Re: [PATCH v2 2/9] mailbox: Add NVIDIA Tegra XUSB mailbox driver
From: Arnd Bergmann
Date: Tue Aug 26 2014 - 03:46:10 EST
On Tuesday 26 August 2014 08:57:31 Thierry Reding wrote:
> On Mon, Aug 25, 2014 at 01:01:52PM -0600, Stephen Warren wrote:
> > On 08/18/2014 11:08 AM, Andrew Bresticker wrote:
> > >+static int tegra_xusb_mbox_probe(struct platform_device *pdev)
> > >+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > >+ if (!res)
> > >+ return -ENODEV;
> > Should devm_request_mem_region() be called here to claim the region?
> > >+ mbox->regs = devm_ioremap_nocache(&pdev->dev, res->start,
> > >+ resource_size(res));
> > >+ if (!mbox->regs)
> > >+ return -ENOMEM;
> > Is _nocache required? I don't see other drivers using it. I assume there's
> > nothing special about the mbox registers.
> Most drivers should be using devm_ioremap_resource() which will use the
> _nocache variant of devm_ioremap() when appropriate. Usually the region
> will not be marked cacheable (IORESOURCE_CACHEABLE) and therefore be
> remapped uncached.
Note that ioremap() and ioremap_nocache() are the same. We really shouldn't
ever call ioremap_nocache().
devm_ioremap_resource() and pci_iomap() checking for IORESOURCE_CACHEABLE is
rather silly, since it doesn't call ioremap_cache() in that case.
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