MPC5200 ethernet communication stops unexpected

[Eberhard Stoll]

Hello,
can someone help me?
I have some problem with our MPC5200 board running denx linux kernel 
2.4.25 with ethernet communication.

My problem is that our board stops receiving and transmitting any 
ethernet frames suddenly and unexpected. No pings - nothing is getting 
thru the ethernet any more! The rest of the controller is running well.
This situation is very rare - only a constellation with 6 Controllers 
and a special ethernet communication load leads to this fault - in about 
one day!

When i check how many tx and rx buffers are used in the BestComm buffer 
descriptor ring (via TaskBDInUse() call) which hold pointers to transmit 
and receive data, i see all tx and rx buffers are in use! When i look at 
the FEC Tx Fifo Status Register i get the value 0x00030000. This means 
FEC Tx Fifo empty!
When i check fec Task Control register i see Tx and Rx Task are enabled, 
current Pointer register points to 0xF000828C which belongs to FEC Tx 
BestComm Microcode.
When i now examine the status value of my currently active buffer 
descriptor for Tx task, it shows that this buffer belongs to BestComm.
In my opinion BestComm shold tranfer this buffer to the empty FEC Tx 
Fifo - but it doesn't!
Now the question for me is: WHY?

Do i oversee some bits in the registers/ram locations which lead to this 
situation?
I don't know much about BestComm/FEC, but my conclusion out of this is 
BestComm is stuck somewhere out of some reason. Is this a hardware 
issue? Does someone know? Has someone similar problems?

Can someone help me or check if i'm right with my conclusion (see 
registers and ram locations down)? Or give me a hint where to look further.
Any help is very welcome!

Many Thanks,
Eberhard

PS: I saw this problem only on MPC5200B processors until now. And we use 
BestComm Api 2.2 (the newest denx 2.4.x code for bestcomm)

Here are some registers and ram addresses i collected in this situation:

BTW: I saw BestComm Microcode changing in 16k SRAM after the first 
Ethernet frames were sent. This seems very strange to me - but maybe is 
correct behaviour - i don't know. Does someone of you?
Its the address 0xf00082e8 (in FEC Tx BestComm microcode). After reset 
(no frame sent) the ram at this address is 0x088AC398 after the first(?) 
ethernet frame it's 0x0C8AC398!

=== BestComm registers ===
taskBar         0xF0008000
currentPointer  0xF000828C
endPointer      0x00000000
variablePointer 0xF0008800
IntVect1        0x0000000F
IntVect2        0x0000000F
PtdCntrl        0x00000001
IntPend         0x00000000
IntMask         0xFFFFFFF3
tcr_0 0x0000
tcr_1 0x0000
tcr_2 0xE082
tcr_3 0xC383
tcr_4 0x0000
tcr_5 0x0000
tcr_6 0x0000
tcr_7 0x0000
tcr_8 0x0000
tcr_9 0x0000
tcr_a 0x0000
tcr_b 0x0000
tcr_c 0x0000
tcr_d 0x0000
tcr_e 0x0000
tcr_f 0x0000
IPR0  0x07
IPR1  0x00
IPR2  0x00
IPR3  0x04
IPR4  0x03
IPR5  0x06
IPR6  0x05
IPR7  0x00
IPR8  0x00
IPR9  0x00
IPR10 0x00
IPR11 0x00
IPR12 0x00
IPR13 0x00
IPR14 0x00
IPR15 0x00
IPR16 0x00
IPR17 0x00
IPR18 0x00
IPR19 0x00
IPR20 0x00
IPR21 0x00
IPR22 0x00
IPR23 0x00
IPR24 0x00
IPR25 0x00
IPR26 0x00
IPR27 0x00
IPR28 0x00
IPR29 0x00
IPR30 0x00
IPR31 0x00
task_size0 0x00000000
task_size1 0x00000000
MDEDebug   0x01000008
ADSDebug   0x00000000
Value1     0x00000000
Value2     0x00000000
Control    0x00000000
Status     0x00000000
EU00 0x04155519
EU01 0x00000000
EU02 0x00000000
EU03 0x00000000
EU04 0x00000000
EU05 0x00000000
EU06 0x00000000
EU07 0x00000000
EU10 0x00000000
EU11 0x00000000
EU12 0x00000000
EU13 0x00000000
EU14 0x00000000
EU15 0x00000000
EU16 0x00000000
EU17 0x00000000
EU20 0x00000000
EU21 0x00000000
EU22 0x00000000
EU23 0x00000000
EU24 0x00000000
EU25 0x00000000
EU26 0x00000000
EU27 0x00000000
EU30 0x00000000
EU31 0x00000000
EU32 0x00000000
EU33 0x00000000
EU34 0x00000000
EU35 0x00000000
EU36 0x00000000
EU37 0x00000000

