Re: [PATCH v4 09/15] mmc: sdhci: enable preset value after uhs initialization

[zhangfei gao <zhangfei.gao@gmail.com>]

On Thu, May 5, 2011 at 2:49 AM, Arindam Nath <arindam.nath@amd.com> wrote:
> According to the Host Controller spec v3.00, setting Preset Value Enable
> in the Host Control2 register lets SDCLK Frequency Select, Clock Generator
> Select and Driver Strength Select to be set automatically by the Host
> Controller based on the UHS-I mode set. This patch enables this feature.
> Since Preset Value Enable makes sense only for UHS-I cards, we enable this
> feature after successfull UHS-I initialization. We also reset Preset Value
> Enable next time before initialization.
>
> Signed-off-by: Arindam Nath <arindam.nath@amd.com>
> Reviewed-by: Philip Rakity <prakity@marvell.com>
> Tested-by: Philip Rakity <prakity@marvell.com>

Acked-by: Zhangfei Gao<zhangfei.gao@marvell.com>
Verified with Toshiba uhs card and general hs card,   on mmp2 in SDMA mode.
> ---
>  drivers/mmc/core/sd.c    |   11 +++++++++++
>  drivers/mmc/host/sdhci.c |   32 ++++++++++++++++++++++++++++++++
>  include/linux/mmc/host.h |    1 +
>  3 files changed, 44 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index 84cb8c3..851c8fc 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -931,6 +931,13 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
>
>                /* Card is an ultra-high-speed card */
>                mmc_sd_card_set_uhs(card);
> +
> +               /*
> +                * Since initialization is now complete, enable preset
> +                * value registers for UHS-I cards.
> +                */
> +               if (host->ops->enable_preset_value)
> +                       host->ops->enable_preset_value(host, 1);
>        } else {
>                /*
>                 * Attempt to change to high-speed (if supported)
> @@ -1101,6 +1108,10 @@ int mmc_attach_sd(struct mmc_host *host)
>        if (err)
>                return err;
>
> +       /* Disable preset value enable if already set since last time */
> +       if (host->ops->enable_preset_value)
> +               host->ops->enable_preset_value(host, 0);
> +
>        err = mmc_send_app_op_cond(host, 0, &ocr);
>        if (err)
>                return err;
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 85775cf..cb767a0 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1655,6 +1655,37 @@ out:
>        return err;
>  }
>
> +static void sdhci_enable_preset_value(struct mmc_host *mmc, int enable)
> +{
> +       struct sdhci_host *host;
> +       u16 ctrl;
> +       unsigned long flags;
> +
> +       host = mmc_priv(mmc);
> +
> +       /* Host Controller v3.00 defines preset value registers */
> +       if (host->version < SDHCI_SPEC_300)
> +               return;
> +
> +       spin_lock_irqsave(&host->lock, flags);
> +
> +       ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +
> +       /*
> +        * We only enable or disable Preset Value if they are not already
> +        * enabled or disabled respectively. Otherwise, we bail out.
> +        */
> +       if (enable && !(ctrl & SDHCI_CTRL_PRESET_VAL_ENABLE)) {
> +               ctrl |= SDHCI_CTRL_PRESET_VAL_ENABLE;
> +               sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +       } else if (!enable && (ctrl & SDHCI_CTRL_PRESET_VAL_ENABLE)) {
> +               ctrl &= ~SDHCI_CTRL_PRESET_VAL_ENABLE;
> +               sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +       }
> +
> +       spin_unlock_irqrestore(&host->lock, flags);
> +}
> +
>  static const struct mmc_host_ops sdhci_ops = {
>        .request        = sdhci_request,
>        .set_ios        = sdhci_set_ios,
> @@ -1662,6 +1693,7 @@ static const struct mmc_host_ops sdhci_ops = {
>        .enable_sdio_irq = sdhci_enable_sdio_irq,
>        .start_signal_voltage_switch    = sdhci_start_signal_voltage_switch,
>        .execute_tuning                 = sdhci_execute_tuning,
> +       .enable_preset_value            = sdhci_enable_preset_value,
>  };
>
>  /*****************************************************************************\
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index ca7007f..2209e01 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -137,6 +137,7 @@ struct mmc_host_ops {
>
>        int     (*start_signal_voltage_switch)(struct mmc_host *host, struct mmc_ios *ios);
>        int     (*execute_tuning)(struct mmc_host *host);
> +       void    (*enable_preset_value)(struct mmc_host *host, int enable);
>  };
>
>  struct mmc_card;
> --
> 1.7.1
>
>