linux-kernel - Re: [PATCH 1/3] ARM: OMAP: hwmod: partially un-reset hwmods might not be properly enabled

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Message-ID: <CALLhW=44R0H-3k5qU=Uckf9UjzP2=xLFYXJt8Nce7VoKFpX_dQ@mail.gmail.com>
Date:	Mon, 20 Aug 2012 20:13:47 -0500
From:	Omar Ramirez Luna <omar.luna@...aro.org>
To:	Benoit Cousson <b-cousson@...com>
Cc:	Paul Walmsley <paul@...an.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 1/3] ARM: OMAP: hwmod: partially un-reset hwmods might not
 be properly enabled

Hi Benoit,

On 20 August 2012 09:49, Benoit Cousson <b-cousson@...com> wrote:
> On 07/16/2012 09:21 PM, Omar Ramirez Luna wrote:
>> Some IP blocks might not be using/controlling more than one
>> reset line, this check loosens the restriction to fully use
>> hwmod framework for those drivers.
>>
>> E.g.: ipu has reset lines: mmu_cache, cpu0 and cpu1.
>> - cpu1 might not be used and hence (with previous check)
>>   won't be fully enabled by hwmod code.
>
> You mean that you might have some case where you need to enable the
> mmu_cache and cpu0 and thus deassert only the mmu/cpu0 while keeping the
> cpu1 under reset?
>
> So the any_hardreset is indeed not appropriate in that case.
>
> In fact, since the hardreset cannot be handled at all by the hwmod fmwk,
> I'm even wondering if we should take care of checking the state at all.
> But as Paul stated, if was done due to the lack of understanding about
> the diver usage, so maybe things will become clearer once we will have
> that code available.
>
> So I guess that checking for all the lines for the hardreset state is
> anyway already a first step toward a good understanding of the reset
> need for the remote processors.
>
> The patch looks fine to me considering that we do not have a lot of
> information about the usage :-(
>
> Maybe you could add more information in the changelog to explain the way
> you are going to use the reset API.

I'll add an updated description with more information.

Thanks for the comments,

Omar
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