[PATCH 4/8] mmc: mmci: Use ios_handler to save power

[Vitaly Wool]

Hi Ulf,

On Tue, Jan 17, 2012 at 3:34 PM, Ulf Hansson <ulf.hansson at stericsson.com> wrote:
> To disable a levelshifter when we are in an idle state will
> decrease current consumption. We make use of the ios_handler
> at runtime suspend and at regular suspend to accomplish this.
>
> Of course depending on the used levelshifter the decrease of
> current differs. For ST6G3244ME the value is up to ~200 uA.
>
> Tested-by: Linus Walleij <linus.walleij at linaro.org>
> Signed-off-by: Ulf Hansson <ulf.hansson at stericsson.com>
> Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
> ---
>  drivers/mmc/host/mmci.c |   19 ++++++++++++++++++-
>  1 files changed, 18 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index a7c8f8f..76ce2cd 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -1505,10 +1505,22 @@ static int mmci_save(struct amba_device *dev)
>  {
>        struct mmc_host *mmc = amba_get_drvdata(dev);
>        unsigned long flags;
> +       struct mmc_ios ios;
> +       int ret = 0;
>
>        if (mmc) {
>                struct mmci_host *host = mmc_priv(mmc);
>
> +               /* Let the ios_handler act on a POWER_OFF to save power. */
> +               if (host->plat->ios_handler) {
> +                       memcpy(&ios, &mmc->ios, sizeof(struct mmc_ios));
> +                       ios.power_mode = MMC_POWER_OFF;
> +                       ret = host->plat->ios_handler(mmc_dev(mmc),
> +                                                     &ios);
> +                       if (ret)
> +                               return ret;
> +               }
> +
>                spin_lock_irqsave(&host->lock, flags);
>
>                /*
> @@ -1527,7 +1539,7 @@ static int mmci_save(struct amba_device *dev)
>                amba_vcore_disable(dev);
>        }
>
> -       return 0;
> +       return ret;
>  }
>
>  static int mmci_restore(struct amba_device *dev)
> @@ -1550,6 +1562,11 @@ static int mmci_restore(struct amba_device *dev)
>                writel(MCI_IRQENABLE, host->base + MMCIMASK0);
>
>                spin_unlock_irqrestore(&host->lock, flags);
> +
> +               /* Restore settings done by the ios_handler. */
> +               if (host->plat->ios_handler)
> +                       host->plat->ios_handler(mmc_dev(mmc),
> +                                               &mmc->ios);
>        }
>
>        return 0;

this patch is a disaster because it cuts off the chip's power on
suspend regardless of whether MMC_PM_KEEP_POWER flag has been set or
not. Simply put: it breaks everything This patch therefore gets a
strongest *NACK* from me.

Thanks,
   Vitaly