of_iomap() and devres questions

of_iomap() and devres questions

[Markus Mayer]

Hi all,

I have a few questions regarding the implementation of the of_iomap() 
function.

As it currently stands, the function parses the device tree for the 
device's address and then simply calls ioremap() with that address and 
the associated size.

The first question that has come up is why of_iomap() doesn't also call 
request_mem_region()? Is there a particular reason for it or has it just 
not yet been implemented?

The second question is regarding the use of devres in of_iomap(). Would 
it make sense for of_iomap() to use devm_ioremap() or, better yet, 
devm_request_and_ioremap() instead of simply calling ioremap()?

Thanks,
-Markus

Re: of_iomap() and devres questions

[Rob Herring]

On 04/02/2013 02:25 PM, Markus Mayer wrote:
> Hi all,
> 
> I have a few questions regarding the implementation of the of_iomap()
> function.
> 
> As it currently stands, the function parses the device tree for the
> device's address and then simply calls ioremap() with that address and
> the associated size.
> 
> The first question that has come up is why of_iomap() doesn't also call
> request_mem_region()? Is there a particular reason for it or has it just
> not yet been implemented?

Don't know. It probably should not and make cause some breakage.

> The second question is regarding the use of devres in of_iomap(). Would
> it make sense for of_iomap() to use devm_ioremap() or, better yet,
> devm_request_and_ioremap() instead of simply calling ioremap()?

You should not be using of_iomap in a driver, but rather the functions
you mention. of_iomap is mainly used in cases where there is no driver
or struct device. Which means devm_* functions would be pointless. Also
there is no way to get from a struct device_node ptr to a struct device ptr.

Rob

> 
> Thanks,
> -Markus
> 
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