On 28 January 2015 at 16:23, Tobias Jakobi [off-list ref] wrote:

Ulf Hansson wrote:

quoted

On 28 January 2015 at 13:41, Tobias Jakobi [off-list ref] wrote:

quoted

Hello!

Jaehoon Chung wrote:

quoted

mmc core supported to hw_reset function.
So i think we can use it. It's called at only initial time to clear the previous status.
But i think it can be called at reboot time. (it needs to implement codes.)
how about?

I don't think that's going the work. The problem here is that depending
on the board configuration, the eMMC might carry the bootloader. If the
eMMC subsystem is not properly reset _during_ reboot, the board won't
even start since no bootloader is found. So we don't even reach the
point where the kernel does anything.

I guess it depends on what's being done during the reboot sequence.

The most proper thing would be to let the boot loader control the GPIO
to trigger the HW reset, but that would mean the boot loader need to
know about board specific configurations, such as which GPIO pin. So
maybe SOC vendors need to state what GPIO pin to use and don't leave
that as a configurable option.

Not the bootloader, but the iROM code would have to do this, and as far
as I know the iROM can't be modified. Or am I missing something here?

You are right! The "bootloader" can very likely be stored in ROM code.
That's why I also said the GPIO shouldn't be configurable. :-)

Kind regards
Uffe