Subject: [RFC/NOT FOR MERGING 2/3] serial: omap: remove hwmod dependency

From: [email-masked] (Santosh Shilimkar)
Date: Sat, 16 Feb 2013 11:01:00 +0530

On Friday 15 February 2013 10:00 PM, Tony Lindgren wrote:
> * Santosh Shilimkar <[email-masked]> [130215 05:34]:
>> On Friday 15 February 2013 06:57 PM, Russell King - ARM Linux wrote:
>>> On Fri, Feb 15, 2013 at 06:56:47PM +0530, Santosh Shilimkar wrote:
>>>> Whats your view on use of arch_ioremap_caller() hook ? This can allow
>>>> us to avoid the dual ioremap() issue discussed here if the hook
>>>> maintains the list of mapped ios.
>>>>
>>>> I was even thinking of having such intelligence within the core
>>>> ioremap code but thought that might be too invasive.
>>>
>>> Why do you even need it?  There's no problem with ioremapping the same
>>> space multiple times (you end up with multiple mappings but that
>>> shouldn't be a problem, except for the additional space used.)
>>>
>> It just waste of iospace and Tony insisted to have just single ioremap()
>> hence all this discussion
>
> The main goal is to avoid duplicating data both in hwmod and DT.
> That's pretty much solved as we can have the driver probe populate
> the common data for hwmod from DT as Santosh has already demonstrated.
>
Right.

> Then we also want the driver specific idle and reset code to be done
> in the drivers rather than in hwmod and glue it together with hwmod
> using runtime PM. The biggest issue there is how do we reset and idle
> some piece of hardware for PM purposes when there's no driver loaded.
>
Driver idle functions is getting sorted out. There is no need for driver
to fiddle around it since PM runtime back-end can take care of of it.
One attempt to clean that is here [1]

For the reset, we need to have a generic runtime hook as discussed and
that should take care of reset as well. That way driver just calls
generic

> For the duplicate ioremapping, I don't think there's any need to
> do it if we get things right.
>
Good to know. So overall, I think we do have a way to move forward
and get right things done.

Regards,
Santosh

[1] http://www.mail-archive.com/linux-omap at vger.kernel.org/msg85177.html