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Date:	Sun, 16 Nov 2014 01:05:26 +0100
Subject: re: bug? mac 00:00:00:00:00:00 with natsemi DP83815 after driver

forwarding to lkml, as no response on netdev list so far.
maybe someone has a clue how to properly fix this timing issue.  the remaining question is about how to correctly replace readl() with inl() to make it compile cleanly or how eeprom_delay() is being done correctly.  inl() seems to be slower to complete which seems to make the driver work, but it seems it needs an I/O port as param but not an memory-adress. 

sorry, i`m not good at programming, but now as the problem is "basically" fixed there are just some tiny bits missing for a proper fix. i´m unsure if typecasting ee_addr is the right thing to do (i think it`s not) and if a patch with such typecast would have any chance for being accepted.

as i`m doing a little project with this older devices, i have come across this issue again and had some fun to dig deeper into it.

it`s a little bit academic, as i can do ifconfig eth0 hw ether..... as a workaround, but it sucks to hack that into startup scripts and i also have seen udev not playing nicely with it.

apparently the problem is being caused by a timing issue in the natsemi driver.

i added some debug printk`s in natsemi.c -> eeprom_read() after each occurrence of eeprom_delay(ee_addr); , and the problem went away. 

there is a hint about timing sensitivity in the code:

/* Delay between EEPROM clock transitions.
   No extra delay is needed with 33Mhz PCI, but future 66Mhz access may need
   a delay.  Note that pre-2.0.34 kernels had a cache-alignment bug that
   made udelay() unreliable.
   The old method of using an ISA access as a delay, __SLOW_DOWN_IO__, is

looking at the source of natsemi-diag.c made me wonder why that utility is using 

#define eeprom_delay(ee_addr)   inl(ee_addr)

instead of 

#define eeprom_delay(ee_addr)   readl(ee_addr)

and apparently, that also fixes the problem (but gives a compile warning):

drivers/net/ethernet/natsemi/natsemi.c: In function âeeprom_readâ:
drivers/net/ethernet/natsemi/natsemi.c:1019:3: warning: passing argument 1 of âinlâ makes integer from pointer without a cast [enabled by default]
In file included from include/linux/io.h:22:0,
                 from include/linux/pci.h:54,
                 from drivers/net/ethernet/natsemi/natsemi.c:38:

looking at a more recent version of natsemi-diag.c ,  i even found this one:

/* Delay between EEPROM clock transitions.
   This flushes the write buffer to prevent quick double-writes.
#define eeprom_delay(ee_addr)	inl(ee_addr); inl(ee_addr)

The question is how to make a proper fix, as i don`t know what to pass to inl() , as it seems it should not get an mmapped adress but an i/o port instead !?

"The  in*() functions return data read from the specified I/O port"

"The read*() functions read data from device memory previously mapped by map_memory()"


ps: CC driver maintainer from Kernel Maintainers file.

Roland Kletzing | 17 Dec 13:38 2012
bug? mac 00:00:00:00:00:00 with natsemi DP83815 after driver load

i recently played with my older evo t20/wyse 3235le thin clients and flashed
a linux kernel into those, apparently there seems an issue with the natsemi

after driver load (natsemi.ko) eth0 has no valid mac adress, dmesg and
ifconfig shows just zero`s: 00:00:00:00:00:00.

despite that , the nic is working fine for me (in this test setup i set the
mac manually: ifconfig eth0 hw ether de:ad:be:ef:be:ef )

apparently, the driver fails to read the proper mac from the eeprom, as
"natsemi-diag -ee" (from nictools-pci in debian squeeze) shows, that there
is a valid "Ethernet MAC Station Address" stored inside the eeprom. (see

looks like a driver bug !?
does anybody have a clue what`s going wrong here?



