Re: Porting barebox (devicetree) to Variscite iMX6 SOM

From: Sascha Hauer <s.hauer@pengutronix.de>
To: Michael Burkey <mdburkey@gmail.com>
Cc: barebox@lists.infradead.org
Subject: Re: Porting barebox (devicetree) to Variscite iMX6 SOM
Date: Fri, 10 Jan 2014 09:00:04 +0100	[thread overview]
Message-ID: <20140110080004.GS6750@pengutronix.de> (raw)
In-Reply-To: <CAJyuEefHk_D6U5Tkrf0CKVfRZ2VSxmfOE4TepG9G1yP9YvF24Q@mail.gmail.com>

On Thu, Jan 09, 2014 at 02:59:33PM -0500, Michael Burkey wrote:
> Sascha,
> 
> Since I am still having issues with the kernel booting -- and needed a
> bit of a break to clear my mind -- I decided to delve into the initial
> barebox bootup from NAND a bit more.
> 
> Correct me if I am wrong, but how I understand things right now...
> 
> The iMX6 requires a BCB header prior to the actual barebox partition
> (e.g. nand0.bootstream). This bootstream partition would contain the
> BCB data specific to the iMX6 (i.e. an FCB and at least a partial
> DBBT).

Yes, right.

> 
> It also looks like this functionality is already present in barebox
> for the MX23/28 series of parts (i.e. the "bcb" command).

Yes.

> 
> I also have the source for kobs-ng v1.3, which does properly generate
> the BCB for the MX6 series (and is what I am currently using to flash
> barebox into NAND).

Yes, kobs works for me aswell on i.MX6

> 
> So, basically, it sounds like what I need to do is migrate the bcb.c
> file from the arm/mach-mxs folder into the MX6 portion of the tree and
> then update it based on the datasheet and the "known good" parameters
> from kobs-ng v1.3 (which look fairly similar to the definitions you
> already have in place for the MX23/28 FCB).
> 
> Does this sound like a reasonable plan of action?

Indeed. I tried Doing that myself, but it didn't work, probably some
little piece was missing. I also started to port the original kobs code
to barebox, but was distracted. I can give you the code I have so far if
you like.

> 
> It really looks like life with the iMX6 would be much easier if I had
> a SPI-NOR on this SOM, instead of NAND only.

Yeah, indeed. I usually recommend our customers to not rely on NAND for
booting.

Sascha

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