Re: [PATCH] mmc: omap_hsmmc: fix initialization order of mmc block devices

[Lokesh Vutla <a0131933@ti.com>]

On Tuesday 13 October 2015 01:14 PM, Heiko Schocher wrote:
> Hello Lokesh,
> 
> Am 13.10.2015 um 08:46 schrieb Lokesh Vutla:
>> +Nishanth,
>>
>> On Tuesday 13 October 2015 10:59 AM, Heiko Schocher wrote:
>>> On embedded devices, often there is a combination of
>>> removable mmc devices (e.g. MMC/SD cards) and hard
>>> wired ones (e.g. eMMC). Depending on the hardware
>>> configuration, the 'mmcblkN' node might change if
>>> the removable device is available or not at boot time.
>>>
>>> E.g. if the removable device is attached at boot time,
>>> it might become mmxblk0. And the hard wired one mmcblk1.
>>> But if the removable device isn't there at boot time,
>>> the hard wired one will become mmcblk0. This makes it
>>> somehow difficult to hard code the root device to the
>>> non-removable device and boot fast.
>>
>> Why not use "root=PARTUUID=${uuid}" option instead of relying on
>> mmcblk no?
>> U-Boot can easily detect your partuuid. Refer to [1] on how TI platforms
>> does this in u-boot.
> 
> Good tip ... I do not know, if it is possible to update U-Boot
> on this boards...
> 
> Current U-Boot says:
> U-Boot 2013.01.01_heads/master-gc7900a0 (2015-05-06 - 20:37:15)
> 
> I2C:   ready
> DRAM:  512 MiB
> [...]
> U-Boot# mmc rescan
> U-Boot# mmc part
> 
> Partition Map for MMC device 0  --   Partition Type: DOS
> 
> Part    Start Sector    Num Sectors     UUID            Type
>   1     63              144522          000ce343-01     0e Boot
>   2     144585          659861          000ce343-02     83
> U-Boot# part uuid mmc 0:2 uuid
> Unknown command 'part' - try 'help'
> U-Boot#
> 
> So, if this patch has no chance for mainline, please let me
> know it, thanks!
> 

IIRC, Nishanth had posted a patch something similar but got rejected for
some reason. Probably Nishanth can comment more here.

Thanks and regards,
Lokesh