[Bug 1813877] [NEW] Can't adjust brightness on DELL UHD dGPU AIO

Public bug reported:

[Impact]
The dell-uart-backlight driver has been loaded, but the backlight is controller by graphics driver instead of scalar IC. The old way to determinate weather the driver should be loaded is not working anymore, since the behavior of scalar command, show firmware version, is not the same as old platforms.

[Fix]
Using more a reliable command, get_scalar_status, to check if scalar is in charge of the AIO backlight.

[Test]
Verified on new Dell AIO platforms.

[Regression Potential]
Expected. The get_scalar_status command is not supported by the first generation AIO platforms, so the driver may not be loaded on old AIO machines due to get_scalar_status command returns 0. To ease the pain, the "force" parameter has been introduced to make the driver can be loaded regardless of the return value of get_scalar_status command.

** Affects: linux (Ubuntu)
Importance: Undecided
Assignee: AceLan Kao (acelankao)
Status: In Progress

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https://bugs.launchpad.net/bugs/1813877

Title:
Can't adjust brightness on DELL UHD dGPU AIO

Status in linux package in Ubuntu:
In Progress

Bug description:
[Impact]
The dell-uart-backlight driver has been loaded, but the backlight is controller by graphics driver instead of scalar IC. The old way to determinate weather the driver should be loaded is not working anymore, since the behavior of scalar command, show firmware version, is not the same as old platforms.

[Fix]
Using more a reliable command, get_scalar_status, to check if scalar is in charge of the AIO backlight.

[Test]
Verified on new Dell AIO platforms.

[Regression Potential]
Expected. The get_scalar_status command is not supported by the first generation AIO platforms, so the driver may not be loaded on old AIO machines due to get_scalar_status command returns 0. To ease the pain, the "force" parameter has been introduced to make the driver can be loaded regardless of the return value of get_scalar_status command.

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