[SOLVED]ASUS C201PA Xorg support

[Wesman26]

Howdy Folks,

I recently got an ASUS C201PA and immediately installed Arch Linux ARM on
it, following the instructions for the C100P (flip) model since they share
the rockchip RK3288 and the Mali T764. So far my only problem is I can't get
X to start.
$this->bbcode_second_pass_code('', '[ 23.168] (WW) Falling back to old probe method for armsoc
[ 23.168] (II) No BusID or DriverName specified - opening /dev/dri/card0
[ 23.168] (EE) ERROR: Cannot set the DRM interface version.
[ 23.168] (EE) ERROR: Cannot open a connection with the DRM - Permission denied
[ 23.168] (EE) No devices detected.
[ 23.168] (EE)
Fatal server error:
[ 23.168] (EE) no screens found(EE)')

These lines seem to reveal the culprit: permissions. Has anyone else run
into these problems? Any good work arounds?

Thanks in advance,
Wes

Edit:
I downloaded xf86-video-armsoc-rockchip as well as veyron-libgl as per the advanced instructions, and I'm a member of the video group. Not sure where things are going wrong.

Solution:
Use lightdm (or any display manager from what I can tell). For some reason it can start X where xinit cannot.

[WarheadsSE]

Try using something like lightdm

[Wesman26]

No dice with LightDM. I installed and enabled it via systemctl, but when I
boot up it fails to start with journalctl giving me less than helpful
"Failed to start Light Display Manager." messages. Anything else that
might work?

[WarheadsSE]

Again, check the xorg logs

[Wesman26]

Both /var/log/Xorg.0.log and ~/.local/share/xorg/Xorg.0.log show no changes
and no mention of LightDM. Errors are the same as if I had used startx.

[WarheadsSE]

And what are the permissions of /dev/dri/card0 ?

[Wesman26]

Owner: root. Group: video. Read and Write for both.

[Wesman26]

So I feel mighty stupid, but I found the log files for lightdm in
/var/log/lightdm, where it was made clear to me that lightdm was failing to
start because I didn't have lightdm-gtk-greeter installed. At any rate, X
now starts through lightdm, but I'd really prefer to just use startx, and
forego the display manager; why does lightdm work when xinit doesn't? Is
there anything I can do to get it working?

As a sidenote: while X does seem to be working, my touchpad does not, any
ideas why that might be?

[moonman]

Google: archwiki touchpad

[Wesman26]

You know, sometimes I wonder where I was the day they handed out brains. Thanks for all your help and patience! I'm marking this one solved.