firewire: ohci: optimize iso context checks in the interrupt handler
Clemens Ladisch [Tue, 30 Nov 2010 07:25:05 +0000 (08:25 +0100)]
When the isochRx/isochTx bit is clear, we do not need to read the
corresponding iso interrupt event register.

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

drivers/firewire/ohci.c

index 29259f3..01b3bc9 100644 (file)
@@ -1813,22 +1813,28 @@ static irqreturn_t irq_handler(int irq, void *data)
        if (event & OHCI1394_respTxComplete)
                tasklet_schedule(&ohci->at_response_ctx.tasklet);
 
-       iso_event = reg_read(ohci, OHCI1394_IsoRecvIntEventClear);
-       reg_write(ohci, OHCI1394_IsoRecvIntEventClear, iso_event);
-
-       while (iso_event) {
-               i = ffs(iso_event) - 1;
-               tasklet_schedule(&ohci->ir_context_list[i].context.tasklet);
-               iso_event &= ~(1 << i);
+       if (event & OHCI1394_isochRx) {
+               iso_event = reg_read(ohci, OHCI1394_IsoRecvIntEventClear);
+               reg_write(ohci, OHCI1394_IsoRecvIntEventClear, iso_event);
+
+               while (iso_event) {
+                       i = ffs(iso_event) - 1;
+                       tasklet_schedule(
+                               &ohci->ir_context_list[i].context.tasklet);
+                       iso_event &= ~(1 << i);
+               }
        }
 
-       iso_event = reg_read(ohci, OHCI1394_IsoXmitIntEventClear);
-       reg_write(ohci, OHCI1394_IsoXmitIntEventClear, iso_event);
+       if (event & OHCI1394_isochTx) {
+               iso_event = reg_read(ohci, OHCI1394_IsoXmitIntEventClear);
+               reg_write(ohci, OHCI1394_IsoXmitIntEventClear, iso_event);
 
-       while (iso_event) {
-               i = ffs(iso_event) - 1;
-               tasklet_schedule(&ohci->it_context_list[i].context.tasklet);
-               iso_event &= ~(1 << i);
+               while (iso_event) {
+                       i = ffs(iso_event) - 1;
+                       tasklet_schedule(
+                               &ohci->it_context_list[i].context.tasklet);
+                       iso_event &= ~(1 << i);
+               }
        }
 
        if (unlikely(event & OHCI1394_regAccessFail))