[PATCH 1/3] b43: replace DMA translation workarounds with just a one, commented

[Larry Finger]

On 07/20/2011 01:16 AM, Rafał Miłecki wrote:
> W dniu 20 lipca 2011 01:15 użytkownik Michael Büsch<m at bues.ch>  napisał:
>> On Wed, 20 Jul 2011 00:12:20 +0200
>> Rafał Miłecki<zajec5 at gmail.com>  wrote:
>>> +              * be fixed on ssb side, but requires testing with b43,
>>> +              * b43legacy and b44. */
>>
>> No it doesn't. b44 and b43legacy don't use 64bit DMA.
>> Just fix it in ssb, please.
>
> They (drivers) don't, but what if we start giving them routing for
> 64-bit DMA? AFAIU they treat 64-bit DMA as 32-bit one (according to
> specs: "If 64 Bit isn't an option, Silicon Backplane and PCI-E buses
> can use 32 bit DMA.").
>
> Won't they start using 64-bit DMA in the 32-bit way but with 64-bit
> routing bits?

The BCM4311 was the first device that supported 64-bit DMA. I had the first of 
those, and I got to debug the 64-bit stuff that had been written by Michael, but 
there had been no hardware for testing. All earlier devices were restricted to 
32-bit paths.

Larry