firewire: fw-ohci: CycleTooLong interrupt management

The firewire-ohci driver so far lacked the ability to resume cycle
master duty after that condition happened, as added to ohci1394 in Linux
2.6.18 by commit 57fdb58fa5a140bdd52cf4c4ffc30df73676f0a5.  This ports
this patch to fw-ohci.

The "cycle too long" condition has been seen in practice
  - with IIDC cameras if a mode with packets too large for a speed is
    chosen,
  - sporadically when capturing DV on a VIA VT6306 card with ohci1394/
    ieee1394/ raw1394/ dvgrab 2.
    https://bugzilla.redhat.com/show_bug.cgi?id=415841#c7
(This does not fix Fedora bug 415841.)

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/fw-ohci.c

@@ -1079,6 +1079,13 @@ static irqreturn_t irq_handler(int irq, void *data)
 	if (unlikely(event & OHCI1394_postedWriteErr))
 		fw_error("PCI posted write error\n");
 
+	if (unlikely(event & OHCI1394_cycleTooLong)) {
+		if (printk_ratelimit())
+			fw_notify("isochronous cycle too long\n");
+		reg_write(ohci, OHCI1394_LinkControlSet,
+			  OHCI1394_LinkControl_cycleMaster);
+	}
+
 	if (event & OHCI1394_cycle64Seconds) {
 		cycle_time = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
 		if ((cycle_time & 0x80000000) == 0)
@@ -1152,8 +1159,8 @@ static int ohci_enable(struct fw_card *card, u32 *config_rom, size_t length)
 		  OHCI1394_RQPkt | OHCI1394_RSPkt |
 		  OHCI1394_reqTxComplete | OHCI1394_respTxComplete |
 		  OHCI1394_isochRx | OHCI1394_isochTx |
-		  OHCI1394_postedWriteErr | OHCI1394_cycle64Seconds |
-		  OHCI1394_masterIntEnable);
+		  OHCI1394_postedWriteErr | OHCI1394_cycleTooLong |
+		  OHCI1394_cycle64Seconds | OHCI1394_masterIntEnable);
 
 	/* Activate link_on bit and contender bit in our self ID packets.*/
 	if (ohci_update_phy_reg(card, 4, 0,