linux-kernel - Re: [PATCH v2] mmc: core: Improve support for deferred regulators

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Message-ID: <CAAYSxhoGoREU-af3DD2O3+tZ8JF8nitnp1a-ZrmFW_Lj31zVPg@mail.gmail.com>
Date:	Tue, 6 May 2014 15:58:37 -0700
From:	Tim Kryger <tim.kryger@...aro.org>
To:	Chris Ball <chris@...ntf.net>, Ulf Hansson <ulf.hansson@...aro.org>
Cc:	Tim Kryger <tim.kryger@...aro.org>,
	Mike Looijmans <mike.looijmans@...ic.nl>,
	Andrew Bresticker <abrestic@...omium.org>,
	Linux MMC List <linux-mmc@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mmc: core: Improve support for deferred regulators

On Tue, May 6, 2014 at 3:57 PM, Tim Kryger <tim.kryger@...aro.org> wrote:
> Callers of mmc_regulator_get_supply could benefit from knowing if either
> of the regulators are present but not yet available.  Since callers do
> not currently examine the return value, modify this function to return
> zero or -EPROBE_DEFER if either regulator get returns the same.
>
> Furthermore, since callers check vmmc/vqmmc using IS_ERR and can deal
> with absent regulators, switch to devm_regulator_get_optional. This has
> the added benefit of allowing this function to behave correctly even in
> the !CONFIG_REGULATOR case such that the stub can be removed.
>
> Signed-off-by: Tim Kryger <tim.kryger@...aro.org>
> ---

Changes since v1:
  - Removed stub function for !CONFIG_REGULATOR case

>  drivers/mmc/core/core.c  |   31 +++++++++++++++++++------------
>  include/linux/mmc/host.h |    8 ++------
>  2 files changed, 21 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index acbc3f2..2d9f6c5 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1310,31 +1310,38 @@ int mmc_regulator_set_ocr(struct mmc_host *mmc,
>  }
>  EXPORT_SYMBOL_GPL(mmc_regulator_set_ocr);
>
> +#endif /* CONFIG_REGULATOR */
> +
>  int mmc_regulator_get_supply(struct mmc_host *mmc)
>  {
>         struct device *dev = mmc_dev(mmc);
> -       struct regulator *supply;
>         int ret;
>
> -       supply = devm_regulator_get(dev, "vmmc");
> -       mmc->supply.vmmc = supply;
> +       mmc->supply.vmmc = devm_regulator_get_optional(dev, "vmmc");
>         mmc->supply.vqmmc = devm_regulator_get_optional(dev, "vqmmc");
>
> -       if (IS_ERR(supply))
> -               return PTR_ERR(supply);
> +       if (IS_ERR(mmc->supply.vmmc)) {
> +               if (PTR_ERR(mmc->supply.vmmc) == -EPROBE_DEFER)
> +                       return -EPROBE_DEFER;
> +               dev_info(dev, "No vmmc regulator found\n");
> +       } else {
> +               ret = mmc_regulator_get_ocrmask(mmc->supply.vmmc);
> +               if (ret > 0)
> +                       mmc->ocr_avail = ret;
> +               else
> +                       dev_warn(dev, "Failed getting OCR mask: %d\n", ret);
> +       }
>
> -       ret = mmc_regulator_get_ocrmask(supply);
> -       if (ret > 0)
> -               mmc->ocr_avail = ret;
> -       else
> -               dev_warn(mmc_dev(mmc), "Failed getting OCR mask: %d\n", ret);
> +       if (IS_ERR(mmc->supply.vqmmc)) {
> +               if (PTR_ERR(mmc->supply.vqmmc) == -EPROBE_DEFER)
> +                       return -EPROBE_DEFER;
> +               dev_info(dev, "No vqmmc regulator found\n");
> +       }
>
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(mmc_regulator_get_supply);
>
> -#endif /* CONFIG_REGULATOR */
> -
>  /*
>   * Mask off any voltages we don't support and select
>   * the lowest voltage
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index cb61ea4..cfa2ecb 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -396,7 +396,6 @@ int mmc_regulator_get_ocrmask(struct regulator *supply);
>  int mmc_regulator_set_ocr(struct mmc_host *mmc,
>                         struct regulator *supply,
>                         unsigned short vdd_bit);
> -int mmc_regulator_get_supply(struct mmc_host *mmc);
>  #else
>  static inline int mmc_regulator_get_ocrmask(struct regulator *supply)
>  {
> @@ -409,13 +408,10 @@ static inline int mmc_regulator_set_ocr(struct mmc_host *mmc,
>  {
>         return 0;
>  }
> -
> -static inline int mmc_regulator_get_supply(struct mmc_host *mmc)
> -{
> -       return 0;
> -}
>  #endif
>
> +int mmc_regulator_get_supply(struct mmc_host *mmc);
> +
>  int mmc_pm_notify(struct notifier_block *notify_block, unsigned long, void *);
>
>  static inline int mmc_card_is_removable(struct mmc_host *host)
> --
> 1.7.9.5
>
--
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