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

Madhusudhan
2009-07-30T01:06:23Z

> -----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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