kern/144724: if_bwn does not pass traffic when in PIO mode

Joe Marcus Clarke marcus at
Sun Mar 14 00:50:02 UTC 2010

>Number:         144724
>Category:       kern
>Synopsis:       if_bwn does not pass traffic when in PIO mode
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Mar 14 00:50:01 UTC 2010
>Originator:     Joe Marcus Clarke
>Release:        9-CURRENT
FreeBSD 9.0-CURRENT #105: Wed Mar  3 23:37:36 EST 2010
    marcus at i386
When putting the bwn driver into PIO mode in my Dell Vostro 2510, the card associates, but does not pass traffic.

Weongyo Jeong has been looking into this, and asked me to file a PR.  Here is the link to the dmesg output when running with a debug patch.  This output is when the driver is in (working) DMA mode:

This is when the driver is put into PIO mode:

Note: running in DMA mode is spotty for me.  Sometimes it works, but other times, the driver enters a fatal DMA error loop, and the laptop must be rebooted (power cycled) to recover.

My card is an LP PHY card:

siba_bwn0 at pci0:6:0:0:   class=0x028000 card=0x000b1028 chip=0x431514e4 rev=0x01 hdr=0x00
    vendor     = 'Broadcom Corporation'
    device     = 'Broadcom Wireless b/g (BCM4315/BCM22062000)'
    class      = network
Set hw.bwn.usedma="0" in loader.conf, then reboot.


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