Re: [PATCH 2/2] dmaengine: shdma: add runtime- and system-level power management

Guennadi Liakhovetski
2011-05-02T09:04:44Z

On Mon, 2 May 2011, Koul, Vinod wrote:

> On Fri, 2011-04-29 at 19:09 +0200, Guennadi Liakhovetski wrote:
> > This patch extends and fixes runtime power management in the shdma
> > driver to support powering down the DMA controller and adds support
> > for system-level suspend and resume.
> >
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > ---
> > drivers/dma/shdma.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++
> > drivers/dma/shdma.h | 1 +
> > 2 files changed, 69 insertions(+), 0 deletions(-)
> >
>
> >
> > +static int sh_dmae_runtime_suspend(struct device *dev)
> > +{
> > + return 0;
> > +}
> Don't you need to initialize you device on resume...????

Hm, yes, but this is suspend... Resume is below. Sorry, I probably don't
understand your question.

> > +
> > +static int sh_dmae_runtime_resume(struct device *dev)
> > +{
> > + struct sh_dmae_device *shdev = dev_get_drvdata(dev);
> > +
> > + return sh_dmae_rst(shdev);
> > +}
> > +
> > +#ifdef CONFIG_PM
> This should be removed...

You mean, these functions just won't be called, but this way we save a
couple of bytes if PM is not set, don't we?

> > +static int sh_dmae_suspend(struct device *dev)
> > +{
> > + struct sh_dmae_device *shdev = dev_get_drvdata(dev);
> > + int i;
> > +
> > + for (i = 0; i < shdev->pdata->channel_num; i++) {
> > + struct sh_dmae_chan *sh_chan = shdev->chan[i];
> > + if (sh_chan->descs_allocated)
> > + sh_chan->pm_error = pm_runtime_put_sync(dev);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int sh_dmae_resume(struct device *dev)
> > +{
> > + struct sh_dmae_device *shdev = dev_get_drvdata(dev);
> > + int i;
> > +
> > + for (i = 0; i < shdev->pdata->channel_num; i++) {
> > + struct sh_dmae_chan *sh_chan = shdev->chan[i];
> > + struct sh_dmae_slave *param = sh_chan->common.private;
> > +
> > + if (!sh_chan->descs_allocated)
> > + continue;
> > +
> > + if (!sh_chan->pm_error)
> > + pm_runtime_get_sync(dev);
> > +
> > + if (param) {
> > + const struct sh_dmae_slave_config *cfg = param->config;
> > + dmae_set_dmars(sh_chan, cfg->mid_rid);
> > + dmae_set_chcr(sh_chan, cfg->chcr);
> > + } else {
> > + dmae_init(sh_chan);
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +#else
> > +#define sh_dmae_suspend NULL
> > +#define sh_dmae_resume NULL
> > +#endif
> > +
> > +const struct dev_pm_ops sh_dmae_pm = {
> > + .suspend = sh_dmae_suspend,
> > + .resume = sh_dmae_resume,
> > + .runtime_suspend = sh_dmae_runtime_suspend,
> > + .runtime_resume = sh_dmae_runtime_resume,
> > +};
> > +
> > static struct platform_driver sh_dmae_driver = {
> > .remove = __exit_p(sh_dmae_remove),
> > .shutdown = sh_dmae_shutdown,
> > .driver = {
> > .owner = THIS_MODULE,
> > .name = "sh-dma-engine",
> > + .pm = &sh_dmae_pm,
> > },
> > };
> >
> > diff --git a/drivers/dma/shdma.h b/drivers/dma/shdma.h
> > index 52e4fb1..3f9d3cd 100644
> > --- a/drivers/dma/shdma.h
> > +++ b/drivers/dma/shdma.h
> > @@ -37,6 +37,7 @@ struct sh_dmae_chan {
> > int id; /* Raw id of this channel */
> > u32 __iomem *base;
> > char dev_id[16]; /* unique name per DMAC of channel */
> > + int pm_error;
> > };
> >
> > struct sh_dmae_device {
>
> And please remember to CC maintainers...

Sorry, will try to remember.

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer