[PATCH v10 2/2] tty/serial: Add Spreadtrum sc9836-uart driver support

[Russell King - ARM Linux]

On Thu, Jan 29, 2015 at 10:49:34AM -0500, Peter Hurley wrote:
> Hi Varka,
> 
> On 01/29/2015 10:26 AM, Varka Bhadram wrote:
> > This check is not required. It will be done by devm_ioremap_resource()
> 
> I disagree. devm_ioremap_resource() interprets the NULL resource as
> a bad parameter and returns -EINVAL which is then forwarded as the
> return value from the probe.
> 
> -ENODEV is the correct return value from the probe if the expected
> resource is not available (either because it doesn't exist or was already
> claimed by another driver).

(Adding Thierry as the author of this function.)

I believe devm_ioremap_resource() was explicitly designed to remove such
error handling from drivers, and to give drivers a unified error response
to such things as missing resources.

See the comments for this function in lib/devres.c.

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