linux-kernel - Re: AM335x OMAP2 common clock external fixed-clock registration

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Message-ID: <20150415140945.GA30787@deathray>
Date:	Wed, 15 Apr 2015 09:09:45 -0500
From:	Michael Welling <mwelling@...e.org>
To:	Tero Kristo <t-kristo@...com>
Cc:	Mike Turquette <mturquette@...aro.org>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	tony@...mide.com, gregkh@...uxfoundation.org,
	Daniel Mack <daniel@...que.org>
Subject: Re: AM335x OMAP2 common clock external fixed-clock registration

On Wed, Apr 15, 2015 at 09:34:48AM +0300, Tero Kristo wrote:
> On 04/15/2015 12:17 AM, Michael Welling wrote:
> >Greetings,
> >
> >I have developed an AM3354 based SoM and it uses an external SI5351 clock
> >generator to drive the clock inputs for an external duart and I2S audio
> >master clock. With the registration according to the documentation the
> >reference clock is not being detected and hence the clock generator is
> >not working as expect.
> >
> >After trying many different things, I started to look around the mailing
> >lists to find information related to this issue.
> >
> >I came acrossed post that has the exact same issue:
> >https://lkml.org/lkml/2013/2/18/468
> >
> >Seeing as the patch did not land upstream, I am wondering if there is
> >a solution that I am not seeing.
> >
> >I am willing to provide a patch given appropriate guidance.
> 
> Hi Michael,
> 
> The info on the email you referenced is kind of obsolete, TI SoCs
> are calling of_clk_init() during boot now, and thus external clock
> nodes should be registered fine also. Maybe you can provide the
> actual DTS patch you are trying out so we can help better...? Are

See attached patch and console output.

> you seeing any boot time error / warning prints for your new clock?

With the debug messages on you see that the reference clock is not being
detected.

Whilest debugging I found that the of_clk_get is returning an error no matter
which clock I pass it:
http://lxr.free-electrons.com/source/drivers/clk/clk-si5351.c#L1131

> 
> -Tero

View attachment "som-3354.patch" of type "text/x-diff" (14862 bytes)

View attachment "som-3354-com.txt" of type "text/plain" (41364 bytes)