linux-kernel - Re: [PATCH V1] ASoC: fsl_ssi: refine ipg clock usage in this module

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Message-ID: <20140910081251.GA14662@audiosh1>
Date:	Wed, 10 Sep 2014 16:12:53 +0800
From:	Shengjiu Wang <shengjiu.wang@...escale.com>
To:	Nicolin Chen <nicoleotsuka@...il.com>
CC:	<timur@...i.org>, <Li.Xiubo@...escale.com>, <lgirdwood@...il.com>,
	<broonie@...nel.org>, <perex@...ex.cz>, <tiwai@...e.de>,
	<alsa-devel@...a-project.org>, <linuxppc-dev@...ts.ozlabs.org>,
	<linux-kernel@...r.kernel.org>, <mpa@...gutronix.de>
Subject: Re: [PATCH V1] ASoC: fsl_ssi: refine ipg clock usage in this module

On Tue, Sep 09, 2014 at 11:38:05AM -0700, Nicolin Chen wrote:
> On Tue, Sep 09, 2014 at 05:18:07PM +0800, Shengjiu Wang wrote:
> > @@ -1321,7 +1333,11 @@ static int fsl_ssi_probe(struct platform_device *pdev)
> >  		return -ENOMEM;
> >  	}
> >  
> > -	ssi_private->regs = devm_regmap_init_mmio(&pdev->dev, iomem,
> > +	if (ssi_private->soc->imx)
> > +		ssi_private->regs = devm_regmap_init_mmio_clk(&pdev->dev,
> > +			"ipg", iomem, &fsl_ssi_regconfig);
> > +	else
> > +		ssi_private->regs = devm_regmap_init_mmio(&pdev->dev, iomem,
> 
> As Markus mentioned, the key point here is to be compatible with those
> non-clock-name platforms.
> 
> I think it would be safer to keep the current code while adding an extra
> clk_disable_unprepare() at the end of probe() as a common routine. And
> meantime, make sure to have the call for imx only because it seems that
> the other platforms do not depend on the clock. //a bit guessing here :)
> 
> Then we can get a patch like:
> open() {
> +	clk_prepare_enable();
> 	....
> }
> 
> close() {
> 	....
> +	clk_disable_unprepare()
> }
what is the open() and close()? do you mean the fsl_ssi_startup()
and fsl_ssi_shutdown()?
> 
> probe() {
> 	clk_get();
> 	clk_prepare_enable();
> 	....
> 	if (xxx)
> -		goto err_xx;
> +		return ret;
> 	....
> +	clk_disable_unprepare();
> 	return 0;
> -err_xx:
> -	clk_disable_unprepare()
> }
If this probe() is fsl_ssi_imx_probe(), I think no need to add
clk_prepare_enable() or clk_disable_unprepare(), seems there is no 
registers accessing in this probe.
> 
> remove() {
> 	....
> -	clk_disable_unprepare()
> }
> 
> As long as you make the subject clear as 'Don't enable core/ipg clock
> when SSI's idle', I'm sure you can make them within a single patch.
> 
> And an alternative way for open() and close() is to put those code into
> pm_runtime_resume/suspend() instead (since we might have some internal
> code need to be added by using pm_runtime as well), which would make
> the further code neater IMO.
> 
> Thank you
> Nicolin
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