[Bug 94605] [SKL] Flashing black screen ([drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=94605

--- Comment #98 from Paulo Zanoni <przanoni at gmail.com> ---
(In reply to Paulo Zanoni from comment #97)
> (In reply to Dominik Klementowski from comment #96)
> > (In reply to Paulo Zanoni from comment #94)
> > > (In reply to Dominik Klementowski from comment #92)
> > > > Latest intel-drm-nightly solved a lot of issues for my graphics - Intel HD
> > > > 520 (Skylake GT2) with Core i5-6200U (it's Acer E5 laptop). 
> > > > 
> > > > BOOT_IMAGE=/boot/vmlinuz-4.9.0-994-generic root=... ro i915.enable_rc6=0
> > > > quiet splash
> > > 
> > > Why are you using i915.enable_rc6=0? Please test again without that.
> > 
> > Ok, I can confirm now - without parameter i915.enable_rc6=0 flickering is
> > still present and pretty often (more than once per minute I guess).
> > I have todays' intel-drm-nightly kernel.
> > dmesg is clear. I only have some pcie errors
> 
> Wow. Can you please boot with drm.debug=0x1e i915.enable_rc6=1 and then
> retest, reproduce the problem, and attach the dmesg output here? (don't
> forget the drm.debug)

Please also use the log_buf_len=1M option in addition to the others.

> 
> Also, it would be good to know the exact model of your laptop. We're trying
> to find which machines have these flickering issues. Your dmesg says "Aspire
> E5-574", but it looks like there are multiple models for the E5-574 laptop,
> so I'd like to know the "full name" in case you have it.
> 
> Also, can you please do another test? Just "sudo mv /lib/firmware/i915
> /root/backup-lib-firmware-i915", then reboot and check if the problem
> persists.
> 
> All tests should be *without* the i915.enable_rc6=0 option.
> 
> Thanks,
> Paulo

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