Hi,

On Thu, Oct 26, 2017 at 11:13:26AM +0200, Pavel Machek wrote:

On Wed 2017-10-25 14:28:07, Tony Lindgren wrote:

quoted

* Pavel Machek [off-list ref] [171025 13:36]:

quoted

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?)

Glad you got it working :) For backlight you can add this
in drivers/gpu/drm/omapdrm/displays/panel-dsi-cm.c:

add the following code at the end of dsicm_probe:

-----------------------------------------------------------
mutex_unlock(&ddata->lock);
mutex_lock(&ddata->lock);
ddata->in->ops.dsi->bus_lock(ddata->in);
r = dsicm_wake_up(ddata);
if (!r)
    r = dsicm_dcs_write_1(ddata, DCS_BRIGHTNESS, 100);
ddata->in->ops.dsi->bus_unlock(ddata->in);
mutex_unlock(&ddata->lock);
-----------------------------------------------------------

-- Sebastian
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