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

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Date:	Tue, 9 Sep 2014 11:38:05 -0700
From:	Nicolin Chen <nicoleotsuka@...il.com>
To:	Shengjiu Wang <shengjiu.wang@...escale.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 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()
}

probe() {
	clk_get();
	clk_prepare_enable();
	....
	if (xxx)
-		goto err_xx;
+		return ret;
	....
+	clk_disable_unprepare();
	return 0;
-err_xx:
-	clk_disable_unprepare()
}

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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