ieee1394: support for slow links or slow 1394b phy ports

Add support for the following types of hardware:
 + nodes that have a link speed < PHY speed
 + 1394b PHYs that are less than S800 capable
 + 1394b/1394a adapter cable between two 1394b PHYs
Also, S1600 and S3200 are now supported if IEEE1394_SPEED_MAX is raised.

A probing function is added to nodemgr's config ROM fetching routine
which adjusts the allowable speed if an access problem was encountered.
Pros and Cons of the approach:
 + minimum code footprint to support this less widely used hardware
 + nearly no overhead for unaffected hardware
 - ineffective before nodemgr began to read the ROM of affected nodes
 - ineffective if ieee1394 is loaded with disable_nodemgr=1
The speed map CSRs which are published to the bus are not touched by the
patch.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Hakan Ardo <hakan@debian.org>
Cc: Calculex <linux@calculex.com>
Cc: Robert J. Kosinski <robk@cmcherald.com>
Signed-off-by: Ben Collins <bcollins@ubuntu.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/ieee1394/eth1394.c b/drivers/ieee1394/eth1394.c
index 30fa0d43a43a..b2d2c4dd075b 100644
--- a/drivers/ieee1394/eth1394.c
+++ b/drivers/ieee1394/eth1394.c
@@ -502,10 +502,8 @@ static void ether1394_reset_priv (struct net_device *dev, int set_mtu)
 
         /* Determine speed limit */
         for (i = 0; i < host->node_count; i++)
-                if (max_speed > host->speed_map[NODEID_TO_NODE(host->node_id) *
-                                                64 + i])
-                        max_speed = host->speed_map[NODEID_TO_NODE(host->node_id) *
-                                                    64 + i];
+                if (max_speed > host->speed[i])
+                        max_speed = host->speed[i];
         priv->bc_sspd = max_speed;
 
         /* We'll use our maxpayload as the default mtu */