On 1 March 2017 at 04:36, Michael Mrozek <EvilDragon@openpandora.org> wrote:

Am Tue, 28 Feb 2017 20:14:45 +0100 hat Matthijs van Duin
<matthijsvanduin@gmail.com> geschrieben:

Hi,

> > I already had observed that there is some "memory effect" which has
> > something to do with how fast and in which sequence power is
> > (re)applied and so far I thought that the Palmas backup (supercap)
> > has something to do with it.
> Ah there's a supercap too? I hadn't even stopped to think about that
> one..
> I've quite often seen strange memory effects, or "bistability" of
> some sort where it either boots fine (into u-boot at least)
> repeatedly, or utterly fails (often even without any message on
> console) repeatedly.

Hm, that's very weird and we should try to find out what happens here.

I agree. I've been working on getting the early debug console for SPL working (u-boot's equivalent to earlycon) so we can get console output at any time. It's not working yet, but I'm fairly sure I know why so I'll give that another try.

Linux earlycon seems to work with:

CONFIG_SERIAL_EARLYCON=y

CONFIG_SERIAL_8250=y

CONFIG_SERIAL_8250_CONSOLE=y

CONFIG_SERIAL_8250_OMAP=y

CONFIG_SERIAL_8250_OMAP_TTYO_FIXUP=y

CONFIG_SERIAL_OF_PLATFORM=y

# CONFIG_SERIAL_OMAP is not set

CONFIG_DEBUG_LL=y

CONFIG_DEBUG_OMAP2PLUS_UART=y

CONFIG_DEBUG_OMAP4UART3=y

CONFIG_EARLY_PRINTK=y

It doesn't really sound like a hardware instability issue if the
hardware works fine once you managed to boot it up.

No, I really have no idea yet what's going on there, or which stateful components are involved (since problems even seem to be somewhat persistent across power cycling by long-pressing the power button).

Note that I'm also however suffering from plain instability, I've never been able to run Linux for very long.

I wonder if there are some parameters set that freeze the system and
that aren't resetted properly...?

There are plenty of settings that aren't reset at all, but they also shouldn't have to be reset in the first place. They should simply be configured correctly.

What does the Shoulder-Button + Power Button do?

It asserts nRESWARM of omap5 and of palmas, and resets eMMC. This seems correct to me.

The reset should ALWAYS work, especially when the system crashes or
freezes. If the OMAP / PALMAS freezes and ignores the reset signal,
then that's not really useful :)

They definitely don't (and can't) ignore it. I don't really have an explanation yet why this degree of reset doesn't always resolve crashes, but as I said I'm even experiencing problems that seem to persist across power cycling.

Note that although warm reset doesn't reset *everything*, this is generally a good thing. For example a warm reset allows the system to determine what caused the reset, and in principle it should be possible to perform JTAG debugging across a warm reset. A cold reset doesn't allow either of these.

Matthijs