firewire: ohci: optimize iso context checks in the interrupt handler

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>

1 files changed, 19 insertions, 13 deletions

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 29259f3a30bb..01b3bc9154a6 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -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))