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

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

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.

Thank you for the input. That's the exact part I couldn't be sure.
And I agree that adding a check for AC97 will be safer while this
may keeps itself removable if being unnecessary.

Thanks
Nicolin