[Bug 42960] Display does not work when resuming from suspend

https://bugs.freedesktop.org/show_bug.cgi?id=42960

--- Comment #34 from D djtm@gmx.net --- (In reply to comment #32)

I tested with 3.15-git , and it looks like the kernel parameter has no effect there - the same problem occurs again! Even with acpi_sleep=s3_bios , on suspend and resume the laptop LVDS display is blank.

Does anyone know if this was an intentional change, to remove the ability to do this?

Hi, did you check using echo mem > /sys/power/state?

Because e.g. pm-suspend resets those parameters via /proc/sys/kernel/acpi_video_flags. (Value should be 1, 2, or 3 if you have kernel parameters set)

For pm-suspend to work (e.g. *Ubuntu) you need to create a file /etc/pm/config.d/radeon which contains QUIRK_S3_BIOS="true" QUIRK_S3_MODE="true"