=== Return values of BestComm Api Functions ===
t_tasknum          = 2
TaskBDInUse(tx)    = 256
TaskStatus(tx)     = run (0x00008000)
TaskIntPending(tx) = 0
r_tasknum          = 3
TaskBDInUse(rx)    = 256
TaskStatus(rx)     = run (0x00008000)
TaskIntPending(rx) = 0
TasksGetSramOffset = 0x00002500
task  0:  stop int: 0x00000000
task  1:  stop int: 0x00000000
task  2:  run  int: 0x00000000
task  3:  run  int: 0x00000000
task  4:  stop int: 0x00000000
task  5:  stop int: 0x00000000
task  6:  stop int: 0x00000000
task  7:  stop int: 0x00000000
task  8:  stop int: 0x00000000
task  9:  stop int: 0x00000000
task 10:  stop int: 0x00000000
task 11:  stop int: 0x00000000
task 12:  stop int: 0x00000000
task 13:  stop int: 0x00000000
task 14:  stop int: 0x00000000
task 15:  stop int: 0x00000000

=== FEC Registers ===
fec base addr f0003000
fec_id        0x00000000
ievent        0x08000000
imask         0xF0FE0000
r_des_active  0x00000000
x_des_active  0x00000000
ecntrl        0xF0000002
mii_data      0x5F821200
mii_speed     0x0000001C
mib_control   0x40000000
r_cntrl       0x05EE0024
r_hash        0x8A000000
x_cntrl       0x00000004
paddr1        0x00E0BA90
paddr2        0x07DC8808
op_pause      0x00010020
iaddr1        0x00000000
iaddr2        0x00000000
gaddr1        0x00400000
gaddr2        0x00000000
x_wmrk        0x00000000
rfifo_status  0x214E0000
rfifo_cntrl   0x0F240000
rfifo_lrf_ptr 0x0000005D
rfifo_lwf_ptr 0x0000038D
rfifo_alarm   0x0000030C
rfifo_rdptr   0x0000005D
rfifo_wrptr   0x0000005D
tfifo_status  0x00030000
tfifo_cntrl   0x0F200000
tfifo_lrf_ptr 0x0000023C
tfifo_lwf_ptr 0x0000023C
tfifo_alarm   0x00000100
tfifo_rdptr   0x0000023C
tfifo_wrptr   0x0000023C
reset_cntrl   0x01000000
xmit_fsm      0x03000000

=== FEC driver vars ===
MBAR           0xF0000000
MBAR SIZE      0x10000000
queue_stopped  1
mpc5xxx_bdi_tx 73 (x49)
mpc5xxx_bdi_rx 97 (x61)
adr(tx_fifo_skb)       c0233744
adr(tx_fifo_skb[0])    c0233744
adr(tx_fifo_skb[1])    c0233748
tx_fifo_skb[0]         c2474f20
tx_fifo_skb[1]         c24846e0
sizeof(tx_fifo_skb)    1024
sizeof(tx_fifo_skb[0]) 4
MPC5xxx_FEC_TBD_NUM    256
adr(rx_fifo_skb)       c0233b44
sizeof(rx_fifo_skb)    1024
sizeof(rx_fifo_skb[0]) 4
MPC5xxx_FEC_RBD_NUM    256
full_duplex    1
tx_full        1
r_tasknum      3
t_tasknum      2
r_irq          24
t_irq          23
last_transmit_time 0
last_receive_time 0
phy_id         0x0015F442
phy_id_done    1
phy_status     0x00000000
phy_speed      28
sequence_done  0
link           0
duplex_change  0
link_up        0
old_status     0x00000000