00:00.0 Host bridge: Cyrix Corporation PCI Master
00:0f.0 Ethernet controller: National Semiconductor Corporation DP83815
(MacPhyter) Ethernet Controller
00:12.0 ISA bridge: Cyrix Corporation 5530 Legacy [Kahlua] (rev 30)
00:12.1 Bridge: Cyrix Corporation 5530 SMI [Kahlua]
00:12.2 IDE interface: Cyrix Corporation 5530 IDE [Kahlua]
00:12.3 Multimedia audio controller: Cyrix Corporation 5530 Audio [Kahlua]
00:12.4 VGA compatible controller: Cyrix Corporation 5530 Video [Kahlua]
00:13.0 USB Controller: Compaq Computer Corporation ZFMicro Chipset USB (rev

#dmesg |egrep "natsemi|eth"
natsemi dp8381x driver, version 2.1, Sept 11, 2006
natsemi 0000:00:0f.0: setting latency timer to 64
natsemi eth0: NatSemi DP8381[56] at 0x4010000 (0000:00:0f.0),
00:00:00:00:00:00, IRQ 10, port TP.
eth0: DSPCFG accepted after 0 usec.
eth0: link up.
eth0: Setting full-duplex based on negotiated link capability.

#natsemi-diag -aa
natsemi-diag.c:v2.08 2/28/2005 Donald Becker (becker <at>
Index #1: Found a NatSemi DP83815 adapter at 0xf800.
 Natsemi 83815 series with station address de:ad:be:ef:be:ef
 Transceiver setting Autonegotation advertise 10/100 Mbps half and full
 This device appears to be active, so some registers will not be read.
 To see all register values use the '-f' flag.
NatSemi DP83815 chip registers at 0xf800
 0x000: 00000004 e805e000 00000002 00000000 ******** 00f1cd65 00000001
 0x020: 03abd200 d0f01002 00000000 00000000 03abd000 18700010 00000000
 0x040: ******** 00200000 00000004 0000efbe ffff000b 30303030 00000403
 0x060: ******** ******** ******** ******** ******** ******** ********
 0x080: 00003100 0000786d 00002000 00005c21 000005e1 000045e1 00000005
 0x0A0: ******** ******** ******** ******** ******** ******** ********
 0x0C0: 00000615 00000002 00000000 00000000 00000000 00000000 00000100
 0x0E0: 00000000 000000bf 00000804 00008200 00000000 00000000 00000000
  Interrupt sources are pending (00000200).
   Tx queue emptied indication.
  Receive mode is 0xc8200000: Normal unicast and hashed multicast.
  Rx filter contents:   adde efbe efbe 0000 0000 0000 0000 0000

#natsemi-diag -ee
natsemi-diag.c:v2.08 2/28/2005 Donald Becker (becker <at>
Index #1: Found a NatSemi DP83815 adapter at 0xf800.
 Natsemi 83815 series with station address de:ad:be:ef:be:ef
 Transceiver setting Autonegotation advertise 10/100 Mbps half and full
 EEPROM address length 6, 64 words.
EEPROM contents (64 words):
0x00:  100b 0020 0b34 41fb 0000 0000 0000 4000
0x08:  0d32 dff4 1905 aa48 0000 0000 129c 4c4c
0x10:  ca52 2ccc 0cb2 9c6c 0c6c 8c0c 2020 6080
0x18:  0800 0000 0000 0000 0000 0000 0000 0000
0x20:  0000 0000 0000 0000 0000 0000 0000 0000
0x28:  0000 0000 0000 0000 0000 0000 0000 0000
0x30:  0000 0000 0000 0000 0000 0000 0000 0000
0x38:  0000 0000 0000 0000 0000 0000 0000 e418
Decoded EEPROM contents:
  PCI Subsystem IDs -- Vendor 0x100b, Device 0x0020.
  PCI timer settings -- minimum grant 11, maximum latency 52.
  Ethernet MAC Station Address 00:80:64:1a:e8:bf.
  Wake-On-LAN password 00:00:00:00:00:00.
  Transceiver setting 0x--f-: advertise 10/100 Mbps half and full duplex.
   Flow control enabled.
  EEPROM active region checksum read as aa48, vs aa48 calculated value.
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