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

[vitalywool@gmail.com (Vitaly Wool)]

Hi Ulf,

On Tue, Jan 17, 2012 at 3:34 PM, Ulf Hansson <ulf.hansson@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@linaro.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
> Signed-off-by: Linus Walleij <linus.walleij@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