[Letux-kernel] jz4780 read out LCDC setup for HDMI

H. Nikolaus Schaller hns at goldelico.com
Thu Jun 4 17:18:09 CEST 2020


Hi Paul,

> Am 04.06.2020 um 12:50 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> Hi Paul,
> picking up an old discussion,
> 
>> Am 11.03.2020 um 14:30 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>> 
>>> How did you read them?
>> 
>> I used devmem2 (may be an omap tool I have recompiled for MIPS - it uses /dev/mem).
>> 
>>> Do it from the regmap: should be "cat /sys/kernel/debug/regmap/13050000.lcd-controller/registers" (not sure about the path)
>> 
>> Well seems to give the same result:
>> 
>> root at letux:~# cat /sys/kernel/debug/regmap/13050000.lcd-controller/registers
>> 00: 00000000
>> 04: 00000000
>> 08: 00000000
>> 0c: 00000000
>> 10: 00000000
>> 14: 00000000
>> 18: 00000000
>> 1c: 00000000
>> 20: 00000000
>> 24: 00000000
>> 28: 00000000
>> 2c: 00000000
>> 30: 00000000
>> 34: 00000000
>> 38: 00000000
>> 3c: 00000000
>> 40: 00000000
>> 44: 00000000
>> 48: 00000000
>> 4c: 00000000
>> 50: 00000000
>> 54: 00000000
>> 58: 00000000
>> 5c: 00000000
>> root at letux:~# 

now it becomes interesting.

I have booted the latest letux-5.7 and now, the lcdc got initialized!
So maybe something has improved in the DRM subsystem without our activity.

root at letux:~# cat /sys/kernel/debug/regmap/13050000.lcdc0/registers 
00: 00f00840
04: 00000003
08: 0000000d
0c: 0520026e
10: 011b051b
14: 0014026c
18: 00000000
1c: 00000000
20: 00000000
24: 00000000
28: 00000000
2c: 00000000
30: 24002008
34: 00000004
38: 00000000
3c: 00000000
40: 0e2ee000
44: 01000000
48: deafbead
4c: 00096000
50: 0007626f
54: 01050010
58: 2d544d47
5c: 00000032
root at letux:~# 

Still there is no image.

> 
> I did now boot with the Imagination system in Flash memory.
> It is an 3.0.8-Kernel. And my HDMI monitor works out of the box.

I did boot with both kernel and did run my scripts (using devmem2)
on both devices. The register values of each kernel are attached.

Main difference for the PHY seems to be in the audio area, but there
are also some HDMI_IH, HDMI_VP and HDMI_FC registers where I don't
have any idea what they are about.

As mentioned above the LCDC has been initialized (without me
recognising this first). But register values are completely different.

BR,
Nikolaus

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