[U-Boot] [PATCH 1/8] dm: mmc: Don't re-init when accessing environment

[Jean-Jacques Hiblot]

Hi Simon,


On 03/05/2017 04:35, Simon Glass wrote:
> Hi,
>
> On 28 April 2017 at 18:27, Simon Glass <sjg at chromium.org> wrote:
>> Hi Jean-Jacques,
>>
>> On 24 April 2017 at 02:55, Jean-Jacques Hiblot <jjhiblot at ti.com> wrote:
>>> Hi Simon,
>>>
>>> On 24/04/2017 04:02, Simon Glass wrote:
>>>> With driver model MMC is probed automatically when needed. We should not
>>>> re-init MMC each time.
>>>>
>>>> Signed-off-by: Simon Glass <sjg at chromium.org>
>>>> ---
>>>>
>>>>    common/env_mmc.c | 3 ++-
>>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/common/env_mmc.c b/common/env_mmc.c
>>>> index a5d14d448c..1611886e22 100644
>>>> --- a/common/env_mmc.c
>>>> +++ b/common/env_mmc.c
>>>> @@ -98,9 +98,10 @@ static const char *init_mmc_for_env(struct mmc *mmc)
>>>>          if (!mmc)
>>>>                  return "!No MMC card found";
>>>>    +#ifndef CONFIG_BLK
>>>>          if (mmc_init(mmc))
>>>>                  return "!MMC init failed";
>>>> -
>>>> +#endif
>>> I'm not convinced by this.  mmc_init() is the starting point of the MMC
>>> device initialization process and it must be called somehow before accessing
>>> the device and most probe() functions do not call mmc_init().
>>> The sandbox driver does it, but I'm not sure it's the right way because the
>>> MMC device initialization process takes a long time. I'd rather have the
>>> device initialized only when it's accessed for the first time not when it's
>>> probed (especially in the SPL)
>> Yes I would like that too.
>>
>> One option is to add an init() method to mmc and call that when the
>> block device is probed.
I've just discovered that in mmc_init() is now called from the 'blk' 
probe of the mc device (it wasn't on the code base I had been looking 
at). So it should be fine to remove the call to mmc_init() from 
init_mmc_for_env(). I did the test on DRA7 and it's working. So you can 
ignore my previous comment.

However I tried to go further by removing it from spl_mmc.c as well 
because mmc_init() is called from there first and then I ran into 
problems with the detection of the partitions. I don't really have time 
to look at it right now. It may be related to the fact that my env is 
not located on the boot device.

Jean-Jacques

> Do you think that would work? I can try it out in the next version perhaps.
>
> Then we have:
>
> mmc device probe - very fast, just sets up clocks, etc.
> blk device probe - slow, tries to read card, partition table, etc.
>
>>> Jean-Jacques
>>>
>>>
>>>>          if (mmc_set_env_part(mmc))
>>>>                  return "!MMC partition switch failed";
> Regards,
> Simon
>