[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20140910064211.GA7652@Asurada>
Date: Tue, 9 Sep 2014 23:42:12 -0700
From: Nicolin Chen <nicoleotsuka@...il.com>
To: Markus Pargmann <mpa@...gutronix.de>
Cc: Shengjiu Wang <shengjiu.wang@...escale.com>,
alsa-devel@...a-project.org, lgirdwood@...il.com, tiwai@...e.de,
linux-kernel@...r.kernel.org, broonie@...nel.org, timur@...i.org,
Li.Xiubo@...escale.com, linuxppc-dev@...ts.ozlabs.org
Subject: 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:
> > 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists