[PATCH V2 3/3] mmc: dw_mmc: Dont cut off vqmmc and vmmc

[ulf.hansson@linaro.org (Ulf Hansson)]

On 22 August 2014 15:47, Yuvaraj Kumar C D <yuvaraj.cd@gmail.com> wrote:
> Exynos 5250 and 5420 based boards uses built-in CD# line for card
> detection.But unfortunately CD# line is on the same voltage rails
> as of I/O voltage rails. When we cut off vqmmc,the consequent card
> detection will break in these boards.

I am not sure I follow here.

Is the card detect mechanism handled internally by the dw_mmc controller?

I thought HW engineers long time ago realized that this should be done
separately on a GPIO line to be able to save power while waiting for a
card to be inserted. But that's not case then?

>
> These hosts (obviously) need to keep vqmmc (and thus vmmc) on all the
> time, even when the mmc core tells them to power off. However, one
> problem is that these cards won't properly handle mmc_power_cycle().
> That's needed to handle error cases when trying to switch voltages
> (see 0797e5f mmc:core: Fixup signal voltage switch).
>
> This patch adds a new MMC_POWER_OFF_HARD mode when it's doing a power
> cycle.  This mode differs from the normal MMC_POWER_OFF mode in that
> the mmc core will promise to power the slot back on before it expects
> the host to detect card insertion or removal.
>
> Also if we let alone the vqmmc turned on when vmmc turned off, the
> card could have half way powered and this can damage the card. So
> this patch adds a check so that, if the board used the built-in
> card detection mechanism i.e through CDETECT, it will not turned
> down vqmmc and vmmc both.

Why does vmmc needs to be enabled when there are no card inserted?
That can't be right?

