[Intel-gfx] [BUG] i915 RC6 lockup

[Jonas Jelten]

Hi list!

I think i've got a problem with the intel driver:

Sometimes, I think especially after running graphics intense
applications, RC6 is disabled completely and heats up my Thinkpad X220t
to 90 degree celsius, while idling.

At first I thought that this is a CPU frequency scaling issue, as the
cpufreq_powersave claims to be running at 800 MHz, but i7z
(http://code.google.com/p/i7z/) shows all multipliers to be 25 -> 2.5
GHz CPU clock.

Powertop 2.1 reveals that the GPU is 100% active, 0% RC6, 0% RC6p and 0%
RC6pp, and the CPU is 99,9% in C7-deep-sleep, at maximum frequency.
/sys/kernel/debug/dri/0/i915_ring_freq_table also pointed the issue to
being caused by the GPU.

intel_gpu_top shows a total idle.

I'm on ArchLinux, Kernel 3.6.2, xf86-video-intel-git
b42d81b63f5b6a571faffaadd42c74adce40128a, this is 2.20.10.
Problem first occured with Kernel 3.6.0.
Core i5-2520M HD 3000

>cat /proc/cmdline
>cryptdevice=/dev/sda2:cryptroot root=/dev/mapper/cryptroot ro vga=791
>i915.i915_enable_rc6=7 i915.modeset=1 i915.lvds_downclock=1
>i915.semaphores=1 drm.vblankoffdelay=1 init=/bin/systemd
>initrd=../initramfs-linux.img BOOT_IMAGE=../vmlinuz-linux

Sometimes it can be fixed by going to pm-suspend and waking up. A reboot
always fixes it, until it randomly locks up the GPU again.

Please help me how i can do further investigation to catch the bug.

As this makes my Laptop consume ~40W, it would be really nice if this
gets fixed.


Cheers,

Jonas

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