCI1394_IsoXmitIntMaskClear, ~0);
 	ohci->it_context_mask = ohci->it_context_support;
 	ohci->n_it = hweight32(ohci->it_context_mask);