Re: Dell Inspiron 14 Plus 5441 - keyboard backlight and panel (x1e80100 Thena)

[Val Packett <val@packett.cool>]

On 4/29/26 11:27 PM, Adam Szyma wrote:

> Hi Val,
>
> I have successfully installed Ubuntu 26.04 with kernel 7.0.0-32-qcom-x1e
> on a Dell Inspiron 14 Plus 5441 (x1e80100, codename Thena).
Hi, nice to hear that!
> The device uses the same x1-dell-thena.dtsi as the Inspiron 7441/Latitude 7455,
> but has two differences that need addressing:
>
> 1. KEYBOARD BACKLIGHT:
>     The dell-xps-ec driver (dell,xps13-9345-ec) is present in the kernel but
>     the DTS node for EC is missing from x1-dell-thena.dtsi.
>     Keyboard: hid-over-i2c, vendor 0x6243, i2c-4 (b80000.i2c), address 0x05.
>     Could you add the EC node to x1-dell-thena.dtsi to enable keyboard
>     backlight on this device?

Uhh, that driver is not merged upstream yet! -qcom-x1e is not linux-next :)

I'll definitely add the node when it gets merged.. or insist that Alex 
include it in the final version of the EC driver patch.

I'm surprised to hear it was necessary for keyboard backlight of all 
things. On my 7455, it was always controllable with the F5 key directly 
through the EC firmware, independently of the running OS. Funnily enough 
right now I have the driver loaded and that key stopped working so the 
driver might be breaking it a bit in some circumstances right now, heh.

> 2. DISPLAY PANEL:
>     The Inspiron 5441 uses a CSOT MPP36 T9 panel (CSW 0x143d, 1920x1200@60Hz)
>     instead of the panel in the 7441. Brightness control is non-functional.
>     I have already submitted a patch to dri-devel@lists.freedesktop.org:
>     Subject: [PATCH] drm/panel/panel-edp: Add CSOT MPP36 T9 eDP panel
>     Date: 2026-04-29, Message-ID: <20260429145251.8445-1-adamszyma@wp.pl>

I'm very surprised the entry was necessary for brightness of all things, 
are you sure that's not a coincidence? o.0 I haven't heard of delay 
timings impacting brightness control.

> Hardware info:
>     Model: Dell Inspiron 14 Plus 5441
>     SoC: Qualcomm X1E80100 (Snapdragon X Elite)

not the 80-100 :) I guess you have the 10-core cut-down Hamoa (64-100) 
variant, while there's also a Purwa (42-100) one.

>     Panel EDID: CSW 0x143d, MPP36 CSOT T9, 1920x1200@60Hz, 301x188mm

wow, I didn't realize they also used lower-resolution panels on the 
cheaper models.

~val