Re: [PATCH 0/7] MIPS DMA coherence fixes

[Robin Murphy]

On 2023-02-21 19:55, Jiaxun Yang wrote:
> > 2023年2月21日 19:46，Robin Murphy <robin.murphy@xxxxxxx> 写道：
> >
> > On 2023-02-21 18:15, Jiaxun Yang wrote:
> > > > 2023年2月21日 17:54，Christoph Hellwig <hch@xxxxxx> 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.

Thanks,
Robin.