[U-Boot] [PATCH] mmc: add wrappers for MMC block_{read, write, erase}

[Stephen Warren]

On 05/29/2014 11:58 AM, Steve Rae wrote:
> Hi, Stephen
> 
> On 14-05-29 09:25 AM, Stephen Warren wrote:
>> On 05/28/2014 04:15 PM, Steve Rae wrote:
>>> Each wrapper function:
>>> - switches to the specified physical partition, then
>>> - performs the original function, and then
>>> - switches back to the original physical partition
>>> where the physical partition (aka HW partition) is
>>>    0=User, 1=Boot1, 2=Boot2, etc.
>>
>> This feels wrong; why wouldn't mmc_get_dev() return a block_dev_desc_t
>> containing block_read/block_write functions that do the HW partition
>> switching. That way, this is all completely hidden, and all client code
>> only knows about block devices, rather than having to know about
>> MMC-specific mmc_block_read/write/erase_hwpart() functions.
>>
> This goes back to the initial discussion on this mailing list (which was
> never resolved):
>   http://lists.denx.de/pipermail/u-boot/2014-April/178171.html
> This issue is that the three callback functions defined in
> 'block_desc_t' do not accept the "partition number" as an argument.
> It was suggested that we could overwrite those functions; but the
> "partition number" still needs to be passed in by:
> (1) overloading the "int dev_num" argument, or
> (2) adding another argument to the callback functions
> I assumed that neither of these was acceptable, so I have proposed these
> wrappers...

Can't the data simply be stored in the block_desc_t itself?