[U-Boot] [RFC PATCH] mmc: Skipping the MMC initialization at the boot time

[Jaehoon Chung]

On 01/18/2018 02:40 PM, Siva Durga Prasad Paladugu wrote:
> From: Vipul Kumar <vipul.kumar at xilinx.com>
> 
> By enabling CONFIG_SKIP_EARLY_MMC_INIT config, user can skip the MMC
> initialization at the boot time. After getting the u-boot console,
> user can select the device using mmc dev and can communicate with that.
> This is useful where user don't want to perform mmc initialization
> while booting and can do explicitly later as per choice.

Is there any use-case? What benefit can user have with this config?
According to commit-msg, user will choose the mmc device later.
Is it same with initializing at booting time?

> 
> Signed-off-by: Vipul Kumar <vipulk at xilinx.com>
> Signed-off-by: Siva Durga Prasad Paladugu <sivadur at xilinx.com>
> ---
>  common/board_r.c    | 4 ++--
>  drivers/mmc/Kconfig | 7 +++++++
>  2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/common/board_r.c b/common/board_r.c
> index 2a9df6b..8727b93 100644
> --- a/common/board_r.c
> +++ b/common/board_r.c
> @@ -421,7 +421,7 @@ static int initr_onenand(void)
>  }
>  #endif
> 
> -#ifdef CONFIG_MMC
> +#if defined(CONFIG_MMC) && !defined(CONFIG_SKIP_EARLY_MMC_INIT)
>  static int initr_mmc(void)
>  {
>         puts("MMC:   ");
> @@ -768,7 +768,7 @@ static init_fnc_t init_sequence_r[] = {
>  #ifdef CONFIG_CMD_ONENAND
>         initr_onenand,
>  #endif
> -#ifdef CONFIG_MMC
> +#if defined(CONFIG_MMC) && !defined(CONFIG_SKIP_EARLY_MMC_INIT)
>         initr_mmc,
>  #endif
>         initr_env,
> diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
> index ab0627a..05b1503 100644
> --- a/drivers/mmc/Kconfig
> +++ b/drivers/mmc/Kconfig
> @@ -40,6 +40,13 @@ config SPL_DM_MMC
> 
>  if MMC
> 
> +config SKIP_EARLY_MMC_INIT
> +       bool "Skip the MMC initialization at boot time"
> +       help
> +         Skip the MMC initialization at the boot time. After getting the u-boot
> +         console, user need to set mmc device and after setting the mmc dev, user
> +         can communicate with that device.
> +
>  config ARM_PL180_MMCI
>         bool "ARM AMBA Multimedia Card Interface and compatible support"
>         depends on DM_MMC && OF_CONTROL
> --
> 2.7.4
> 
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