From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michal Simek <monstr@monstr.eu>
Date: Tue, 10 Jul 2012 15:42:28 +0200
Subject: [U-Boot] FDT driver initialization function declaration
In-Reply-To: <201207101512.30389.marex@denx.de>
References: <4FFC02BD.7060106@monstr.eu> <4FFC1EF8.9060705@monstr.eu>
	<20120710130331.854362026C4@gemini.denx.de>
	<201207101512.30389.marex@denx.de>
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On 07/10/2012 03:12 PM, Marek Vasut wrote:
> Dear Wolfgang Denk,
>
>> Dear Michal Simek,
>>
>> In message<4FFC1EF8.9060705@monstr.eu>  you wrote:
>>> The hardest part I have identify on microblaze was about u-boot
>>> variables. Because based on information from device-tree you can choose
>>> where variables should be stored and also this memory should be
>>> accessible before u-boot try to read variables. It mean in very early
>>> state.
>>
>> Device initialization before relocation is already hard enough;
>
> +1
>
>> resources are very limited then.
>
> And we'll be introducing the early mallocator. This is where MPC85x will blow my
> mind :) (I'm repeating myself here, but it might help getting others unaware of
> the DM work better in line).
>
>> You will add the additional need to
>> have the FDT library available then, too.   Not to mention that you
>> need to load the DT blob, too.
>
> DT blob can be read from ROM if that was the problem. The DT library and parser
> might be an issue.
>
>> This will be a lot of added complexity.
>
> And therefore slowing down the boot. But I believe it can be optimized to
> leverage this to some point. Though I'm not quite sure how much. This is worthy
> investigation.
>
> Michal, can you try investigating how will the DT probing intertwine with the
> DM?

Firstly I need to understand what you are trying to achieve and how.
Then if I have time I can look at how DT probing can be added to it.

But I think that there is good example in the Linux kernel how to do it.
I believe that device-tree guys will have some good comments and
experiences from the kernel.

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian