Re: [PATCH v4 3/7] of/address: Introduce of_dma_get_max_cpu_address()

[Nicolas Saenz Julienne]

On Thu, 2020-10-22 at 14:23 +0200, Ard Biesheuvel wrote:
> > +/**
> > + * of_dma_get_max_cpu_address - Gets highest CPU address suitable for DMA
> > + * @np: The node to start searching from or NULL to start from the root
> > + *
> > + * Gets the highest CPU physical address that is addressable by all DMA masters
> > + * in the sub-tree pointed by np, or the whole tree if NULL is passed. If no
> > + * DMA constrained device is found, it returns PHYS_ADDR_MAX.
> > + */
> > +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;
> > +       struct of_range range;
> > +       const __be32 *ranges;
> > +       u64 cpu_end = 0;
> > +       int len;
> > +
> > +       if (!np)
> > +               np = of_root;
> > +
> > +       ranges = of_get_property(np, "dma-ranges", &len);
> > +       if (ranges && len) {
> > +               of_dma_range_parser_init(&parser, np);
> > +               for_each_of_range(&parser, &range)
> > +                       if (range.cpu_addr + range.size > cpu_end)
> > +                               cpu_end = range.cpu_addr + range.size;
> 
> 
> Shouldn't this be 'range.cpu_addr + range.size - 1' ?

Yes, I agree. In that case arm64's counterpart should be:

	zone_dma_bits = max(32U, fls64(of_dma_get_max_cpu_address(NULL)));

I'll update it.

Regards,
Nicolas

Attachment: signature.asc
Description: This is a digitally signed message part