Coherent bus_dma for ARMv7

[Marcin Wojtas]

Hi Adrian,

Frankly we are not such experts in armv6 bus_dma, which looks more
complicated than one in arm64, so we thought it's much safer no to mix
the two solutions and leave for the user a single switch to decide,
which one to pick. Afaik Andrew Turner did the oposite for arm64
(implement not coherent solution on top of coherent bus_dma), however
I'm not sure if it's possible here in an easy way - there's also
pretty significant risk of regression for all platforms. Please let me
know your opinion. Do you think some sort of update of armv6 is
doable?

Marcin

2017-04-02 2:00 GMT+02:00 Adrian Chadd <adrian.chadd at gmail.com>:
> hiya,
>
> so why's this need to be different? can't it somehow be merged with
> the existing busdma code?
>
>
>
> -adrian
>
>
> On 31 March 2017 at 07:05, Marcin Wojtas <mw at semihalf.com> wrote:
>> Patch with the coherent bus_dma support attached.
>>
>> Marcin
>>
>> 2017-03-31 16:01 GMT+02:00 Marcin Wojtas <mw at semihalf.com>:
>>> Hi,
>>>
>>> In current FreeBSD-HEAD ARMv7 platforms, which support hardware IO
>>> cache coherency cannot make use of this feature. In our project we
>>> implemented coherent variant bus_dma, which is basing on x86 and arm64
>>> approach. Using of above solution is not obligatory and depends on
>>> setting newly added option for that purpose.
>>>
>>> Needless to say, our platform (Marvell Armada 38x) IO performance
>>> boosted after switching to it. Do you wish to enable such option in
>>> HEAD?
>>>
>>> Regards,
>>> Marcin
>>
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