Created attachment 114294 [details]
I'm trying to get Linux to work on a Dell Venue 8 Pro 3845 tablet that comes preinstalled with Windows 8.1. I'm running Debian Testing (Jessie) installed via Steve McIntyre's 64-bit kernel on 32-bit UEFI Debian Installer images . If I go through the EFI boot menu, the device boots normally until X is started and the screen goes black, flashes briefly, and then stays black. If I prevent the intel X.org driver from loading by adding "nomodeset" to the kernel command line I can proceed to a working, albeit rather slow, Gnome session. This report is about getting accelerated graphics to work as well.
I noticed a number of Baytrail-related commits have gone into the kernel since 3.16.x which Jessie ships, so I've tried with a custom (yet unpatched) 4.0-rc2 build (and an unmodified Jessie user space).
The firmware is up to date (A02) and I should note that this is apparently not the same hardware as in earlier reports  which were for the model 3830 Venue 8 Pro.
I'm attaching the relevant configuration and log files. Xorg is started without an xorg.conf. There are two sets of logs one without and one with "drm.debug=0x06". The system crashed hard sometime after acquiring the first set.
The Xorg log does not contain errors. The kernel reports a "vblank wait timed out on crtc 0". One thing I noticed as somewhat odd is that xrandr lists the internal display (which AFAIK is connected via DSI) as "UNKNOWN1" rather than the "DSI1" which users of the 3830 model have reported but I don't know how significant that is. The internal display is the only display. There are no external connectors.
Let me know if I can provide any additional info or logs.
Created attachment 114295 [details]
dmesg output with default kernel command line
Created attachment 114296 [details]
Xorg.0.log with default kernel command line
Created attachment 114297 [details]
output of "xrandr --verbose" with default kernel command line
Created attachment 114298 [details]
dmesg output with drm.debug=0x06
Created attachment 114299 [details]
Xorg.0.log with drm.debug=0x06
Created attachment 114300 [details]
output of "xrandr --verbose" with drm.debug=0x06
Start by installing xf86-video-intel-2.99.917 (xserver-xorg-video-intel) and update the Xorg.0.log and xrandr --verbose.
Created attachment 114303 [details]
kernel log ("journalctl -k") with drm.debug=0x06 and xserver-xorg-video-intel-2.99.917
Created attachment 114304 [details]
Xorg.0.log with drm.debug=0x06 and xserver-xorg-video-intel-2.99.917
Created attachment 114305 [details]
output of "xrandr --verbose" with drm.debug=0x06 and xserver-xorg-video-intel-2.99.917
Thanks for the suggestion, Chris. I've installed xserver-xorg-video-intel from experimental now and updated the log attachments. I've also updated the kernel log as the previous attachment had been truncated.
Unfortunately, there is no visible change in behavior. xrandr, however, now lists the display as DSI1.
# dpkg -l xserver-xorg-video-intel
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
ii xserver-xorg-video-intel 2:2.99.917-1~exp1 amd64 X.Org X server -- Intel i8xx, i9xx display driver
(In reply to Rene Wagner from comment #11)
> Thanks for the suggestion, Chris. I've installed xserver-xorg-video-intel
> from experimental now and updated the log attachments. I've also updated the
> kernel log as the previous attachment had been truncated.
> Unfortunately, there is no visible change in behavior. xrandr, however, now
> lists the display as DSI1.
That and that the backlight is then detected was what I really wanted to check (in the ddx). I note that DSI *still* does not have the scaling modes exported.
(In reply to Chris Wilson from comment #12)
> That and that the backlight is then detected was what I really wanted to
> check (in the ddx). I note that DSI *still* does not have the scaling modes
Thanks again, Chris. Is there anything else I can do to help track this down?
Sounds like a dupe; we have some DSI work left to do.
*** This bug has been marked as a duplicate of bug 82880 ***