[Bug 198885] New: amdgpu.dc=1 on CIK (R4 Mullins APU) brightness impossible to change. by Fn or "echo".

[Bug 198885] New: amdgpu.dc=1 on CIK (R4 Mullins APU) brightness impossible to change. by Fn or "echo".

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=198885

            Bug ID: 198885
           Summary: amdgpu.dc=1 on CIK (R4 Mullins APU) brightness
                    impossible to change. by Fn or "echo".
           Product: Drivers
           Version: 2.5
    Kernel Version: 4.15.4
          Hardware: x86-64
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: high
          Priority: P1
         Component: Video(DRI - non Intel)
          Assignee: drivers_video-dri@kernel-bugs.osdl.org
          Reporter: soprwa@gmail.com
        Regression: No

Created attachment 274359
  --> https://bugzilla.kernel.org/attachment.cgi?id=274359&action=edit
dmesg with "amdgpu.dc=1"

I am using gentoo ~amd64, kernel 4.15.4, amdgpu with amdgpu.dc=1 on CIK A6 APU
- R4 Mullins.

There is no possibility to change brightness level both with Fn keys or
directly by an "echo" command, even as root when "amdgpu.dc=1" is set:

ls -l /sys/class/backlight/amdgpu_bl0/
razem 0
-r--r--r-- 1 root root 4096 02-22 13:41 actual_brightness
-rw-r--r-- 1 root root 4096 02-22 13:41 bl_power
-rw-r--r-- 1 root root 4096 02-22 13:41 brightness
lrwxrwxrwx 1 root root    0 02-22 13:41 device -> ../../../0000:00:01.0
-r--r--r-- 1 root root 4096 02-22 13:40 max_brightness
drwxr-xr-x 2 root root    0 02-22 13:41 power
lrwxrwxrwx 1 root root    0 02-22 13:40 subsystem ->
../../../../../class/backlight
-r--r--r-- 1 root root 4096 02-22 13:40 type
-rw-r--r-- 1 root root 4096 02-22 13:39 uevent


"/sys/class/backlight/amdgpu_bl0 # echo 22 > actual_brightness
bash: actual_brightness: permission denied"

and 

"/sys/class/backlight/amdgpu_bl0 # echo 128 > brightness
bash: echo: błąd zapisu: Bad argument"

Without "amdgpu.dc=1" in kernel command line changing brightness level is
working as expected, both Fn keys, and echoing directly to a file.

I know that there are plans enabling amdgpu.dc by default, so impossibility to
change brightness level IMHO is a big "no go".

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[Bug 198885] amdgpu.dc=1 on CIK (R4 Mullins APU) brightness impossible to change. by Fn or "echo".

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=198885

Michel Dänzer (michel@daenzer.net) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |harry.wentland@amd.com

--- Comment #1 from Michel Dänzer (michel@daenzer.net) ---
(In reply to Przemek from comment #0)
> -r--r--r-- 1 root root 4096 02-22 13:41 actual_brightness
[...]
> "/sys/class/backlight/amdgpu_bl0 # echo 22 > actual_brightness
> bash: actual_brightness: permission denied"

As you can see above, this file is read-only.


> "/sys/class/backlight/amdgpu_bl0 # echo 128 > brightness
> bash: echo: błąd zapisu: Bad argument"

What does

 cat max_brightness

say? If it's a value smaller than 128, does writing a value <= that to the
brightness file work?


> Without "amdgpu.dc=1" in kernel command line changing brightness level is
> working as expected, both Fn keys, and echoing directly to a file.

What values do the brightness, max_brightness and actual_brightness files
contain in that case?

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[Bug 198885] amdgpu.dc=1 on CIK (R4 Mullins APU) brightness impossible to change. by Fn or "echo".

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=198885

--- Comment #2 from Przemek (soprwa@gmail.com) ---
Hi Michel,

Thank you very much for insane-fast response.

Yes, "actual_brightness" is a bad example, same occurs on this file without
"amdgpu.dc=1".

