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

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Date:	Thu, 2 Aug 2012 17:20:27 -0500
From:	Omar Ramirez Luna <omar.luna@...aro.org>
To:	Paul Walmsley <paul@...an.com>
Cc:	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

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.

Regards,

Omar
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