From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
Subject: Re: [PATCH v2 2/9] mailbox: Add NVIDIA Tegra XUSB mailbox driver
Date: Tue, 26 Aug 2014 09:43:50 +0200
Message-ID: <3804028.YQzQ4uAVsf@wuerfel>
References: <1408381705-3623-1-git-send-email-abrestic@chromium.org> <53FB8820.4010202@wwwdotorg.org> <20140826065729.GC15573@ulmo>
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To: Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>, Andrew Bresticker <abrestic-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>, Ian Campbell <ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>, Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>, Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>, Jassi Brar <jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Greg Kroah-Hartman <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>, Mathias Nyman <mathias.nyman-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Alan Stern <stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org>, Kishon Vijay Abraham I <kishon-l0cyMroinI0@public.gmane.org>, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
List-Id: devicetree@vger.kernel.org

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.

	Arnd
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