ohci1394: clean up asynchronous and physical request filters programming

Various cleanups of how ohci1394 programs AsynchronousRequestFilter,
PhysicalRequestFilter, and physUpperBoundOffset. In particular, do not
rewrite registers within the bus reset interrupt handler if bus resets
do not affect the registers in the first place.

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

Index: linux-2.6.16-rc2/drivers/ieee1394/ohci1394.c
===================================================================
--- linux-2.6.16-rc2.orig/drivers/ieee1394/ohci1394.c	2006-02-04 20:37:57.000000000 +0100
+++ linux-2.6.16-rc2/drivers/ieee1394/ohci1394.c	2006-02-05 20:55:52.000000000 +0100
@@ -544,12 +544,19 @@ static void ohci_initialize(struct ti_oh
 	/* Initialize IR Legacy DMA channel mask */
 	ohci->ir_legacy_channels = 0;
 
-	/*
-	 * Accept AT requests from all nodes. This probably
-	 * will have to be controlled from the subsystem
-	 * on a per node basis.
-	 */
-	reg_write(ohci,OHCI1394_AsReqFilterHiSet, 0x80000000);
+	/* Accept AR requests from all nodes */
+	reg_write(ohci, OHCI1394_AsReqFilterHiSet, 0x80000000);
+
+	/* Set the address range of the physical response unit.
+	 * Most controllers do not implement it as a writable register though.
+	 * They will keep a hardwired offset of 0x00010000 and show 0x0 as
+	 * register content.
+	 * To actually enable physical responses is the job of our interrupt
+	 * handler which programs the physical request filter. */
+	reg_write(ohci, OHCI1394_PhyUpperBound, 0xffff0000);
+
+	DBGMSG("physUpperBoundOffset=%08x",
+	       reg_read(ohci, OHCI1394_PhyUpperBound));
 
 	/* Specify AT retries */
 	reg_write(ohci, OHCI1394_ATRetries,
@@ -2516,26 +2523,20 @@ static irqreturn_t ohci_irq_handler(int 
 			reg_write(ohci, OHCI1394_IntMaskSet, OHCI1394_busReset);
 			spin_unlock_irqrestore(&ohci->event_lock, flags);
 
-			/* Accept Physical requests from all nodes. */
-			reg_write(ohci,OHCI1394_AsReqFilterHiSet, 0xffffffff);
-			reg_write(ohci,OHCI1394_AsReqFilterLoSet, 0xffffffff);
-
 			/* Turn on phys dma reception.
 			 *
 			 * TODO: Enable some sort of filtering management.
 			 */
 			if (phys_dma) {
-				reg_write(ohci,OHCI1394_PhyReqFilterHiSet, 0xffffffff);
-				reg_write(ohci,OHCI1394_PhyReqFilterLoSet, 0xffffffff);
-				reg_write(ohci,OHCI1394_PhyUpperBound, 0xffff0000);
-			} else {
-				reg_write(ohci,OHCI1394_PhyReqFilterHiSet, 0x00000000);
-				reg_write(ohci,OHCI1394_PhyReqFilterLoSet, 0x00000000);
+				reg_write(ohci, OHCI1394_PhyReqFilterHiSet,
+					  0xffffffff);
+				reg_write(ohci, OHCI1394_PhyReqFilterLoSet,
+					  0xffffffff);
 			}
 
 			DBGMSG("PhyReqFilter=%08x%08x",
-			       reg_read(ohci,OHCI1394_PhyReqFilterHiSet),
-			       reg_read(ohci,OHCI1394_PhyReqFilterLoSet));
+			       reg_read(ohci, OHCI1394_PhyReqFilterHiSet),
+			       reg_read(ohci, OHCI1394_PhyReqFilterLoSet));
 
 			hpsb_selfid_complete(host, phyid, isroot);
 		} else