=== BDHead Table ===
TASK #0
[0xC0232D74] = 0x00
[0xC0232D75] = 0x00
[0xC0232D76] = 0x00
[0xC0232D77] = 0x00

TASK #1
[0xC0232D78] = 0x00
[0xC0232D79] = 0x00
[0xC0232D7A] = 0x00
[0xC0232D7B] = 0x00

TASK #2 - tx task
[0xC0232D7C] = 0x00
[0xC0232D7D] = 0x00
[0xC0232D7E] = 0x00
[0xC0232D7F] = 0x49
--> actual tx index: 0x49->73

TASK #3 - rx task
[0xC0232D80] = 0x00
[0xC0232D81] = 0x00
[0xC0232D82] = 0x00
[0xC0232D83] = 0x61
--> actual rx index: 0x61->97

[0xC0232D84] = 0x00
[0xC0232D85] = 0x00
[0xC0232D86] = 0x00
...

=== TaskBDIdxTable ===
TASK#0
numBD      [0xC0232DF4] = 0x0000
numPtr     [0xC0232DF6] = 0x00
apiConfig  [0xC0232DF7] = 0x00
BDTablePtr [0xC0232DF8] = 0x00000000
BDStartPtr [0xC0232DFC] = 0x00000000
currBDInUse[0xC0232E00] = 0x0000
[0xC0232E02] = 0x00
[0xC0232E03] = 0x00

TASK#1
[0xC0232E04] = 0x00
[0xC0232E05] = 0x00
[0xC0232E06] = 0x00
[0xC0232E07] = 0x00
[0xC0232E08] = 0x00
[0xC0232E09] = 0x00
[0xC0232E0A] = 0x00
[0xC0232E0B] = 0x00
[0xC0232E0C] = 0x00
[0xC0232E0D] = 0x00
[0xC0232E0E] = 0x00
[0xC0232E0F] = 0x00
[0xC0232E10] = 0x00
[0xC0232E11] = 0x00
[0xC0232E12] = 0x00
[0xC0232E13] = 0x00

TASK#2 - tx task
numBD      [0xC0232E14] = 0x0100
numPtr     [0xC0232E16] = 0x01
apiConfig  [0xC0232E17] = 0x01
BDTablePtr [0xC0232E18] = 0xF0009D00
BDStartPtr [0xC0232E1C] = 0xF0008814
currBDInUse[0xC0232E20] = 0x0100
[0xC0232E22] = 0x00
[0xC0232E23] = 0x00

TASK#3 - rx task
numBD      [0xC0232E24] = 0x0100
numPtr     [0xC0232E26] = 0x01
apiConfig  [0xC0232E27] = 0x00
BDTablePtr [0xC0232E28] = 0xF0009500
BDStartPtr [0xC0232E2C] = 0xF0008890
currBDInUse[0xC0232E30] = 0x0100
[0xC0232E32] = 0x00
[0xC0232E33] = 0x00

TASK#4
[0xC0232E34] = 0x00
[0xC0232E35] = 0x00
...

=== Tx Descriptor Ring ===
IDX 0x49-(73) is interesting, because active (see BDHeadTable).
So our descriptor is as Addr 0xF0009D00 + (0x49 * 0x8) = 0xF0009F48

IDX 0
[0xF0009D00] = 0x4C00003C
[0xF0009D04] = 0x02475922

IDX 1
[0xF0009D08] = 0x4C00003C
[0xF0009D0C] = 0x02475CA2
...
IDX 72
[0xF0009F40] = 0x4C00003C
[0xF0009F44] = 0x024665A2

IDX 73 - active descriptor
[0xF0009F48] = 0x4C00004E  - owns BestComm, should transfer
[0xF0009F4C] = 0x0243F05E

IDX 74
[0xF0009F50] = 0x4C00004E
[0xF0009F54] = 0x0243F85E

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