Kind regards
Uffe

>
> Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> ---
> changes from v1:
>         1.added a new MMC_POWER_OFF_HARD mode as per Doug Anderson's suggestion.
>         2.added dw_mci_exynos_post_init() to perform the host specific post
>           initialisation.
>         3.added a new flag MMC_CAP2_CD_NEEDS_POWER for host->caps2.
>
>  drivers/mmc/core/core.c          |   16 ++++++++++++++--
>  drivers/mmc/core/debugfs.c       |    3 +++
>  drivers/mmc/host/dw_mmc-exynos.c |   12 ++++++++++++
>  drivers/mmc/host/dw_mmc.c        |   25 +++++++++++++++++++++++++
>  drivers/mmc/host/dw_mmc.h        |    2 ++
>  include/linux/mmc/host.h         |    2 ++
>  6 files changed, 58 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 68f5f4b..79ced36 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1564,9 +1564,9 @@ void mmc_power_up(struct mmc_host *host, u32 ocr)
>         mmc_host_clk_release(host);
>  }
>
> -void mmc_power_off(struct mmc_host *host)
> +void _mmc_power_off(struct mmc_host *host, unsigned char power_mode)
>  {
> -       if (host->ios.power_mode == MMC_POWER_OFF)
> +       if (host->ios.power_mode == power_mode)
>                 return;
>
>         mmc_host_clk_hold(host);
> @@ -1579,6 +1579,7 @@ void mmc_power_off(struct mmc_host *host)
>                 host->ios.chip_select = MMC_CS_DONTCARE;
>         }
>         host->ios.power_mode = MMC_POWER_OFF;
> +       host->ios.power_mode = power_mode;
>         host->ios.bus_width = MMC_BUS_WIDTH_1;
>         host->ios.timing = MMC_TIMING_LEGACY;
>         mmc_set_ios(host);
> @@ -1593,9 +1594,20 @@ void mmc_power_off(struct mmc_host *host)
>         mmc_host_clk_release(host);
>  }
>
> +void mmc_power_off(struct mmc_host *host)
> +{
> +       _mmc_power_off(host, MMC_POWER_OFF);
> +}
> +
>  void mmc_power_cycle(struct mmc_host *host, u32 ocr)
>  {
>         mmc_power_off(host);
> +       /* If host normally ignores MMC_POWER_OFF, tell it to pay attention */
> +       if (host->caps2 & MMC_CAP2_CD_NEEDS_POWER)
> +               _mmc_power_off(host, MMC_POWER_OFF_HARD);
> +       else
> +               _mmc_power_off(host, MMC_POWER_OFF);
> +
>         /* Wait at least 1 ms according to SD spec */
>         mmc_delay(1);
>         mmc_power_up(host, ocr);
> diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c
> index 91eb162..3d9c5a3 100644
> --- a/drivers/mmc/core/debugfs.c
> +++ b/drivers/mmc/core/debugfs.c
> @@ -108,6 +108,9 @@ static int mmc_ios_show(struct seq_file *s, void *data)
>         case MMC_POWER_ON:
>                 str = "on";
>                 break;
> +       case MMC_POWER_OFF_HARD:
> +               str = "hard off";
> +               break;
>         default:
>                 str = "invalid";
>                 break;
> diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
> index 0fbc53a..4e26049 100644
> --- a/drivers/mmc/host/dw_mmc-exynos.c
> +++ b/drivers/mmc/host/dw_mmc-exynos.c
> @@ -17,6 +17,7 @@
>  #include <linux/mmc/mmc.h>
>  #include <linux/of.h>
>  #include <linux/of_gpio.h>
> +#include <linux/mmc/slot-gpio.h>
>  #include <linux/slab.h>
>
>  #include "dw_mmc.h"
> @@ -217,6 +218,16 @@ static void dw_mci_exynos_set_ios(struct dw_mci *host, struct mmc_ios *ios)
>         }
>  }
>
> +static void dw_mci_exynos_post_init(struct dw_mci_slot *slot)
> +{
> +       struct dw_mci_board *brd = slot->host->pdata;
> +       struct mmc_host *mmc = slot->mmc;
> +
> +       if (!(brd->quirks & DW_MCI_QUIRK_BROKEN_CARD_DETECTION) &&
> +                       IS_ERR_VALUE(mmc_gpio_get_cd(mmc)))
> +               mmc->caps2 |= MMC_CAP2_CD_NEEDS_POWER;
> +}
> +
>  static int dw_mci_exynos_parse_dt(struct dw_mci *host)
>  {
>         struct dw_mci_exynos_priv_data *priv;
> @@ -399,6 +410,7 @@ static const struct dw_mci_drv_data exynos_drv_data = {
>         .prepare_command        = dw_mci_exynos_prepare_command,
>         .set_ios                = dw_mci_exynos_set_ios,
>         .parse_dt               = dw_mci_exynos_parse_dt,
> +       .post_init              = dw_mci_exynos_post_init,
>         .execute_tuning         = dw_mci_exynos_execute_tuning,
>  };
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index f20b4b8..6f2c681 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -972,6 +972,22 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
>         spin_unlock_bh(&host->lock);
>  }
>
> +/*
> + * some of the boards use controller CD line for card detection.Unfortunately
> + * CD line is bind to the same volatge domain as of the IO lines.If we turn off
> + * IO voltage domain, CD line wont work.
> + * Return true when controller CD line is used for card detection or return
> + * false.
> + */
> +static bool dw_mci_builtin_cd(struct dw_mci_slot *slot)
> +{
> +       struct dw_mci_board *brd = slot->host->pdata;
> +       struct mmc_host *mmc = slot->mmc;
> +
> +       return  (!(brd->quirks & DW_MCI_QUIRK_BROKEN_CARD_DETECTION) &&
> +                       IS_ERR_VALUE(mmc_gpio_get_cd(mmc))) ? 1 : 0;
> +}
> +
>  static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  {
>         struct dw_mci_slot *slot = mmc_priv(mmc);
> @@ -1043,6 +1059,10 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>                 mci_writel(slot->host, PWREN, regs);
>                 break;
>         case MMC_POWER_OFF:
> +               if (dw_mci_builtin_cd(slot) &&
> +                               !test_bit(DW_MMC_CARD_PRESENT, &slot->flags))
> +                       return;
> +
>                 if (!IS_ERR(mmc->supply.vmmc))
>                         mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
>
> @@ -1055,6 +1075,8 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>                 regs &= ~(1 << slot->id);
>                 mci_writel(slot->host, PWREN, regs);
>                 break;
> +       case MMC_POWER_OFF_HARD:
> +               break;
>         default:
>                 break;
>         }
> @@ -2310,6 +2332,9 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
>         else
>                 clear_bit(DW_MMC_CARD_PRESENT, &slot->flags);
>
> +       if (drv_data && drv_data->post_init)
> +               drv_data->post_init(slot);
> +
>         ret = mmc_add_host(mmc);
>         if (ret)
>                 goto err_setup_bus;
> diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
> index 01b99e8..a3c2628 100644
> --- a/drivers/mmc/host/dw_mmc.h
> +++ b/drivers/mmc/host/dw_mmc.h
> @@ -250,6 +250,7 @@ struct dw_mci_tuning_data {
>   * @prepare_command: handle CMD register extensions.
>   * @set_ios: handle bus specific extensions.
>   * @parse_dt: parse implementation specific device tree properties.
> + * @post_init: implementation specific post initialization.
>   * @execute_tuning: implementation specific tuning procedure.
>   *
>   * Provide controller implementation specific extensions. The usage of this
> @@ -263,6 +264,7 @@ struct dw_mci_drv_data {
>         void            (*prepare_command)(struct dw_mci *host, u32 *cmdr);
>         void            (*set_ios)(struct dw_mci *host, struct mmc_ios *ios);
>         int             (*parse_dt)(struct dw_mci *host);
> +       void            (*post_init)(struct dw_mci_slot *slot);
>         int             (*execute_tuning)(struct dw_mci_slot *slot, u32 opcode,
>                                         struct dw_mci_tuning_data *tuning_data);
>  };
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 4cbf614..5eb24ff 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -42,6 +42,7 @@ struct mmc_ios {
>  #define MMC_POWER_OFF          0
>  #define MMC_POWER_UP           1
>  #define MMC_POWER_ON           2
> +#define MMC_POWER_OFF_HARD     3
>
>         unsigned char   bus_width;              /* data bus width */
>
> @@ -283,6 +284,7 @@ struct mmc_host {
>  #define MMC_CAP2_HS400         (MMC_CAP2_HS400_1_8V | \
>                                  MMC_CAP2_HS400_1_2V)
>  #define MMC_CAP2_SDIO_IRQ_NOTHREAD (1 << 17)
> +#define MMC_CAP2_CD_NEEDS_POWER (1 << 18)      /* Card detect needs power */
>
>         mmc_pm_flag_t           pm_caps;        /* supported pm features */
>
> --
> 1.7.10.4
>