linux-kernel - Re: [PATCH 1/3] ARM: imx: Add common imx cpuidle init functionality.

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Message-ID: <20120417141309.GH11786@async.com.br>
Date:	Tue, 17 Apr 2012 11:13:09 -0300
From:	Christian Robottom Reis <kiko@...aro.org>
To:	Rob Lee <rob.lee@...aro.org>
Cc:	Sascha Hauer <s.hauer@...gutronix.de>, linaro-dev@...ts.linaro.org,
	patches@...aro.org, linux-kernel@...r.kernel.org,
	kernel@...gutronix.de, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/3] ARM: imx: Add common imx cpuidle init functionality.

On Tue, Apr 17, 2012 at 08:54:03AM -0500, Rob Lee wrote:
> >> +void __init imx_cpuidle_set_driver(struct cpuidle_driver *p)
> >> +{
> >> +     drv = p;
> >> +}
> >
> > You like it complicated, eh? Why do you introduce a function which sets
> > a variable...
> 
> This complication is used to deal with the timing of various levels of
> init calls.  More explanation below.

Regardless of how you end up solving this, it's probably a good idea
to document the rationale, perhaps cribbing from what you describe
below..

> If I called imx_cpuidle_init directly from imx5 or imx6q init
> routines, it would be getting called before the coreinit_call of core
> cpuidle causing a failure.  There were various other directions to
> take and all seemed less desirable than this one.
> 
> One alternative would be to add a function to return the pointer to
> the cpuidle driver object based on the machine type.  Functionality
> exists to identify imx5 as a machine type but not imx6q, so I couldn't
> use that machine based method without adding that extra code.
> 
> Another alternative would be to add a general platform lateinit_call
> function to each platforms that support cpuidle.

..in a comment; without it, the code indeed looks bizarre.
-- 
Christian Robottom Reis, Engineering VP
Brazil (GMT-3) | [+55] 16 9112 6430 | [+1] 612 216 4935
Linaro.org: Open Source Software for ARM SoCs
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