firewire: ohci: Make cycleMatch ISO transmission work

Calling the START_ISO ioctl with a nonnegative cycle paramater has
never worked.  Last night I got around to figuring out why.  Most of
this patch is a big comment explaining why we enable an interrupt
source then don't actually do anything when we get one.  As the
comment says, we should do more, but we don't have a way to tell
userspace what happened. . .

Signed-off-by: Jay Fenlason <fenlason@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (edited comment)

1 files changed, 15 insertions, 1 deletions

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 5d524254499e..c07cfada190a 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -275,7 +275,7 @@ static void log_irqs(u32 evt)
             !(evt & OHCI1394_busReset))
                 return;
 
-        fw_notify("IRQ %08x%s%s%s%s%s%s%s%s%s%s%s%s%s\n", evt,
+        fw_notify("IRQ %08x%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n", evt,
             evt & OHCI1394_selfIDComplete       ? " selfID"             : "",
             evt & OHCI1394_RQPkt                ? " AR_req"             : "",
             evt & OHCI1394_RSPkt                ? " AR_resp"            : "",
@@ -286,6 +286,7 @@ static void log_irqs(u32 evt)
             evt & OHCI1394_postedWriteErr       ? " postedWriteErr"     : "",
             evt & OHCI1394_cycleTooLong         ? " cycleTooLong"       : "",
             evt & OHCI1394_cycle64Seconds       ? " cycle64Seconds"     : "",
+            evt & OHCI1394_cycleInconsistent    ? " cycleInconsistent"  : "",
             evt & OHCI1394_regAccessFail        ? " regAccessFail"      : "",
             evt & OHCI1394_busReset             ? " busReset"           : "",
             evt & ~(OHCI1394_selfIDComplete | OHCI1394_RQPkt |
@@ -293,6 +294,7 @@ static void log_irqs(u32 evt)
                     OHCI1394_respTxComplete | OHCI1394_isochRx |
                     OHCI1394_isochTx | OHCI1394_postedWriteErr |
                     OHCI1394_cycleTooLong | OHCI1394_cycle64Seconds |
+                    OHCI1394_cycleInconsistent |
                     OHCI1394_regAccessFail | OHCI1394_busReset)
                                                 ? " ?"                  : "");
 }
@@ -1439,6 +1441,17 @@ static irqreturn_t irq_handler(int irq, void *data)
                           OHCI1394_LinkControl_cycleMaster);
         }
 
+        if (unlikely(event & OHCI1394_cycleInconsistent)) {
+                /*
+                 * We need to clear this event bit in order to make
+                 * cycleMatch isochronous I/O work.  In theory we should
+                 * stop active cycleMatch iso contexts now and restart
+                 * them at least two cycles later.  (FIXME?)
+                 */
+                if (printk_ratelimit())
+                        fw_notify("isochronous cycle inconsistent\n");
+        }
+
         if (event & OHCI1394_cycle64Seconds) {
                 cycle_time = reg_read(ohci, OHCI1394_IsochronousCycleTimer);
                 if ((cycle_time & 0x80000000) == 0)
@@ -1528,6 +1541,7 @@ static int ohci_enable(struct fw_card *card, u32 *config_rom, size_t length)
                   OHCI1394_reqTxComplete | OHCI1394_respTxComplete |
                   OHCI1394_isochRx | OHCI1394_isochTx |
                   OHCI1394_postedWriteErr | OHCI1394_cycleTooLong |
+                  OHCI1394_cycleInconsistent |
                   OHCI1394_cycle64Seconds | OHCI1394_regAccessFail |
                   OHCI1394_masterIntEnable);
         if (param_debug & OHCI_PARAM_DEBUG_BUSRESETS)