[BUG]: can't change brightness settings on XYC Q8

[kiselev-mikhail]

Version

2.0.0 (Dev_build) nigthly

Version type

uClibc (compatible)

Version hash

Issue description

Can't change screen brightness on XYC Q8.

Steps to reproduce

1. Turn the device ON.
2. a. Press either "VOL + →" or "VOL + ←".
3. b. Or go to the settings menu, change brightness value and save settings.
4. Brightness level stays the same.

What device are you using?

XYC Q8

Relevant log outputs

Issues' terms

• I did not find any existing open/closed issue of same matter

[Apaczer]

Could you try to replace this suniv-f1c100s-miyoo.dtb file (unzip & backup the old-one) in your BOOT partition and see if there is improvement? This DTB file is for CFW you've been using or older, not the latest one.

We believe the brightness levels should be lower on your XYC device.

[kiselev-mikhail]

Just to be on a saner side,
the Version 2.0.0 Beta (Pre-Release)*
had been flashed on the XYC's microSD,
the system was initialized,
and the suniv-f1c100s-miyoo.dtb file was unziped
and placed instead of the existing one in the BOOT partition.

Sadly, there's no improvement.

* - brigtness levels can't be changed on neither beta pre-release, nor nightly builds

[Apaczer]

Does the NULL values disables backlight? e.g. when in suspend mode, is the screen turned-off not backlit?

[kiselev-mikhail]

Whilst in the suspend mode there's no backlight (and no picture for that matter).

---

On that note, I've just tried to lower the brightness levels way down,
only to find out there is actually an improvement:

• 20 and up will give a uniform brightness
• 10 will be slightly less bright

(Tested with the updated suniv-f1c100s-miyoo.dtb present.)

[kiselev-mikhail]

I've decompiled the DTBs,
the one that comes with the Version 2.0.0 Beta 2
and the one that you've provided
into DTS files.

Most prominently, you've changed brightness-levels values from

<0x00 0x0a 0x14 0x1e 0x28 0x32 0x3c 0x46 0x50 0x5a 0x64>

to

<0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a>

i.e.

0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100

to

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

It seems, in practice,
XYC Q8 will have a uniform brightness for values 2 (0x02) and higher;
its screen will shine less brightly upon receiving a backlight value of 1 (0x01).

So, is it a sound idea to feed the backlight-levels fractional hex numbers?
And generally, how safe is it to pass different values to the brightness-levels?

---

A bit of background:
I am not particularly afraid of a GNU/Linux command line, though I'm quite cautious and conservative around hardware hacking for the time being,
i.e. I don't want to fry or damage a computer hardware in question, if it can be helped :)

[Apaczer]

kernel creates uint32-array table from steps provided in brightness-levels (see in src: Documentation/devicetree/bindings/leds/backlight/pwm-backlight.yaml). I was told that removing leading trailing 0 fixed the issue in another XYC device. Since this is rather range problem, try with this DTS:
suniv-f1c100s-miyoo.zip
(sha256 4039652f797fdf9ca3fc556bc7318426b5ef5bd838d093a6db655eb8551a3653)

NOTE: this is for latest nightly build, not sure if this will work on older

[kiselev-mikhail]

The spiked brightness-levels

brightness-levels = <0x00 0x01 0x03 0x05 0x08 0x0a 0x0c 0x0f 0x12 0x14 0x64>

in the suniv-f1c100s-miyoo.zip
(sha256 4039652f797fdf9ca3fc556bc7318426b5ef5bd838d093a6db655eb8551a3653)
introduce an interesting behavior to the mix:

10-40  will turn the screen completely off
50-70  will uniformly give a less bright screen
80-100 are uniformly about a more bright screen

Checked on the latest nightly build.