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DDM, Linux, standard command to switch Preset Modes
Hello.
I am trying to get the ability to switch Preset Modes with ddcutil under linux.
In ddm.exe there is such a command for this purpose (described in readme):
SetNamedPreset [Movie/CAL1,etc] - changes the Preset mode*
Also, there is a generic control command there:
SetControl X Y - sets hex control X to hex value Y
Can you please tell how that SetNamedPreset may be invoked via a standard SetControl X Y commands?
In ddcutil/ddcui I can see 0xdc (Display Mode) control and it works normally (i.e. the monitor changes its brightness and color when I change a value). But it does not contain all modes that are in dell menu, it only contains this:
Feature: DC (Display Mode)
Values:
00: Standard/Default mode
02: Mixed
03: Movie
05: Games
(I think they are just standard for all monitors, but I may be wrong). Seems like ddm uses another feature that is 0xe2. This is from ddcutil capabilities scanning output for P2217H:
Feature: 0xe2 (Manufacturer Specific)
Values:
0x00: No lookup table
0x1d: No lookup table
0x01: No lookup table
0x02: No lookup table
0x04: No lookup table
0x0e: No lookup table
0x12: No lookup table
0x14: No lookup table
When I switch a Preset Mode manually via physical buttons on the monitor (they are called Standard, ComfortView, Multimedia, Movie, Game, Warm, Cool, Custom Color), and then read the value of that control (0xe2) with ddcutil getvcp, I can see that it changes:
VCP code 0xe2 (Manufacturer Specific): mh=0x00, ml=0xff, sh=0x00, sl=0x 1d
# ddcutil getvcp e2
VCP code 0xe2 (Manufacturer Specific): mh=0x00, ml=0xff, sh=0x00, sl=0x 01
But I am unable to change it via ddcutil setvcp:
Verification failed for feature e2
So when I know that, I could just do the same via ddcutil in linux.
Thanks.
DELL-Cares
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March 27th, 2021 06:00
We tried reaching you on a private message asking for the Dell PC and or Dell monitor Service Tag number to ascertain the warranty but did not receive a response. Please feel free to reply to the private message whenever you are available.
DELL-Cares
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April 4th, 2021 04:00
Hi AndrewShark, as this monitor model doesn't have the Linux as one of the tested OS we are unable to share the steps related to this. However, I will reach out to our product group team on this for further advise. Regarding this I will contact you via private message to collect few information.
AndrewShark
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April 4th, 2021 04:00
I have found the same request (to publish the non-standard dell mccs controls) from 2018 here:
https://www.dell.com/community/Monitors/U3818DW-Please-publish-the-VCP-MCCS-codes/td-p/6178993
It is sad that Dell do not cares (it seems) about sales of their products for Linux users. I personally very like the Dell monitors. But I would also like the functionality available with Dell Display Manager, speaking about auto switching Preset mode based on application in focus. Specifically, I want my monitor to automatically switch it when I do alt-tabbing from a game to the browser in which I read a walkthrough for the game (because reading text in Game preset really destroys my eyes, but playing a game in ComfortView preset is not beautiful).
I am not asking to create a Linux version of DDM. I am just asking for a documentation!
Linux desktop environments are different, and each may use their own window rules etc... But we do not need your windows-specific app to arrange windows on scren. We just need a cli for controlling their monitor, and then Linux users will be able to built the gui suitable for their wishes.
I have found several requests of dell display manager for linux:
https://askubuntu.com/questions/1171741/dell-display-manager
https://www.reddit.com/r/Ubuntu/comments/g6v0ao/dell_display_manager_on_ubuntu/
I cannot see any reason to keep it "in secret". There is no anything there that other manufacturers could benefit from. But you just loose the loyalty of linux users.
So please, if you care of your consumers, publish specifications. Linux power users can benefit from it by using your products productively. Dell will benefit from it because power users will purchase Dell monitors themselves and recommend it to other professionals.
To resolve this request, it just needs to reach the corresponding department inside dell. I mean, technical support do not know what to answer because they just search in published documentation for the product in the web site (sorry, I can do it myself, but there is no this info there, at least yet). But this request could be transferred to the Dell Display Manager application team (they for sure have this info, as they implemented a windows application) and/or hardware engineers that should have this info.
Any feedback from dell staff please?
swamped207
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April 4th, 2021 07:00
For the specific problem you mention, try this:
- to switch to Game preset, set VCPDC to 0x05
- to switch to ComfortView, set VCPF0 to 0x0C
Arrived at by following Dell advice in the thread you mention, comparing the before and after values reported by softMCCS on changing the Preset mode using the monitor OSD menu.