Here are values from requested files:

"/sys/class/backlight/amdgpu_bl0 # cat brightness
3" 

"/sys/class/backlight/amdgpu_bl0 # cat max_brightness
255"

"/sys/class/backlight/amdgpu_bl0 # cat actual_brightness
3"

I have tried different values also:
"/sys/class/backlight/amdgpu_bl0 # echo 100 > brightness
bash: echo: błąd zapisu: Bad argument
/sys/class/backlight/amdgpu_bl0 # echo 50 > brightness
bash: echo: błąd zapisu: Bad argument
/sys/class/backlight/amdgpu_bl0 # echo 10 > brightness
bash: echo: błąd zapisu: Bad argument"

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[Bug 198885] amdgpu.dc=1 on CIK (R4 Mullins APU) brightness impossible to change. by Fn or "echo".

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=198885

--- Comment #3 from Przemek (soprwa@gmail.com) ---
And here values from requested files without "amdgpu.dc=1"

"/sys/class/backlight/amdgpu_bl0 # ls -l
razem 0
-r--r--r-- 1 root root 4096 02-22 17:50 actual_brightness
-rw-r--r-- 1 root root 4096 02-22 17:50 bl_power
-rw-r--r-- 1 root root 4096 02-22 17:39 brightness
lrwxrwxrwx 1 root root    0 02-22 17:50 device -> ../../card0-eDP-1
-r--r--r-- 1 root root 4096 02-22 17:39 max_brightness
drwxr-xr-x 2 root root    0 02-22 17:50 power
lrwxrwxrwx 1 root root    0 02-22 17:39 subsystem ->
../../../../../../../class/backlight
-r--r--r-- 1 root root 4096 02-22 17:39 type
-rw-r--r-- 1 root root 4096 02-22 17:38 uevent"

"/sys/class/backlight/amdgpu_bl0 # cat brightness
23"

"/sys/class/backlight/amdgpu_bl0 # cat actual_brightness
23"

"/sys/class/backlight/amdgpu_bl0 # cat max_brightness
255"


With smaller values from previous post (with "amdgpu.dc=1" on kernel
commandline) screen is much brighter, as backlight was set almost 100%.

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[Bug 198885] amdgpu.dc=1 on CIK (R4 Mullins APU) brightness impossible to change. by Fn or "echo".

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=198885

--- Comment #4 from Harry Wentland (harry.wentland@amd.com) ---
Thanks for reporting this. It's currently not hooked up for ASICs older than
Carrizo. We'll take a look. 

You're right that it clashes with the kernel's 'no regressions' policy should
we change pre-VEGA ASIC support with DC to enabled by default.

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[Bug 198885] amdgpu.dc=1 on CIK (R4 Mullins APU) brightness impossible to change. by Fn or "echo".

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=198885

--- Comment #5 from Przemek (soprwa@gmail.com) ---
(In reply to Harry Wentland from comment #4)
> Thanks for reporting this. It's currently not hooked up for ASICs older than
> Carrizo. We'll take a look. 
> 
> You're right that it clashes with the kernel's 'no regressions' policy
> should we change pre-VEGA ASIC support with DC to enabled by default.

Hi Harry,

I am glad to hear that the reason is already known, and we are not searching it
blindly.

There is still time till 4.17 merge window ends, so if you would like me to try
out some patches, please do not hesitate.

Thanks,
Przemek.

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[Bug 198885] amdgpu.dc=1 on CIK (R4 Mullins APU) brightness impossible to change. by Fn or "echo".

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=198885

--- Comment #6 from Harry Wentland (harry.wentland@amd.com) ---
Can you try the drm-next-4.17-wip branch from
https://cgit.freedesktop.org/~agd5f/linux? This should be fixed there.

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[Bug 198885] amdgpu.dc=1 on CIK (R4 Mullins APU) brightness impossible to change. by Fn or "echo".

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=198885

Przemek (soprwa@gmail.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |CODE_FIX

--- Comment #7 from Przemek (soprwa@gmail.com) ---
Sorry for the delay but I had to git clone whole agd5f branch repo once again
since I was moving my installation to another drive.

Moreover I had kernel panic with PSP platform module turned on
(CONFIG_CRYPTO_DEV_SP_PSP), but it is not the case of this bug report. (BTW as
from the specs this apu has one included).

Brightness keys are working as expected,
/sys/class/backlight/amdgpu_bl0/brightness is now editable by "echo", Display
Core is initialized with v3.1.40, so I am closing this bug report as
solved/code fix.

Thank you very much for fast and accurate action on this. Done to a turn.

Thanks once again,
Przemek.

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