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

[Jaehoon Chung]

Hi Siva,

On 01/22/2018 08:03 PM, Siva Durga Prasad Paladugu wrote:
> Hi Jaehoon,
> 
>> -----Original Message-----
>> From: Jaehoon Chung [mailto:jh80.chung at samsung.com]
>> Sent: Thursday, January 18, 2018 1:46 PM
>> To: Siva Durga Prasad Paladugu <sivadur at xilinx.com>; u-
>> boot at lists.denx.de
>> Cc: Vipul Kumar <vipulk at xilinx.com>; Vipul Kumar <vipulk at xilinx.com>;
>> Siva Durga Prasad Paladugu <sivadur at xilinx.com>
>> Subject: Re: [RFC PATCH] mmc: Skipping the MMC initialization at the boot
>> time
>>
>> 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?
> Yes, there may be case, where we have both controllers enabled but user would like to
> Communicate with only one at u-boot and this selection also depends on environment
> Or something which will be updated from external world then in this case, user will initialize
> Later as per his wish. This may save bootime as it initializes only the required one and choice of 
> which one to initialize

Then did you check how much time can save? 
If user want to save the booting time, will not enter to uboot console?
Well..I didn't agree about saving the booting time.

If you need to add this config, could you explain in more detail.
And how many board do enable this config in ./configs/ ?

Best Regards,
Jaehoon Chung

> 
> Thanks,
> Siva
> 
>>
>>>
>>> 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
>>>
>>> This email and any attachments are intended for the sole use of the
>> named recipient(s) and contain(s) confidential information that may be
>> proprietary, privileged or copyrighted under applicable law. If you are not
>> the intended recipient, do not read, copy, or forward this email message or
>> any attachments. Delete this email message and any attachments
>> immediately.
>>>
>>>
>>>
>