Messages in this thread Patch in this message | | | Date | Sat, 8 Nov 2008 12:03:28 +0100 (CET) | From | Stefan Richter <> | Subject | [PATCH] firewire: detect and log TSB81BA3 erratum |
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While testing a larger 1394b bus, I saw the following Texas Instruments TSB81BA3 hardware bug at work: On a 1394b-only bus with three or more PHYs and differing cable lengths or differing hop speeds, the PHYs repeatedly cause bus resets during traffic on the bus, as documented in TI's "TSB81BA3 Errata (Rev. C)" SLLZ015C. These resets cause massive I/O failures.
Self-ID complete events after such resets consistently show more than one self-ID zero packet with i bit set ( = initiated reset). If this happens, emit a warning in dmesg and suggest hardware workarounds to the user. (There is no software workaround.)
The hardware bug is fixed in TSB81BA3 revision D but there are probably many FireWire 800 products out there which have a buggy version of this chip.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> --- drivers/firewire/fw-topology.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
Index: linux/drivers/firewire/fw-topology.c =================================================================== --- linux.orig/drivers/firewire/fw-topology.c +++ linux/drivers/firewire/fw-topology.c @@ -179,7 +179,7 @@ static struct fw_node *build_tree(struct struct list_head stack, *h; u32 *next_sid, *end, q; int i, port_count, child_port_count, phy_id, parent_count, stack_depth; - int gap_count; + int gap_count, reset_initiators; bool beta_repeaters_present; local_node = NULL; @@ -190,6 +190,7 @@ static struct fw_node *build_tree(struct phy_id = 0; irm_node = NULL; gap_count = SELF_ID_GAP_COUNT(*sid); + reset_initiators = 0; beta_repeaters_present = false; while (sid < end) { @@ -285,6 +286,8 @@ static struct fw_node *build_tree(struct list_add_tail(&node->link, &stack); stack_depth += 1 - child_port_count; + reset_initiators += SELF_ID_PHY_INITIATOR(q); + if (node->phy_speed == SCODE_BETA && parent_count + child_port_count > 1) beta_repeaters_present = true; @@ -307,6 +310,14 @@ static struct fw_node *build_tree(struct card->gap_count = gap_count; card->beta_repeaters_present = beta_repeaters_present; + if (reset_initiators != 1) { + fw_error("%d bus reset initiators, hardware bug?\n", + reset_initiators); + if (beta_repeaters_present) + fw_error("try cables with matched length " + "or add a 1394a node\n"); + } + return local_node; } -- Stefan Richter -=====-==--- =-== -=--- http://arcgraph.de/sr/
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