linux-kernel - Re: [PATCH 7/9] pwm i.MX: fix clock lookup

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Message-ID: <20120906184256.GJ26594@pengutronix.de>
Date:	Thu, 6 Sep 2012 20:42:56 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Benoît Thébaudeau 
	<benoit.thebaudeau@...ansee.com>
Cc:	HACHIMI Samir <shachimi@...neo-embedded.com>,
	shawn guo <shawn.guo@...aro.org>,
	thierry reding <thierry.reding@...onic-design.de>,
	linux-kernel@...r.kernel.org, kernel@...gutronix.de,
	Philipp Zabel <p.zabel@...gutronix.de>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 7/9] pwm i.MX: fix clock lookup

On Thu, Sep 06, 2012 at 08:31:58PM +0200, Benoît Thébaudeau wrote:
> On Thursday, September 6, 2012 2:48:13 PM, Sascha Hauer wrote:
> > 
> > +	int ret;
> > +
> > +	ret = clk_prepare_enable(imx->clk_ipg);
> > +	if (ret)
> > +		return ret;
> >  
> > -	return imx->config(chip, pwm, duty_ns, period_ns);
> > +	ret = imx->config(chip, pwm, duty_ns, period_ns);
> > +
> > +	clk_disable_unprepare(imx->clk_ipg);
> > +
> > +	return ret;
> >  }
> >  
> >  static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device
> >  *pwm)
> > @@ -169,7 +179,7 @@ static int imx_pwm_enable(struct pwm_chip *chip,
> > struct pwm_device *pwm)
> >  	struct imx_chip *imx = to_imx_chip(chip);
> >  	int ret;
> >  
> > -	ret = clk_prepare_enable(imx->clk);
> > +	ret = clk_prepare_enable(imx->clk_per);
> >  	if (ret)
> >  		return ret;
> 
> Have you tested that this actually works on i.MX53?
> 
> I have tested it successfully on i.MX35 (with a few additions to platform code).
> But i.MX35 has a single bit controlling both PWM IPG and PER clock gates.
> 
> On i.MX53, there are 2 separate control bits for these. So, if ipg clk is
> strictly required to access PWM registers, even if per clk is enabled, this code
> should not work without adding

I tested this on i.MX53, but you're right, this seems to be wrong. I'll
recheck tomorrow.

Sascha


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