[Letux-kernel] GTA04 display and 5.10-rc5

[H. Nikolaus Schaller]

Hi Andreas,

> Am 30.11.2020 um 09:23 schrieb Andreas Kemnade <andreas at kemnade.info>:
> 
> Hi,
> 
> I am wondering whether I am the only one. I get a white screen only.
> X11 detects the display but nothing is displayed. Seems to be a problem
> on mainline. letux3704 display works with the same userspace.

Well, I think I had tested it briefly and it was working, but I am not sure.

But - I now tried -rc6, -rc5, -rc4 and none is fully booting on the GTA04A5.

In most cases the GTA04A5 hangs after (once with a stack protector kernel panic):

[    3.104858] mmc0: new high speed SDHC card at address 59b4
[    3.112091] oprofile: using arm/armv7
[    3.117980] mmcblk0: mmc0:59b4 USDU1 29.8 GiB 
[    3.123107] ThumbEE CPU extension supported.
[    3.129333] Registering SWP/SWPB emulation handler

Strangely I also can no longer boot 5.9.10 nor 5.9.1. Only 5.4.79 did boot.
5.9.1 did boot well on the GTA04A4 after swapping the µSD into it... So it does
not depend on µSD content but hardware...

5.10-rc6 boots on the A4 but I also have a white display...
5.10-rc5 also has a white display on the A4...
5.10-rc4 panel works

So this makes it clear that it is the new omapdrm-mipi-dsi series which I
have started to integrate into letux-5.10-rc5.

This series seems to break drivers/gpu/drm/panel/panel-tpo-td028ttec1.c
while the Letux3704 uses one of the drivers/gpu/drm/panel/panel-simple.c
definitions. This explains why there is another difference between your
devices.

So something in Tomis series seems to break DPI with the specific driver.
The same may happen for VENC so we have to look at it as well.

And some other bug makes the GTA04A5 boot less reliable between 5.4 and 5.9.

The big question is what...

Have you tried upstream 5.10-rc5 with omap2plus_defconfig?

BR,
Nikolaus