RE: [PATCH V2 4/32] mmc: add ability to save power by powering off cards

From: "Madhusudhan" <madhu.cr@ti.com>
To: "'Adrian Hunter'" <adrian.hunter@nokia.com>,
	"'Andrew Morton'" <akpm@linux-foundation.org>
Cc: "'Jarkko Lavinen'" <jarkko.lavinen@nokia.com>,
	"'linux-omap Mailing List'" <linux-omap@vger.kernel.org>,
	"'Pierre Ossman'" <pierre@ossman.eu>,
	"'Denis Karpov'" <ext-denis.2.karpov@nokia.com>,
	"'Matt Fleming'" <matt@console-pimps.org>,
	"'lkml'" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH V2 4/32] mmc: add ability to save power by powering off cards
Date: Wed, 29 Jul 2009 20:05:56 -0500	[thread overview]
Message-ID: <00a001ca10b1$e4d7e390$544ff780@am.dhcp.ti.com> (raw)
In-Reply-To: <20090728103904.2371.68231.sendpatchset@ahunter-laptop>

> -----Original Message-----
> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
> owner@vger.kernel.org] 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@nokia.com>
> 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@nokia.com>
> ---
>  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"? 

>  #ifdef CONFIG_PM
> 
>  /**
> diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
> index c819eff..f7eb4c4 100644
> --- a/drivers/mmc/core/core.h
> +++ b/drivers/mmc/core/core.h
> @@ -20,6 +20,8 @@ struct mmc_bus_ops {
>  	void (*detect)(struct mmc_host *);
>  	void (*suspend)(struct mmc_host *);
>  	void (*resume)(struct mmc_host *);
> +	void (*power_save)(struct mmc_host *);
> +	void (*power_restore)(struct mmc_host *);
>  };
> 
>  void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops
> *ops);
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 3e35075..01f7226 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -549,6 +549,14 @@ static void mmc_resume(struct mmc_host *host)
> 
>  }
> 
> +static void mmc_power_restore(struct mmc_host *host)
> +{
> +	host->card->state &= ~MMC_STATE_HIGHSPEED;
> +	mmc_claim_host(host);
> +	mmc_init_card(host, host->ocr, host->card);
> +	mmc_release_host(host);
> +}
> +
>  #ifdef CONFIG_MMC_UNSAFE_RESUME
> 
>  static const struct mmc_bus_ops mmc_ops = {
> @@ -556,6 +564,7 @@ static const struct mmc_bus_ops mmc_ops = {
>  	.detect = mmc_detect,
>  	.suspend = mmc_suspend,
>  	.resume = mmc_resume,
> +	.power_restore = mmc_power_restore,
>  };
> 
>  static void mmc_attach_bus_ops(struct mmc_host *host)
> @@ -570,6 +579,7 @@ static const struct mmc_bus_ops mmc_ops = {
>  	.detect = mmc_detect,
>  	.suspend = NULL,
>  	.resume = NULL,
> +	.power_restore = mmc_power_restore,
>  };
> 
>  static const struct mmc_bus_ops mmc_ops_unsafe = {
> @@ -577,6 +587,7 @@ static const struct mmc_bus_ops mmc_ops_unsafe = {
>  	.detect = mmc_detect,
>  	.suspend = mmc_suspend,
>  	.resume = mmc_resume,
> +	.power_restore = mmc_power_restore,
>  };
> 
>  static void mmc_attach_bus_ops(struct mmc_host *host)
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index 80cccd2..debe26e 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -603,6 +603,14 @@ static void mmc_sd_resume(struct mmc_host *host)
> 
>  }
> 
> +static void mmc_sd_power_restore(struct mmc_host *host)
> +{
> +	host->card->state &= ~MMC_STATE_HIGHSPEED;
> +	mmc_claim_host(host);
> +	mmc_sd_init_card(host, host->ocr, host->card);
> +	mmc_release_host(host);
> +}
> +
>  #ifdef CONFIG_MMC_UNSAFE_RESUME
> 
>  static const struct mmc_bus_ops mmc_sd_ops = {
> @@ -610,6 +618,7 @@ static const struct mmc_bus_ops mmc_sd_ops = {
>  	.detect = mmc_sd_detect,
>  	.suspend = mmc_sd_suspend,
>  	.resume = mmc_sd_resume,
> +	.power_restore = mmc_sd_power_restore,
>  };
> 
>  static void mmc_sd_attach_bus_ops(struct mmc_host *host)
> @@ -624,6 +633,7 @@ static const struct mmc_bus_ops mmc_sd_ops = {
>  	.detect = mmc_sd_detect,
>  	.suspend = NULL,
>  	.resume = NULL,
> +	.power_restore = mmc_sd_power_restore,
>  };
> 
>  static const struct mmc_bus_ops mmc_sd_ops_unsafe = {
> @@ -631,6 +641,7 @@ static const struct mmc_bus_ops mmc_sd_ops_unsafe = {
>  	.detect = mmc_sd_detect,
>  	.suspend = mmc_sd_suspend,
>  	.resume = mmc_sd_resume,
> +	.power_restore = mmc_sd_power_restore,
>  };
> 
>  static void mmc_sd_attach_bus_ops(struct mmc_host *host)
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index bb867d2..c1cbe59 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -223,6 +223,9 @@ static inline void *mmc_priv(struct mmc_host *host)
>  extern int mmc_suspend_host(struct mmc_host *, pm_message_t);
>  extern int mmc_resume_host(struct mmc_host *);
> 
> +extern void mmc_power_save_host(struct mmc_host *host);
> +extern void mmc_power_restore_host(struct mmc_host *host);
> +
>  extern void mmc_detect_change(struct mmc_host *, unsigned long delay);
>  extern void mmc_request_done(struct mmc_host *, struct mmc_request *);
> 
> --
> 1.5.6.3
> 
> --
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