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

[Nicolin Chen <nicoleotsuka@gmail.com>]

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:
> > 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()
> > }
> 
> 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