Re: [PATCH 1/2] mmc: sdhci: Added set_power sdhci_ops handler.

Felipe Ferreri Tonello
2013-05-22T21:22:53Z

Hi Guennadi,

On Wednesday, May 22, 2013 10:30:40 PM Guennadi Liakhovetski wrote:
> On Wed, 22 May 2013, Felipe F. Tonello wrote:
> > From: "Felipe F. Tonello" <eu@felipetonello.com>
> >
> > This is useful for power managment purposes if a sdhci child host wants to
> > turn off some other peripheral also.
>
> Sorry, could you elaborate a bit? In what situations is it exactly useful?
> And why cannot the regulator API be used there?

Sorry about that.

One example that I can think of is when you have a wifi module connected as a
mmc card via sdio. So you can register a callback function in your machine
source code to turn on/off the wifi module based on the mmc host power.

I've seen this implementation in others mmc hosts, such as omap.

Regards,

Felipe

>
> Thanks
> Guennadi
>
> > Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
> > ---
> >
> > drivers/mmc/host/sdhci.c | 8 ++++++++
> > drivers/mmc/host/sdhci.h | 1 +
> > 2 files changed, 9 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 2ea429c..0a026c6 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -1244,6 +1244,10 @@ static int sdhci_set_power(struct sdhci_host *host,
> > unsigned short power)>
> > u8 pwr = 0;
> >
> > if (power != (unsigned short)-1) {
> >
> > +
> > + if (host->ops->set_power)
> > + host->ops->set_power(host, true);
> > +
> >
> > switch (1 << power) {
> >
> > case MMC_VDD_165_195:
> > pwr = SDHCI_POWER_180;
> >
> > @@ -1259,6 +1263,10 @@ static int sdhci_set_power(struct sdhci_host *host,
> > unsigned short power)>
> > default:
> > BUG();
> >
> > }
> >
> > + } else {
> > +
> > + if (host->ops->set_power)
> > + host->ops->set_power(host, false);
> >
> > }
> >
> > if (host->pwr == pwr)
> >
> > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> > index 379e09d..293d56d 100644
> > --- a/drivers/mmc/host/sdhci.h
> > +++ b/drivers/mmc/host/sdhci.h
> > @@ -294,6 +294,7 @@ struct sdhci_ops {
> >
> > void (*platform_resume)(struct sdhci_host *host);
> > void (*adma_workaround)(struct sdhci_host *host, u32 intmask);
> > void (*platform_init)(struct sdhci_host *host);
> >
> > + void (*set_power)(struct sdhci_host *host, bool power);
> >
> > };
> >
> > #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
>
> ---
> Guennadi Liakhovetski, Ph.D.
> Freelance Open-Source Software Developer
> http://www.open-technology.de/