Bug 153181

Summary:	[drm:ironlake_crtc_compute_clock [i915]] ERROR Couldn't find PLL settings for mode!
Product:	Drivers	Reporter:	Robin Müller (rm1990)
Component:	Video(Other)	Assignee:	drivers_video-other
Status:	RESOLVED INVALID
Severity:	normal	CC:	a-kobel, oceans112
Priority:	P1
Hardware:	Intel
OS:	Linux
Kernel Version:	4.7	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	dmesg Xorg.log (native modesetting)

Description Robin Müller 2016-08-15 20:58:10 UTC

After upgrading to linux-4.7 I get the following error during boot time and while starting Wayland or xserver (ends in a black screen):

[drm:ironlake_crtc_compute_clock [i915]] *ERROR* Couldn't find PLL settings for mode!

I'm not sure if this is the cause for the error but I had a look to the changes of the intel_driver.c between 4.6 and 4.7 and noticed the following:
With linux-4.6 the method ironlake_crtc_compute_clock used ironlake_compute_clocks for retrieving the PLL settings. Which then used on of the following methods depending on the given device:
- g4x_find_best_dpll
- chv_find_best_dpll
- vlv_find_best_dpll
- pnv_find_best_dpll
- i9xx_find_best_dpll
In linux-4.7 the method ironlake_crtc_compute_clock uses only this one g4x_find_best_dpll.

Comment 1 Alexander Kobel 2016-08-15 23:41:09 UTC

Confirmed on a Samsung NP900X4C laptop (Intel HD graphics 4000) on Arch Linux. Worked fine in 4.6.5. A discussion with some (unsuccessful) hints is here: https://bbs.archlinux.org/viewtopic.php?id=215847

Things that didn't work:
- uninstall xf86-video-intel and use the native modesetting
- add iomem.relaxed

Comment 2 Alexander Kobel 2016-08-15 23:41:53 UTC

Created attachment 228961 [details]
dmesg

Comment 3 Alexander Kobel 2016-08-15 23:46:29 UTC

The error message is also shown with each virtual console switch. Trying to start X as root locks up my machine (Magic SysRq works, nothing else); as normal user, X fails to start, but leaves me in control otherwise. Attaching Xorg.log too; if you need other logs, let me know.

Comment 4 Alexander Kobel 2016-08-15 23:48:15 UTC

Created attachment 228971 [details]
Xorg.log (native modesetting)

Comment 5 Jani Nikula 2016-08-16 11:35:52 UTC

Please file new drm/i915 bugs at https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel

Comment 6 Alexander Kobel 2016-08-16 11:59:24 UTC

Thanks for the info.

Moved to https://bugs.freedesktop.org/show_bug.cgi?id=97363