linux-kernel - Re: [PATCH 2/3] ARM: OMAP: hwmod: revise deassert sequence

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Date:	Fri, 3 Aug 2012 10:54:47 +0530
From:	Vaibhav Hiremath <hvaibhav@...com>
To:	Omar Ramirez Luna <omar.luna@...aro.org>
CC:	Paul Walmsley <paul@...an.com>, Benoit Cousson <b-cousson@...com>,
	Tony Lindgren <tony@...mide.com>,
	Russell King <linux@....linux.org.uk>,
	Kevin Hilman <khilman@...com>,
	Ohad Ben-Cohen <ohad@...ery.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	<linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] ARM: OMAP: hwmod: revise deassert sequence



On 8/3/2012 3:50 AM, Omar Ramirez Luna wrote:
> Hi.
> 
> On 2 August 2012 02:52, Paul Walmsley <paul@...an.com> wrote:
>> On Mon, 16 Jul 2012, Omar Ramirez Luna wrote:
>>
>>> For a reset sequence to complete cleanly, a module needs its
>>> associated clocks to be enabled, otherwise the timeout check
>>> in prcm code can print a false failure (failed to hardreset)
>>> that occurs because the clocks aren't powered ON and the status
>>> bit checked can't transition without them.
>>>
>>> Signed-off-by: Omar Ramirez Luna <omar.luna@...aro.org>
>>
>> Is enabling the clocks sufficient?
> 
> During my testing it seemed enough, besides it looks clk framework is
> doing the same as _omap4_enable_module.
> 
>> Or do we also need to enable the
>> IP block, e.g. by calling
>>
>>         if (soc_ops.enable_module)
>>                 soc_ops.enable_module(oh);
>>
>> as we do on OMAP4+ in _enable() ?
> 
> Basically this is a call to _omap4_enable_module, and the latter will
> "Enable the modulemode inside CLKCTRL".
> 
> However, _enable_clocks path which ends calling omap2_dflt_clk_enable
> does the same thing with its clk->enable_reg field.
> 
> So in _enable:
> 
>         _enable_clocks(oh);
>         if (soc_ops.enable_module)
>                 soc_ops.enable_module(oh);
> 
> The enable_module part seems redundant to me, since the module should
> be already enabled by the first call to _enable_clocks.
> 

Yes they do same thing, I believe the plan is to get rid of all clock
leaf-nodes in the near future, and let hwmod handle module
enable/disable part.

Thanks,
Vaibhav

> Regards,
> 
> Omar
> --
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