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

Hi,

On Wed, Sep 10, 2014 at 06:30:06PM +0800, Shengjiu Wang wrote:

On Wed, Sep 10, 2014 at 08:21:18AM +0200, Markus Pargmann wrote:

quoted

On Tue, Sep 09, 2014 at 11:38:05AM -0700, Nicolin Chen wrote:

quoted

On Tue, Sep 09, 2014 at 05:18:07PM +0800, Shengjiu Wang wrote:

quoted

@@ -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()
}

If I remember correctly, there may be AC97 communication with the codec
before any substream is created. That's why we enable the SSI unit right
at the beginning for AC97 in fsl_ssi_setup_reg_vals(). So we need to
check for AC97 before disabling clocks.

Best regards,

Markus

hi Markus

I think if clk_prepare_enable() in startup(), and clk_disable_unprepare()
in shutdown can meet this requirement, right?

Yes that could work.

done:
        if (ssi_private->dai_fmt)
                _fsl_ssi_set_dai_fmt(ssi_private, ssi_private->dai_fmt);

I find that in end of probe, there is setting of dai_fmt. Can we remove this?
because this setting need to enable ipg clock, and if ac97, ipg clock can't be
disabled.

No you can't remove it. It is necessary for the DT property "fsl,mode".
Most dts do not have this property anymore because the sound cards are
setting the dai-fmt. But there are still some powerpc dts files that
contain that property.

Best regards,

Markus

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