[U-Boot] [PATCH 3/4] mmc: exynos dwmmc: check boot mode before init dwmmc

[Przemyslaw Marczak]

Hi,

On 02/19/2015 05:45 PM, Tom Rini wrote:
> On Thu, Feb 19, 2015 at 03:36:57PM +0100, Przemyslaw Marczak wrote:
>> Hello Tom,
>>
>> On 02/19/2015 03:03 PM, Tom Rini wrote:
>>> On Wed, Feb 18, 2015 at 11:50:41AM +0100, Przemyslaw Marczak wrote:
>>>> Hello Simon,
>>>>
>>>> On 02/18/2015 06:02 AM, Simon Glass wrote:
>>>>> Hi Przemyslaw,
>>>>>
>>>>> On 17 February 2015 at 06:09, Przemyslaw Marczak <p.marczak at samsung.com> wrote:
>>>>>> Before this commit, the mmc devices were always registered
>>>>>> in the same order. So dwmmc channel 0 was registered as mmc 0,
>>>>>> channel 1 as mmc 1, etc.
>>>>>> In case of possibility to boot from more then one device,
>>>>>> the CONFIG_SYS_MMC_ENV_DEV should always point to right mmc device.
>>>>>>
>>>>>> This can be achieved by init boot device as first, so it will be
>>>>>> always registered as mmc 0. Thanks to this, the 'saveenv' command
>>>>>> will work fine for all mmc boot devices.
>>>>>>
>>>>>> Exynos based boards usually uses mmc host channels configuration:
>>>>>> - 0, or 0+1 for 8 bit  - as a default boot device (usually eMMC)
>>>>>> - 2 for 4bit - as an optional boot device (usually SD card slot)
>>>>>>
>>>>>> And usually the boot order is defined by OM pin configuration,
>>>>>> which can be changed in a few ways, eg.
>>>>>> - Odroid U3     - eMMC card insertion -> first boot from eMMC
>>>>>> - Odroid X2/XU3 - boot priority jumper
>>>>>>
>>>>>> By this commit, Exynos dwmmc driver will check the OM pin configuration,
>>>>>> and then try to init the boot device and register it as mmc 0.
>>>>>
>>>>> I think a better way to do this would be to make
>>>>> CONFIG_SYS_MMC_ENV_DEV support an option where the device can be
>>>>> selected at run-time.
>>>>>
>>>>> However that would probably be better done when the drive rmodel
>>>>> conversion is complete.
>>>>>
>>>>> So this seems a reasonable patch given where we are.
>>>>>
>>>>> Reviewed-by: Simon Glass <sjg at chromium.org>
>>>>>
>>>>
>>>> This was just a quick solution to solve the issue on XU3, when the
>>>> same binary can boot from sd or eMMC slots.
>>>
>>> XU3 isn't unique in this regard.  "am335x_evm" binaries runs on 4 very
>>> different boards and we still just have to say that sometimes we default
>>> to ENV in a place that isn't workable.
>>
>> Yes, I saw this issue on bb black. But it seems to be not a big
>> problem to fix it.
>> When I finish the pmic and finally start work on adding it to the bb
>> black, then maybe I will try to fix it somehow.
>
> It's not hard (extending some of the concepts we have already) but I
> want to hold that off until we have driver model support instead as part
> of a "carrot and stick" approach ;)
>

Ok, that's fine.

Regards,
-- 
Przemyslaw Marczak
Samsung R&D Institute Poland
Samsung Electronics
p.marczak at samsung.com