setpci is no changing values

[<joerg.beyer@email.de>]

Hi,

I have some trouble with a laptop's NIC (it's a 8139C realtek chip, I use the rtl8139 module). With
a lot help I think the problem is tracked down to a problem with the PCI bus bandwidth.

The diagnosis  is as follows:

after a scp of 17 MBytes in 9 seconds /proc/net/dev gave this:

Inter-| Receive | Transmit
face |bytes packets errs drop fifo frame compressed multicast|bytes packets errs drop fifo colls carrier compressed
lo: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
dummy0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
eth0:18454280 12218 1257 1257 1257 0 0 0 868920 12225 0 0 0 7 0 0


and there are the errors as reported by ifconfig:

eth0 Link encap:Ethernet HWaddr 00:07:CA:00:AC:A3
inet addr:10.0.0.30 Bcast:10.255.255.255 Mask:255.0.0.0
UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
RX packets:12215 errors:1257 dropped:1257 overruns:1257 frame:0
TX packets:12220 errors:0 dropped:0 overruns:0 carrier:0
collisions:7 txqueuelen:100
RX bytes:18454074 (17.5 Mb) TX bytes:868093 (847.7 Kb)
Interrupt:10 Base address:0x1c00

this is from /var/log/messages:

Aug 31 20:51:14 wally last message repeated 3 times
Aug 31 20:51:14 wally kernel: eth0: Abnormal interrupt, status 00000040.
Aug 31 20:51:14 wally last message repeated 2 times
Aug 31 20:51:14 wally kernel: eth0: Abnormal interrupt, status 00000041.
Aug 31 20:51:14 wally last message repeated 3 times
Aug 31 20:51:14 wally kernel: eth0: Abnormal interrupt, status 00000040.
Aug 31 20:51:14 wally last message repeated 7 times
Aug 31 20:51:14 wally kernel: eth0: Abnormal interrupt, status 00000041.
Aug 31 20:51:14 wally kernel: eth0: Abnormal interrupt, status 00000040.
Aug 31 20:51:14 wally kernel: eth0: Abnormal interrupt, status 00000040.

I was suggested to increase the minimum grant to 64, so I did the following:

joerg@notebook> setpci -v -s 0:9.0.0 min_gnt=40
00:09.0:3e 40

BUT when I compared the output of lspci -vvvxxx -s 0:9.0 before and after
the setpci command, then I found no difference. Is this the expected behaviour?
I strace setpci and I found that the 62. Byte (== 0x3e) was written on
/proc/bus/pci/00/09.0

Any suggestions how to change the minimum grant?
Any other suggestions how to get rid of the NIC errors?

I used differne 2.4 kernels with the latest acpi (otherwise I dont get
a IRQ for the nic), up  to 20-pre5 with roughly the same results.

    TIA
    Joerg

ps: since I am not on the list, it would be nice to cc be - but I also read
lkml on the web.