[U-Boot] [PATCH V2 6/6] arm: mx5: Add support for DENX M53EVK

[Stefano Babic]

On 21/04/2013 22:29, Marek Vasut wrote:
> Dear Benoît Thébaudeau,
> 
>> Dear Marek Vasut,
>>

Hi Marek,

>> On Sunday, April 21, 2013 9:12:31 PM, Marek Vasut wrote:
>>> Dear Benoît Thébaudeau,
>>>
>>>> Dear Marek Vasut,
>>>>
>>>> On Sunday, April 21, 2013 5:52:27 PM, Marek Vasut wrote:
>>>>> Add basic support for the DENX M53EVK board. Currently supported is:
>>>>> MMC (incl. booting)
>>>>>
>>>>              ^
>>>>
>>>> Can you clarify this, please?
>>>
>>> Use u-boot.imx for SD booting as usual.
>>>
>>>> spl_boot_device() points only to NAND, so
>>>> you're clearly talking about hardware MMC boot, and not about hardware
>>>> NAND boot followed by SPL payload fetched from MMC. But MMC boot does
>>>> not need SPL here, in which case you will have to generate a simple
>>>> u-boot.imx, or you will rather want to use u-boot-with-spl.imx for SD
>>>> (NAND header dropped to leave room for MBR). And in the latter case,
>>>> why have spl_boot_device() point to NAND for MMC boot?
>>>
>>> No, regular u-boot.imx will be used for SD boot.
>>
>> OK. So this will require to call make with u-boot.imx as the explicit
>> target. Should this be documented somewhere, perhaps in a README file for
>> this board?
>>
>> Another solution would be, like for woodburn, to have an sd-specific
>> config: - m53evk_nand_config would define CONFIG_SPL from boards.cfg, so
>>    u-boot-with-nand-spl.imx would be generated.
>>  - mx53evk_sd_config would not define CONFIG_SPL from boards.cfg, so
>> u-boot.imx would be generated.
>> And CONFIG_SPL would be removed from m53evk.h.
>>
>> Or, change the various config.mk in order to build u-boot.imx even if
>> CONFIG_SPL is defined, which would be useless for some boards, but useful
>> here in order to avoid having 2 configs for almost the same build, while
>> still not having to explicitly give a make target.
> 
> I'd love to see generic u-boot.nand , u-boot.sd etc. targets instead of these 
> CPU specific stuffs.
> 

But you forget that a single image can be saved on multiple storage:
u-boot.imx can be stored on SD or NOR or SPI-NOR, and that is the reason
for having SOC-specific extension.

I agree with Benoit: at the moment, only people working with i.MX know
that u-boot.im runs on SD. The third solution proposed by Benoit has the
drawback that probably not all boards need u-boot.imx (a board without
SD for example). At least we need an update of the README, but I think
it is not bad to have a new entry in boards.cfg.

Apart of that and not related to this patch, if we in future use SPL
also for booting from SD, we can get a single way to boot from different
storage. TI based SOCs already do this: same SPL, it checks from SD and
NAND.

Best regards,
Stefano

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