Re: [PATCH] ARM: dts: am33xx: Move the cppi41dma node so it's probed early

[Sebastian Andrzej Siewior <bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>]

On 04/22/2014 04:19 PM, Ezequiel Garcia wrote:
> The DMA controller is needed for the USB controller to be correctly
> registered. Therefore, if the DMA node is located at the end an unecessary
> probe deferral is produced systematically.
> 
> This is easily fixed by moving the node at the beggining of the child list,
> so it's probed first.

So you do not change anything except for the order of child nodes. So
this should be fine and without a compatibility problem.

I added them according to the memory offset so you might want to add a
comment why you moved this because Mr. Structured & Organized might
noticed this one day and move it back.

> Signed-off-by: Ezequiel Garcia <ezequiel-30ULvvUtt6G51wMPkGsGjgyUoB5FGQPZ@public.gmane.org>
> ---
> Felipe, Sebastian:
> 
> I cannot see why the cppi41dma node must be placed inside the
> "ti,am33xx-usb" compatible node. Tried to move it out
> so it's probed just like the edma engine, but the USB doesn't work
> properly in that case.
> 
> Can you enlighten me?

So If I remember correctly it was a big bag of crap. If you look at the
parent node, you notice that it has a ti,hwmods member while the other
do not have such a property. According to the manual only the whole IP
block as-it has this. It has to be activated if you use one of those
devices this includes the two USB-IP cores and the DMA-IP core. I
didn't manage to come up with something else except to make one parent
node which creates the childs to have a proper relation here.

There was also something with parent - child relation in the way musb
expected it. I think this was only glue code + musb child node and had
nothing to do with the DMA engine. But I am not 100% sure…

> 
> In any case, this change is good enough to remove the deferral probe.

Sebastian
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