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

[Benoît Thébaudeau]

Hi Stefano,

On Wednesday, April 24, 2013 9:39:17 AM, Stefano Babic wrote:
> 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.

With this also comes the issue of BOOT_FROM in board/denx/m53evk/imximage.cfg.
Strictly speaking, in order to be correct, it should be #if-ed depending on some
config option: nand or sd.

Best regards,
Benoît