> 2023年2月22日 12:55，Robin Murphy <robin.mur...@arm.com> 写道：
>
> On 2023-02-21 19:55, Jiaxun Yang wrote:
>>> 2023年2月21日 19:46，Robin Murphy <robin.mur...@arm.com> 写道：
>>>
>>> On 2023-02-21 18:15, Jiaxun Yang wrote:
>>>>> 2023年2月21日 17:54，Christoph Hellwig <h...@lst.de> 写道：
>>>>>
>>>>> Can you explain the motivation here? Also why riscv patches are at
>>>>> the end of a mips fіxes series?
>>>> Ah sorry for any confusion.
>>>> So the main purpose of this patch is to fix MIPS’s broken per-device
>>>> coherency.
>>>> To be more precise, we want to be able to control the default coherency
>>>> for all devices probed from
>>>> devicetree in early boot code.
>>>
>>> Including the patch which actually does that would be helpful. As it is,
>>> patches 4-7 here just appear to be moving an option around for no practical
>>> effect.
>> Well the affect is default coherency of devicetree probed devices are now
>> following dma_default_coherent
>> instead of a static Kconfig option. For MIPS platform, dma_default_coherent
>> will be determined by boot code.
>
> "Will be" is the issue I'm getting at. We can't review some future promise of
> a patch, we can only review actual patches. And it's hard to meaningfully
> review preparatory patches for some change without the full context of that
> change.
Actually this already present in current MIPS platform code.
arch/mips/mti-malta is setting dma_default_coherent on boot, and it’s
devicetree does not explicitly specify coherency.
Thanks
- Jiaxun
>
> Thanks,
> Robin.
