linux-kernel - Re: [PATCH 05/10] ARM: OMAP2+: Disable GPIO softreset for dm81xx

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Message-ID: <20151202005430.GY23396@atomide.com>
Date:	Tue, 1 Dec 2015 16:54:30 -0800
From:	Tony Lindgren <tony@...mide.com>
To:	Matthijs van Duin <matthijsvanduin@...il.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Brian Hutchinson <b.hutchman@...il.com>,
	Delio Brignoli <dbrignoli@...ioscience.com>,
	Neil Armstrong <narmstrong@...libre.com>,
	Philipp Rosenberger <ilu@...utronix.de>,
	Paul Walmsley <paul@...an.com>
Subject: Re: [PATCH 05/10] ARM: OMAP2+: Disable GPIO softreset for dm81xx

* Tony Lindgren <tony@...mide.com> [151201 16:42]:
> * Matthijs van Duin <matthijsvanduin@...il.com> [151201 16:11]:
> > On 2 December 2015 at 00:38, Tony Lindgren <tony@...mide.com> wrote:
> > > Looks like GPIO softreset status bit on both dm8168 and dm8148
> > > is broken and only goes high initially. After writing to sysc
> > > softreset bit, the resetdone bit never goes high again.
> > 
> > The resetdone bit works fine, but it needs all clocks active to come
> > up. You're neglecting to enable the debounce clock to the GPIO module:
> > 
> > > # mw.l 0x4818155c 0x2
> > 
> > That should write 0x102 instead.
> 
> It seems to work only once based on what I've seen :) If you try it
> after it's powered it never works. Could be I'm doing something wrong
> of course..
> 
> > You can disable the debounce clock after resetting the module if you
> > don't need it, though I doubt there's any significant power savings
> > there. (More likely it exists as a separate bit to allow it to stay
> > enabled even if the module isn't, for wakeup on debounced inputs.)
> 
> Hmm I tried setting HWMOD_CONTROL_OPT_CLKS_IN_RESET flag like we
> have for many SoCs to enable also sysclk18_ck but no luck. I can
> recheck that.

You're right with 0x102 it works, need to debug further.

Thanks,

Tony
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