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Old 05-21-2010, 07:10 AM   #1
Registered: Aug 2005
Distribution: Arch Linux
Posts: 291

Rep: Reputation: 48
Tracking BCM43xx DMA problem on

I have a laptop with the broadcom BCM4312 wireless device. After some recent troubles with wireless not working out-of-the-box for this device, i had to run Linux on a relatively older kernel... and now when there are any software updates, i am have to be very careful.

Though information on the internet says that BCM43XX devices should work with PIO mode enabled, i could never get it working. Now that wireless is working on the older kernel, i couldn't care less about the PIO mode.

Nevertheless i am tracking the changelog that appear on new kernel updates on I though it would be helpful for others who are struggling with BCM4312/BCM43XX.

Please contribute to this thread if you spot something flowery about BCM43XX drivers' DMA mode on the changelog.

commit b02914af4d7020828ce921a572589dd793517c09
Author: Larry Finger <>
Date:   Thu Dec 10 17:35:01 2009 -0600

    b43: Allow PIO mode to be selected at module load
    If userencounter the "Fatal DMA Problem" with a BCM43XX device, and
    still wish to use b43 as the driver, their only option is to rebuild
    the kernel with CONFIG_B43_FORCE_PIO. This patch removes this option and
    allows PIO mode to be selected with a load-time parameter for the module.
    Note that the configuration variable CONFIG_B43_PIO is also removed.
    Once the DMA problem with the BCM4312 devices is solved, this patch will
    likely be reverted.
    Signed-off-by: Larry Finger <>
    Tested-by: John Daiker <>
    Signed-off-by: John W. Linville <>
Old 09-10-2010, 01:11 AM   #2
Registered: Aug 2005
Distribution: Arch Linux
Posts: 291

Original Poster
Rep: Reputation: 48


Hope that applies to 4312 also...

Last edited by logicalfuzz; 09-10-2010 at 01:15 AM.



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