Dim screen after first boot on Thinkpad A285

Bug #1802834 reported by Bin Li
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux (Ubuntu)
Confirmed
Medium
Unassigned

Bug Description

We installed the 18.04 daily image on ThinkPad A285, found the screen is dim at the first boot.
---
ProblemType: Bug
ApportVersion: 2.20.9-0ubuntu7.4
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: u 1481 F.... pulseaudio
 /dev/snd/controlC0: u 1481 F.... pulseaudio
CurrentDesktop: ubuntu:GNOME
DistroRelease: Ubuntu 18.04
InstallationDate: Installed on 2018-11-12 (0 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
MachineType: LENOVO 20MWZ47RUS
Package: linux (not installed)
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-38-generic root=UUID=347498ab-8eae-42d3-a1e3-74e9be6b6ba3 ro quiet splash vt.handoff=1
ProcVersionSignature: Ubuntu 4.15.0-38.41-generic 4.15.18
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-38-generic N/A
 linux-backports-modules-4.15.0-38-generic N/A
 linux-firmware 1.173.1
Tags: bionic
Uname: Linux 4.15.0-38-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 09/21/2018
dmi.bios.vendor: LENOVO
dmi.bios.version: R0XET30W (1.07 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20MWZ47RUS
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrR0XET30W(1.07):bd09/21/2018:svnLENOVO:pn20MWZ47RUS:pvrThinkPadA285:rvnLENOVO:rn20MWZ47RUS:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad A285
dmi.product.name: 20MWZ47RUS
dmi.product.version: ThinkPad A285
dmi.sys.vendor: LENOVO

Revision history for this message
Bin Li (binli) wrote :

Here is the journalctl log.

Revision history for this message
Ubuntu Kernel Bot (ubuntu-kernel-bot) wrote : Missing required logs.

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1802834

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

Changed in linux (Ubuntu):
status: New → Incomplete
Revision history for this message
Bin Li (binli) wrote : AlsaInfo.txt

apport information

tags: added: apport-collected bionic
description: updated
Revision history for this message
Bin Li (binli) wrote : CRDA.txt

apport information

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Bin Li (binli) wrote : CurrentDmesg.txt

apport information

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Bin Li (binli) wrote : IwConfig.txt

apport information

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Bin Li (binli) wrote : Lspci.txt

apport information

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Bin Li (binli) wrote : Lsusb.txt

apport information

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Bin Li (binli) wrote : ProcCpuinfo.txt

apport information

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Bin Li (binli) wrote : ProcCpuinfoMinimal.txt

apport information

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Bin Li (binli) wrote : ProcEnviron.txt

apport information

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Bin Li (binli) wrote : ProcInterrupts.txt

apport information

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Bin Li (binli) wrote : ProcModules.txt

apport information

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Bin Li (binli) wrote : PulseList.txt

apport information

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Bin Li (binli) wrote : RfKill.txt

apport information

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Bin Li (binli) wrote : UdevDb.txt

apport information

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Bin Li (binli) wrote : WifiSyslog.txt

apport information

Changed in linux (Ubuntu):
status: Incomplete → New
Revision history for this message
Ubuntu Kernel Bot (ubuntu-kernel-bot) wrote : Status changed to Confirmed

This change was made by a bot.

Changed in linux (Ubuntu):
status: New → Confirmed
Revision history for this message
Joseph Salisbury (jsalisbury) wrote :

Does this issue still happen after applying the latest updates?

Would it be possible for you to test the proposed kernel and post back if it resolves this bug?
See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed.

Thank you in advance!

Changed in linux (Ubuntu):
importance: Undecided → Medium
Revision history for this message
Bin Li (binli) wrote :

Upgraded to 4.15.0-42 kernel from proposed. And this issue is still exist. And the default value is 12, but the max is 255.

$ cat /sys/class/backlight/amdgpu_bl0/brightness
12
$ cat /sys/class/backlight/amdgpu_bl0/max_brightness
255

Revision history for this message
Kai-Heng Feng (kaihengfeng) wrote :

Do you also see the issue on 19.04 daily image?

Revision history for this message
Bin Li (binli) wrote :

No, I didn't, let me try it.

Revision history for this message
Hui Wang (hui.wang) wrote :

 backlight_level = amdgpu_atombios_encoder_get_backlight_level_from_reg(adev);

 dig = amdgpu_encoder->enc_priv;
 dig->bl_dev = bd;

 bd->props.brightness = amdgpu_atombios_encoder_get_backlight_brightness(bd);
 bd->props.power = FB_BLANK_UNBLANK;
 backlight_update_status(bd);

 DRM_INFO("amdgpu atom DIG backlight initialized\n");

u8
amdgpu_atombios_encoder_get_backlight_level_from_reg(struct amdgpu_device *adev)
{
 u8 backlight_level;
 u32 bios_2_scratch;

 bios_2_scratch = RREG32(mmBIOS_SCRATCH_2);

 backlight_level = ((bios_2_scratch & ATOM_S2_CURRENT_BL_LEVEL_MASK) >>
      ATOM_S2_CURRENT_BL_LEVEL_SHIFT);

 return backlight_level;
}

Revision history for this message
Hui Wang (hui.wang) wrote :

So it looks like the initial brightness is got from atombios of graphic card, so it is atombios issue or the code can't correctly parse the atombios.

it is highly possible that this is an atombios issue.

Revision history for this message
Bin Li (binli) wrote :

After I resume from suspend, I found the backlight is normal, and here is the log.

Revision history for this message
Kai-Heng Feng (kaihengfeng) wrote :

When this issue happens, what's the output of "grep . /var/lib/systemd/backlight/*"?

Revision history for this message
Bin Li (binli) wrote :

After you install the 18.04 image, it will show the dim screen.
After suspend, the backlight is normal.

$ cat /var/lib/systemd/backlight/*
12

Revision history for this message
Bin Li (binli) wrote :

Installed the 19.04 daily image, the kernel is 4.18.0-11-generic. It works fine. And the brightness value is 255.

$ cat /sys/class/backlight/amdgpu_bl0/brightness
255
$ cat /sys/class/backlight/amdgpu_bl0/actual_brightness
255
$ cat /sys/class/backlight/amdgpu_bl0/max_brightness
255

Revision history for this message
Kai-Heng Feng (kaihengfeng) wrote :

This possibly means brightness value is 0 when systemd-backlight@amdgpu_bl0 saves the brightness, and it clamps its value to 5% of max_brightness which is 12.

Needs to perform a kernel bisection to find the fix commit.

Brad Figg (brad-figg)
tags: added: ubuntu-certified
tags: added: cscc
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