[U-Boot] MMC: proposal to support multiple physical partitions

[Steve Rae]

Thanks for the response,

> -----Original Message-----
> From: Pantelis Antoniou [mailto:panto at antoniou-consulting.com]
> Sent: Tuesday, April 29, 2014 10:25
> To: Steve Rae
> Cc: u-boot at lists.denx.de; trini at ti.com; albert.u.boot at aribaud.net
> Subject: Re: MMC: proposal to support multiple physical partitions
> 
> Hi Steve,
> 
> On Apr 24, 2014, at 8:50 PM, Steve Rae wrote:
> 
[... snip ...]

> > I have two different proposals:
> > 1) overload the "int dev_num" argument with encoded  "dev_num" and
> "part_num" fields
> > -          the dev_num  in the [15:0] bits,
> > -          the part_num in the [30:16] bits,
> > -          a flag to indicate this encoding in [31] bit.
> > -          and modify mmc_bread() to handle this encoded argument, and
> implement the above code...
> > 2) create a wrapper function to perform the above code, with an added
> argument "int part_num", possibly named:
> > -          mmc_block_dev_block_read() -- so that it is similar to the original
> calling convention [mmc->block_dev.block_read], or
> > -          mmc_pbread() [PartitionBlockRead] -- so that it is similar to the
> mmc_bread() [which is the implementation of the callback function]
> >
> 
> 
> I'd rather go with the wrapper function. Perhaps it's not even needed. The
> function called is part of the block_dev (block_read/write etc).
> 
> Overwrite those with functions that implemented the switching first, and
> then call the original block* function.
>
The callback function is:
    mmc->block_dev.block_read = mmc_bread
and it accepts four arguments:
    include/part.h: unsigned long   (*block_read)(int dev,
    include/part.h-                               lbaint_t start,
    include/part.h-                               lbaint_t blkcnt,
    include/part.h-                               void *buffer);
Are you suggesting that I should add another argument to this callback?

[...snip...]

> 
> Regards
> 
> -- Pantelis