[PATCH RESEND v10 07/11] device-mapping: Introduce DMA range map, supplanting dma_pfn_offset

[Andy Shevchenko]

On Thu, Aug 20, 2020 at 09:37:12AM -0400, Jim Quinlan wrote:
> On Tue, Aug 18, 2020 at 4:14 AM Andy Shevchenko
> <andriy.shevchenko at linux.intel.com> wrote:
> > On Mon, Aug 17, 2020 at 05:53:09PM -0400, Jim Quinlan wrote:

...

> > > +static inline u64 dma_offset_from_dma_addr(struct device *dev, dma_addr_t dma_addr)
> > > +{
> > > +     const struct bus_dma_region *m = dev->dma_range_map;
> > > +
> > > +     if (!m)
> > > +             return 0;
> > > +     for (; m->size; m++)
> > > +             if (dma_addr >= m->dma_start && dma_addr - m->dma_start < m->size)
> > > +                     return m->offset;
> > > +     return 0;
> > > +}
> > > +
> > > +static inline u64 dma_offset_from_phys_addr(struct device *dev, phys_addr_t paddr)
> > > +{
> > > +     const struct bus_dma_region *m = dev->dma_range_map;
> > > +
> > > +     if (!m)
> > > +             return 0;
> > > +     for (; m->size; m++)
> > > +             if (paddr >= m->cpu_start && paddr - m->cpu_start < m->size)
> > > +                     return m->offset;
> > > +     return 0;
> > > +}
> >
> > Perhaps for these the form with one return 0 is easier to read
> >
> >         if (m) {
> >                 for (; m->size; m++)
> >                         if (paddr >= m->cpu_start && paddr - m->cpu_start < m->size)
> >                                 return m->offset;
> >         }
> >         return 0;
> >
> > ?
> I see what you are saying but I don't think there is enough difference
> between the two to justify changing it.

The difference is that you have return 0 / non-0 cases one each. I think it's
slightly easier to read and understand, but it's up to you.

-- 
With Best Regards,
Andy Shevchenko