From: Stephan Gatzka <stephan@gatzka.org>
Date: Mon, 26 Sep 2011 19:44:30 +0000 (+0200)
Subject: firewire: net: Use posted writes
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a74477db9171e677b7a37b89e6e0ac8a15ba1f26;p=linux-beck.git

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>
---

diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index d1fad1fb17e2..a20f45b1e7e5 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -1121,17 +1121,12 @@ static int fwnet_broadcast_start(struct fwnet_device *dev)
 	unsigned u;
 
 	if (dev->local_fifo == FWNET_NO_FIFO_ADDR) {
-		/* outside OHCI posted write area? */
-		static const struct fw_address_region region = {
-			.start = 0xffff00000000ULL,
-			.end   = CSR_REGISTER_BASE,
-		};
-
 		dev->handler.length = 4096;
 		dev->handler.address_callback = fwnet_receive_packet;
 		dev->handler.callback_data = dev;
 
-		retval = fw_core_add_address_handler(&dev->handler, &region);
+		retval = fw_core_add_address_handler(&dev->handler,
+					&fw_high_memory_region);
 		if (retval < 0)
 			goto failed_initial;
 
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)) {