diff options
Diffstat (limited to 'c/src/lib/libbsp/powerpc/mvme3100/KNOWN_PROBLEMS')
| -rw-r--r-- | c/src/lib/libbsp/powerpc/mvme3100/KNOWN_PROBLEMS | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/powerpc/mvme3100/KNOWN_PROBLEMS b/c/src/lib/libbsp/powerpc/mvme3100/KNOWN_PROBLEMS new file mode 100644 index 0000000000..2178c43206 --- /dev/null +++ b/c/src/lib/libbsp/powerpc/mvme3100/KNOWN_PROBLEMS @@ -0,0 +1,77 @@ +I have observed what seem to be strange +initialization problems with the ethernet +driver: + +I usually configure RTEMS networking by +BOOTP (the problem has nothing to do with +BOOTP but I just want to describe my +environment). Sometimes (it can actually +happen quite frequently, like 1 out of 4 +attempts but since yesterday when I decided +to hunt this down more systematically +the problem seems to have gone - typical!) +networking fails to initialize properly: + +BOOTP requests are sent (to the MAC), +TX interrupts occur and the TX MIB +counters increment - i.e., everything +seems normal but no data can be seen on +the wire. Also, even though we are on +a quite busy network, the receiver +doesn't see anything, i.e., 0 RX +interrupts, RX MIB counters for broadcast +packets remain steady at zero etc. +In brief, everyting seems normal at the +MAC and higher layers but no connection +to the wire seems to be established. + +Some further tests reveal (system under +test is in the 'bad' state): + 1 communication with the BCM5461 PHY + is normal. Registers can be read/written + and everything seems normal. In particular, + the link status is reported OK: disconnect + the cable and MII - BMSR bit 1<<2 is clear, + reconnect the cable and BMSR[2] is set. + Restart autoneg, the link goes and comes + back after a short while. + 2 setting the loopback bit in the TSEC's + MACCFG1 register correctly feeds packets + back into the RX, RX MIB counters now + increment and indicate data flow. + There are RX interrupts and all indicates + (I haven't actually looked at RX packet + data) that the RX would work normally. + After switching MACCFG1[LOOP_BACK] off + no RX traffic can be seen anymore. + 3 resetting the PHY (BMCR = 0x8000) and/or + restarting autoneg (BMCR = 0x1200) seems + to perform the desired action (registers + take on expected values) but still no luck + with communication all the way through + to the wire. + +Especially point 2 seems to indicate that +the problem is likely to be between the +wire and the MAC somewhere but re-setting +the PHY doesn't change things. Analysis is +much complicated by the fact that there +is no documentation on the BCM5461 chip +available. + +Noteworthy is also that if the system +initializes OK then it continues to work +normally; if initialization fails then +only resetting the board and restarting +helps. + +I wanted to test if it makes a difference +if MotLoad used the chip prior to RTEMS +being booted (in case MotLoad did some +magic step during initialization) but +before I could really test this the +problem went away. + +Big Mystery... + +12/12/2007, T.S. |