4.13 (and probably all recent) kernels refuse to boot on one Nokia N950, work or another

Pavel Machek
2017-10-26T09:13:26Z

On Wed 2017-10-25 14:28:07, Tony Lindgren wrote:
> * Pavel Machek <pavel@ucw.cz> [171025 13:36]:
> > Hi!
> >
> > ...hardware should be identical. 3.5.3-nemo kernel seems to work on
> > both. 4.13-rc2 with display and clock patches boots on phone "S", but
> > does not on phone "P"; nothing nothing is received on serial port.
> >
> > There is some difference in the bootloaders: S's bootloader provides
> > lots of debug info, P's is silent. R&D settings do _not_ have
> > influence on bootloader. We know P's serial works, as 3.5.3 kernel
> > prints "Uncompressing linux...booting" there.
> >
> > I'll need to return "S" phone and serial cable tommorow. If you have
> > any ideas, let me know.
>
> If you get nothing out of the uart, chances are the pins are
> not muxed for the uart in nolo and maybe kernel dts is missing the
> pinctrl entries for uart?
>
> Also try booting with mem=512M at 0x80000000 or 256M or 768M. Maybe the
> memory is different size or partially broken?

Uhuh. It looks like "P" nokia really wants initrd, otherwise it will
not boot.

I got "uncompressing Linux 4.13" on serial console now, debug LEDs
blinking, and if I use a flashlight, I see output on the screen, too.

(What do I need to do to get the backlight working?)

Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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