Re: brcmsmac hangs machine if loaded after busmastering disabled

["Arend van Spriel" <arend@broadcom.com>]

On 04/18/2012 02:34 PM, Matthew Garrett wrote:
> On Wed, Apr 18, 2012 at 01:32:39PM +0200, Arend van Spriel wrote:
>> I discussed this with hardware designer and here is his quote "You
>> would need to disable the DMA engines before disable PCIe master
>> mode. If you didn't do that, and the DMA engines were active, the
>> MAC would almost certainly hang."
>>
>> So disabling the master mode solved your memory corruption, but the
>> chip will hang. The DMA engines mentioned are the on-chip engines.
>> As you indicated you can only use common PCI operations so I do not
>> expect disabling BAR decoding will solve the hang in the chip.
>
> Yeah, I can get away with putting generic PCI operations in the
> bootloader, but a specific Broadcom driver is probably going a bit
> far...
>
>> Only as an experiment you could try to reset the device toggling the
>> pci power state.
>
> Should putting the PCI device in D3 be sufficient for this, or would I
> also need to touch any state in the 802.11 core?
>

I am not sure, but D3 is a good guess. It is all a workaround as the 
real fix should be in Apple's UEFI implementation. I think it is 
unlikely we can make them do that although we probably supplied them the 
wireless part.

Gr. AvS