Re: [PATCH V2 4/32] mmc: add ability to save power by powering offcards

[Adrian Hunter]

Madhusudhan wrote:
> > -----Original Message-----
> > From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap-
> > owner@xxxxxxxxxxxxxxx] On Behalf Of Adrian Hunter
> > Sent: Tuesday, July 28, 2009 5:39 AM
> > To: Andrew Morton
> > Cc: Jarkko Lavinen; Adrian Hunter; linux-omap Mailing List; Pierre Ossman;
> > Denis Karpov; Matt Fleming; lkml
> > Subject: [PATCH V2 4/32] mmc: add ability to save power by powering off
> > cards
> >
> > From e6355578d082d94707c8fda1e1342c478019b5c8 Mon Sep 17 00:00:00 2001
> > From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > Date: Mon, 11 May 2009 12:20:57 +0300
> > Subject: [PATCH] mmc: add ability to save power by powering off cards
> >
> > Power can be saved by powering off cards that are not
> > in use.  This is similar to suspend / resume except
> > it is under the control of the driver, and does not
> > require any power management support.  It can only
> > be used when the driver can monitor whether the card
> > is removed, otherwise it is unsafe.  This is possible
> > because, unlike suspend, the driver still receives
> > card detect and / or cover switch interrupts.
> >
> > Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > ---
> >  drivers/mmc/core/core.c  |   34 ++++++++++++++++++++++++++++++++++
> >  drivers/mmc/core/core.h  |    2 ++
> >  drivers/mmc/core/mmc.c   |   11 +++++++++++
> >  drivers/mmc/core/sd.c    |   11 +++++++++++
> >  include/linux/mmc/host.h |    3 +++
> >  5 files changed, 61 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> > index bab5015..39f7bd1 100644
> > --- a/drivers/mmc/core/core.c
> > +++ b/drivers/mmc/core/core.c
> > @@ -1145,6 +1145,40 @@ void mmc_stop_host(struct mmc_host *host)
> >  	mmc_power_off(host);
> >  }
> >
> > +void mmc_power_save_host(struct mmc_host *host)
> > +{
> > +	mmc_bus_get(host);
> > +
> > +	if (!host->bus_ops || host->bus_dead || !host->bus_ops-
> > > power_restore) {
> > +		mmc_bus_put(host);
> > +		return;
> > +	}
> > +
> > +	if (host->bus_ops->power_save)
> > +		host->bus_ops->power_save(host);
> > +
> > +	mmc_bus_put(host);
> > +
> > +	mmc_power_off(host);
> > +}
> > +EXPORT_SYMBOL(mmc_power_save_host);
> > +
> > +void mmc_power_restore_host(struct mmc_host *host)
> > +{
> > +	mmc_bus_get(host);
> > +
> > +	if (!host->bus_ops || host->bus_dead || !host->bus_ops-
> > > power_restore) {
> > +		mmc_bus_put(host);
> > +		return;
> > +	}
> > +
> > +	mmc_power_up(host);
> > +	host->bus_ops->power_restore(host);
> > +
> > +	mmc_bus_put(host);
> > +}
> > +EXPORT_SYMBOL(mmc_power_restore_host);
> > +
>
> Who calls these exported functions " mmc_power_save_host" and "
> mmc_power_restore_host"? 

The present design has the host driver calling them i.e. for us it
is omap_hsmmc.  See the "support for deeper power saving states"
patch.


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