Black screen with KABINI with kernel 4.5 with or without DAL

[Michel Dänzer]

On 05.04.2016 13:07, Boszormenyi Zoltan wrote:
> 2016-04-05 05:40 keltezéssel, Michel Dänzer írta:
>> On 05.04.2016 00:25, Boszormenyi Zoltan wrote:
>>>
>>> The application is Chromium in kiosk mode. The problem is that
>>> sometimes the screen stays black after KMS kicks in.
>> So the problem occurs even without X? Does it affect HDMI or
>> DisplayPort, or both?
> 
> It occurs on both but not without X. Ctrl-Alt-F2 gives me the
> console login prompt. My phrasing was not what I wanted to write
> and didn't finish the sentence really. X is started very early during
> boot so I can see the console message only momentarily while
> the screen is still in 80x25 VGA text mode. Restarting Xorg via
> systemctl makes it working most of the time.
> 
> Apparently, it's not Radeon specific. We were also able to reproduce
> it on an Intel machine, too, with internal LVDS and external VGA outputs.

I suspect it's a client side problem then. Comparing the good and bad
dmesg output shows that Xorg is busily updating the screen in the good
case (visible as radeon_crtc_page_flip gets called by TearFree) but not
so in the bad case. Since the default Xorg startup behaviour is a black
screen, it sounds like simply no client connects to Xorg / draws
anything to the screen in the bad case. Maybe there's a race which can
result in the client(s) starting up before Xorg, failing to establish
the display connection, or something like that.


> Is Xorg 1.16.4 still a supported version with new kernels?

There's no direct version inter-dependency between Xorg and the kernel.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer