[U-Boot] [PATCH] mmc: modified calculated mmc-capacity & set mmc trans_speed

[Andy Fleming]

On Fri, May 7, 2010 at 1:45 AM, Jae hoon Chung <jh80.chung at gmail.com> wrote:
> Dear Andy
>
> Thanks for your comment..
> but i have some question...
>
> 2010/5/7 Andy Fleming <afleming at gmail.com>:
>> On Wed, Apr 7, 2010 at 10:36 PM, Jae hoon Chung <jh80.chung at gmail.com> wrote:
>>> The patches do the following
>>> 1. If mmc size is more than 2GB , we need to calculated using the
>>> extended csd register.
>>
>> This description is slightly inaccurate.  I have encountered MMC cards
>> with 4GB capacity, which are not actually high-capacity cards.  But
>> certainly there's a bug in the current code where high-capacity MMC
>> cards are not getting proper size calculations.
>>
>
> that means 4GB capacity is not high-capacity cards, right?
> i understood that higher than 2GB is supported high-capacity..
> if i mis-understood, i'll check the spec.


Well, the spec says anything over 2GB is high capacity, and should be
accessed using block addressing.  However, the 4GB card I used
reported itself as not high-capacity, and was addressable via byte
addressing.  This works, because 4GB is addressable that way, but it's
technically in violation of the spec.


>
>>
>>> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
>>> index cf4ea16..c985924 100644
>>> --- a/drivers/mmc/mmc.c
>>> +++ b/drivers/mmc/mmc.c
>>> @@ -410,6 +410,10 @@ int mmc_change_freq(struct mmc *mmc)
>>>        if (ext_csd[212] || ext_csd[213] || ext_csd[214] || ext_csd[215])
>>>                mmc->high_capacity = 1;
>>>
>>> +       if (mmc->high_capacity)
>>> +               mmc->capacity = ((ext_csd[215] << 24) | (ext_csd[214] << 16) |
>>> +                               (ext_csd[213] << 8) | ext_csd[212]);
>>> +
>>
>>
>> This is off by a factor of block size.  Capacity is supposed to be the
>> size in bytes, and this sets it to the size in blocks, I believe.
>>
>> Hmm... I don't like that we are now doing the calculation twice for
>> high-capacity MMC cards, but I guess that's fine for now, as this only
>> affects v4 and higher, and extracting it is a bit more of a pain than
>> I originally thought.
>>
>> On a side note, does this mean you have a high-capacity MMC card?  And
>> can you point me to a place to get one?  We've been trying to test MMC
>> high-capacity for a while, and have yet to find a real one (we found
>> that 4GB one I mentioned, and it does normal byte-addressing).
>>
>
> didn't you have high-capacity card?
> we tested with 8GB moviNAND card, below is mmc card information using
> that code..


Hmm...I'm not managing to find an actual card online for sale.  Do you
have a link?  We had a high-capacity SD card, but no MMC card.


>
> Tran Speed: 52000000
> Rd Block Len: 512
> MMC version 4.3
> High Capacity: Yes
> Capacity: 7840 MByte
> Bus Width: 4-bit
>
> and if card is higher than 2GB, access mode selected sector mode..
> why does card do normal byte-addressing?

Yours is clearly a proper high-capacity card.  :)