Re: [git pull] drm for v4.8

[Linus Torvalds]

On Mon, Aug 1, 2016 at 9:32 PM, Dave Airlie <airlied@xxxxxxxx> wrote:
>
> This is the main drm pull request for 4.8, I'm down with a cold at the moment
> so hopefully this isn't in too bad a state, I finished pulling stuff last
> week mostly (nouveau fixes just went in today), so only this message should
> be influenced by illness. Apologies to anyone who's major feature I missed :-)
>
> i915:
>         BXT support enabled by default
>         GVT-g infrastructure
>         GuC command submission and fixes
>         BXT workarounds
>         SKL/BKL workarounds
>         Demidlayering device registration
>         Thundering herd fixes
>         Missing pci ids
>         Atomic updates

Hmm. I did the merge and pushed it out, but testing it on my laptop
shows some very annoying flickering problem.

The screen goes dark for a very short while (one frame? Who knows?
Seems longer occasionally). I have no idea what triggers it, but it
happens quite a lot when it happens. Like once every second or two.
And it seems to happen most of the time, although right now it happens
to be behaving nicely, so sometimes it goes for a while without the
flickering.

Things *work*, but the flickering is nasty enough to make the end
result painful to use.

The only thing I see in dmesg that looks bad is

   [drm:intel_set_cpu_fifo_underrun_reporting [i915]] *ERROR*
uncleared fifo underrun on pipe A
   [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A
FIFO underrun

but I've seen that before, and it happens a couple of times during
boot. Not once per second.

This is my old Vaio 11 Pro, now running Fedora 24 (up-to-date as of today).

So it's bog-standard intel graphics (i5-4200U - Haswell ULT).

Suggestions to try?

             Linus