firewire: net: Use posted writes

Change memory region to ohci "middle address space". This effectively
reduces the number of packets by 50%.

[Stefan R.:]  This eliminates 1394 ack packets and improved throughput
by a few percent in some tests with an S400a connection with and without
gap count optimization.  Since firewire-net taxes the AR-req DMA unit of
a FireWire controller much more than firewire-sbp2 (which uses the
middle address space with PCI posted writes too), this commit also
changes a related error printk into a ratelimited one as a precaution.

Side note:  The IPv4-over-1394 drivers of Mac OS X 10.4, Windows XP SP3,
and the Thesycon 1394 bus driver for Windows all use the middle address
space too.

Signed-off-by: Stephan Gatzka <stephan@gatzka.org>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 399d5926caf7..bffc2ad7ecab 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -2045,7 +2045,8 @@ static irqreturn_t irq_handler(int irq, void *data)
                 reg_read(ohci, OHCI1394_PostedWriteAddressLo);
                 reg_write(ohci, OHCI1394_IntEventClear,
                           OHCI1394_postedWriteErr);
-                fw_error("PCI posted write error\n");
+                if (printk_ratelimit())
+                        fw_error("PCI posted write error\n");
         }
 
         if (unlikely(event & OHCI1394_cycleTooLong)) {