[Intel-gfx] [BUG] i915 RC6 lockup

[Jonas Jelten]

On 10/17/2012 04:30 AM, Ben Widawsky wrote:
> On Tue, 16 Oct 2012 15:19:26 +0200
> Jonas Jelten <jelten at in.tum.de> wrote:
> 
>> 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.
> 
> Do you mean the GPU is 0% active? If you really mean 100% then the
> results are expected, though I'm not sure how powertop attempts to
> calculate the GPU activity. I'm guessing it's just 100 - rc6
> state percentage, which when rc6 works is probably pretty close to
> reasonable.
> 
>>
>> intel_gpu_top shows a total idle.
> 
> This indicates the above assumption is true.
> 
>>
>> 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
> 
> Obviously a bisect of the exact failing commit would be fantastic.
> 
>>
>>> 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
> 
> First and most obvious, do not set rc6=7. If you do, do not file
> bug reports with those results. RC6++ is known to be extremely broken,
> and why we let users so easily hurt themselves is probably something we
> need to remedy. On HD3000, even rc6+ is highly recommended against.
> 
>>
>> 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.
> 
> If you can reproduce it with rc6=1, then it echoes some other bugs
> we're trying to track down. Figuring out the most minimal test case to
> make it occur would be helpful. Also you can search the mailing list
> for RPS related patches which seem to be related. Trying some of those
> and reporting your results would be helpful.
> 
> Double check your dmesg for any GPU hangs which may have occurred before
> the laptop becomes a space heater.
> 
> 
>>
>> As this makes my Laptop consume ~40W, it would be really nice if this
>> gets fixed.
>>
>>
>> Cheers,
>>
>> Jonas
>>
>>
> 

others are also suffering:

https://bugs.archlinux.org/task/32025

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