Re: [PATCH v3 3/8] of/address: Introduce of_dma_get_max_cpu_address()

Rob Herring
2020-10-16T13:20:05Z

On Thu, Oct 15, 2020 at 12:42 AM Christoph Hellwig <hch@lst.de> wrote:
>
> > +phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np)
> > +{
> > + phys_addr_t max_cpu_addr = PHYS_ADDR_MAX;
> > + struct of_range_parser parser;
> > + phys_addr_t subtree_max_addr;
> > + struct device_node *child;
> > + phys_addr_t cpu_end = 0;
> > + struct of_range range;
> > + const __be32 *ranges;
> > + int len;
> > +
> > + if (!np)
> > + np = of_root;
>
> Requiring of_root to be passed explicitly would seem more natural
> to me than the magic NULL argument. There doesn't seem to be any
> precedent for that kind of calling convention either.

I prefer that of_root is not more widely exposed and NULL regularly
means 'the whole tree'.

Rob