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

On 01/29/2015 11:05 AM, Russell King - ARM Linux wrote:

On Thu, Jan 29, 2015 at 10:49:34AM -0500, Peter Hurley wrote:

quoted

Hi Varka,

On 01/29/2015 10:26 AM, Varka Bhadram wrote:

quoted

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.

Maybe the purpose would be better served by wrapping the idiom in a single
function.

Regards,
Peter Hurley
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