> 2023年2月22日 17:24，Robin Murphy <robin.mur...@arm.com> 写道：
[...]
>
> AFAICS, all you should actually need is a single self-contained addition
> here, something like:
>
> + /*
> + * DT-based MIPS doesn't use OF_DMA_DEFAULT_COHERENT, but
> + * might override the system-wide default at runtime.
> + */
> +#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
> + defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
> + defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
> + is_coherent = dma_default_coherent;
> +#endif
That makes more sense, thanks.
I’ll append CONFIG_MIPS as a condition here as well because it may break RISC-V
whose dma_default_coherent
is not set to true from very beginning.
>
>> node = of_node_get(np);
>>
>
> Then *after* that's fixed, we can do a more comprehensive refactoring to
> merge the two mechanisms properly. FWIW I think I'd prefer an approach closer
> to the first one, where config options control the initial value of
> dma_default_coherent rather than architectures having to override it
> unconditionally (and TBH I'd also like to have a generic config symbol for
> whether an arch supports per-device coherency or not).
Ok I’ll try to revert to the initial way.
Is there any reason that an arch can’t support per-device coherency?
Thanks
- Jiaxun
>
> Thanks,
> Robin.
