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>
diff --git a/drivers/ieee1394/nodemgr.c b/drivers/ieee1394/nodemgr.c
index 082c7fd..948f1b8 100644
--- a/drivers/ieee1394/nodemgr.c
+++ b/drivers/ieee1394/nodemgr.c
@@ -38,6 +38,7 @@
struct hpsb_host *host;
nodeid_t nodeid;
unsigned int generation;
+ unsigned int speed_unverified:1;
};
@@ -57,23 +58,75 @@
return NULL;
}
+/*
+ * Correct the speed map entry. This is necessary
+ * - for nodes with link speed < phy speed,
+ * - for 1394b nodes with negotiated phy port speed < IEEE1394_SPEED_MAX.
+ * A possible speed is determined by trial and error, using quadlet reads.
+ */
+static int nodemgr_check_speed(struct nodemgr_csr_info *ci, u64 addr,
+ quadlet_t *buffer)
+{
+ quadlet_t q;
+ u8 i, *speed, old_speed, good_speed;
+ int ret;
+
+ speed = ci->host->speed + NODEID_TO_NODE(ci->nodeid);
+ old_speed = *speed;
+ good_speed = IEEE1394_SPEED_MAX + 1;
+
+ /* Try every speed from S100 to old_speed.
+ * If we did it the other way around, a too low speed could be caught
+ * if the retry succeeded for some other reason, e.g. because the link
+ * just finished its initialization. */
+ for (i = IEEE1394_SPEED_100; i <= old_speed; i++) {
+ *speed = i;
+ ret = hpsb_read(ci->host, ci->nodeid, ci->generation, addr,
+ &q, sizeof(quadlet_t));
+ if (ret)
+ break;
+ *buffer = q;
+ good_speed = i;
+ }
+ if (good_speed <= IEEE1394_SPEED_MAX) {
+ HPSB_DEBUG("Speed probe of node " NODE_BUS_FMT " yields %s",
+ NODE_BUS_ARGS(ci->host, ci->nodeid),
+ hpsb_speedto_str[good_speed]);
+ *speed = good_speed;
+ ci->speed_unverified = 0;
+ return 0;
+ }
+ *speed = old_speed;
+ return ret;
+}
static int nodemgr_bus_read(struct csr1212_csr *csr, u64 addr, u16 length,
void *buffer, void *__ci)
{
struct nodemgr_csr_info *ci = (struct nodemgr_csr_info*)__ci;
- int i, ret = 0;
+ int i, ret;
for (i = 1; ; i++) {
ret = hpsb_read(ci->host, ci->nodeid, ci->generation, addr,
buffer, length);
- if (!ret || i == 3)
+ if (!ret) {
+ ci->speed_unverified = 0;
+ break;
+ }
+ /* Give up after 3rd failure. */
+ if (i == 3)
break;
+ /* The ieee1394_core guessed the node's speed capability from
+ * the self ID. Check whether a lower speed works. */
+ if (ci->speed_unverified && length == sizeof(quadlet_t)) {
+ ret = nodemgr_check_speed(ci, addr, buffer);
+ if (!ret)
+ break;
+ }
if (msleep_interruptible(334))
return -EINTR;
}
-
return ret;
}
@@ -1204,6 +1257,8 @@
ci->host = host;
ci->nodeid = nodeid;
ci->generation = generation;
+ ci->speed_unverified =
+ host->speed[NODEID_TO_NODE(nodeid)] > IEEE1394_SPEED_100;
/* We need to detect when the ConfigROM's generation has changed,
* so we only update the node's info when it needs to be. */