Blank LVDS panel on Intel IronLake laptop

[madmax]

Haiku R1/beta2 and nightly (playing with hrev54352) boot to a blank screen in my laptop with IronLake graphics. Not a hang, as it responds to long Ctrl-Alt-Supr, and the panel is on with backlight. It just doesn't display anything. Connecting a monitor to the VGA port doesn't change results.

What has worked for me is changing refclk_activate_ilk. There are three path selections there: Ibexpeak PCH, hasPanel and hasEDP. In my case, I have IBX and panel, and EDP is hardcoded as true for whatever reason. My results playing with that function are:

IBX	panel	EDP
Y	Y	Y	blank screen
Y	Y	N	blank screen
Y	N		blank screen
N	Y	Y	works
N	Y	N	works
N	N		works
return before changing anything			works

Where "works" means I get the desktop in the panel. The external VGA monitor doesn't get signal anyway, but there seems to be tickets for that already.

Syslogs attached, though the only relevant difference I see is "No changes to reference clock" in refclk_activate_ilk in the correct boot.

device Display controller (VGA compatible controller, VGA controller) [3|0|0]
  vendor 8086: Intel Corporation
  device 0046: Core Processor Integrated Graphics Controller

[pulkomandy]

For reference, proposed patch: ​https://review.haiku-os.org/c/haiku/+/3867

[madmax]

Fixed in hrev55052