Hello Michael,
On Wed, Oct 30, 2013 at 6:35 PM, Michael Trimarchi michael@amarulasolutions.com wrote:
On Wed, Oct 30, 2013 at 9:11 PM, Wolfgang Denk wd@denx.de wrote:
Dear Michael Trimarchi,
In message CAOf5uw=hCkwPaqogCO3KvM1erhS-dvC5BRT4USU3uqKETtTQ7A@mail.gmail.com you wrote:
This does not answer Stefano's question: why do it in SPL, what's wrong with loading the real U-Boot for this purpose?
Because it's not possible, internal memory size of some cpus. You need to have a way to load the second stage and I'm discussing a general way to do.
I'm not sure that there are many use cases where you have sufficient room for all that is needed for DFU (including I/O buffers); and if you move to RAM early, you have other options as well.
No because you need anyway to have a way to load it and dfu is a way.
What is your alternative way?
Depending on your hardware there is a zillion ways to do this. For low to medium volumes good old JTAG is still a very powerful tool; for high volumes you will probably just fit pre-programmed NAND on your board. And of course there is the growing number of systems that can just boot and install from a SDCard or USB MSD.
I accept the lesson even I don't thing that I need a lesson on it. We are talking that we have only otg.
I see your user-case and I think I agree with you.
BTW Forget about it.
Please don't. I think it is a valuable contribution and I think it is good to have a mechanism which work for your user-case in U-Boot; it is easy to maintain long term and avoid duplication of work in case users has some problem.
I got a little bit lost when Tom gave an example where he 'loads' MLO and U-Boot image from OTG; just clarify it for me as it is not clear if it works for you or does not.
From what I understand, your use-case would be:
OTG -> SPL -> DFU -> U-Boot Image -> Jump to U-Boot ?