Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Jim Quinlan <james.quinlan@broadcom.com>
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Subject: Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets
Date: Thu, 4 Jun 2020 18:05:35 +0300	[thread overview]
Message-ID: <20200604150535.GB2428291@smile.fi.intel.com> (raw)
In-Reply-To: <CA+-6iNz1-1wOurKoOJzhbVL0_YP7dbmp0wy1GWkLW_61yhRXyA@mail.gmail.com>

On Thu, Jun 04, 2020 at 10:35:12AM -0400, Jim Quinlan wrote:
> On Thu, Jun 4, 2020 at 9:53 AM Nicolas Saenz Julienne
> <nsaenzjulienne@suse.de> wrote:
> > On Wed, 2020-06-03 at 15:20 -0400, Jim Quinlan wrote:

...

> > > +     phys = virt_to_phys(ret);
> > > +     pfn =  phys >> PAGE_SHIFT;
> >
> > nit: not sure it really pays off to have a pfn variable here.
> Did it for readability; the compiler's optimization should take care
> of any extra variables.  But I can switch if you insist.

One side note: please, try to get familiar with existing helpers in the kernel.
For example, above line is like

	pfn = PFN_DOWN(phys);

...

> > > +     if (!WARN_ON(!dev) && dev->dma_pfn_offset_map)

> > > +             *dma_handle -= PFN_PHYS(
> > > +                     dma_pfn_offset_from_phys_addr(dev, phys));

Don't do such indentation, esp. we have now 100! :-)

-- 
With Best Regards,
Andy Shevchenko

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