Re: [BUG/REGRESSION] Screen flickering

[Thomas Gummerer <t.gummerer@gmail.com>]

Jan Niehusmann <jan@gondor.com> writes:

> Hi,
>
> On Wed, May 13, 2015 at 12:14:39PM +0300, Jani Nikula wrote:
>> Is this the same as https://bugzilla.kernel.org/show_bug.cgi?id=98141 ?
>
> The visible effect in the video is similar to what I see on the LVDS
> display. I also see some influence of the mouse pointer position on the
> blanked areas.

I can see the same thing, though it looks slightly different to me, but
the slight difference might be unrelated.

> The effect on the external screen is more like single scan
> lines jumping to the right and back, at a high (but still visible)
> frequency.

I don't see the behavior on my external screen.  Maybe some more
information that might help:

The laptop is a dell XPS 15 9530, screen resolution 3200x1800.  The
external display is connected via DisplayPort, resulution 1920x1080.
Output from lspci:

00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor DRAM Controller (rev 06)
00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor PCI Express x16 Controller (rev 06)
00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller (rev 06)
00:03.0 Audio device: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller (rev 06)
00:04.0 Signal processing controller: Intel Corporation Device 0c03 (rev 06)
00:14.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB xHCI (rev 05)
00:16.0 Communication controller: Intel Corporation 8 Series/C220 Series Chipset Family MEI Controller #1 (rev 04)
00:1a.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #2 (rev 05)
00:1b.0 Audio device: Intel Corporation 8 Series/C220 Series Chipset High Definition Audio Controller (rev 05)
00:1c.0 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #1 (rev d5)
00:1c.2 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #3 (rev d5)
00:1c.3 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #4 (rev d5)
00:1d.0 USB controller: Intel Corporation 8 Series/C220 Series Chipset Family USB EHCI #1 (rev 05)
00:1f.0 ISA bridge: Intel Corporation HM87 Express LPC Controller (rev 05)
00:1f.2 SATA controller: Intel Corporation 8 Series/C220 Series Chipset Family 6-port SATA Controller 1 [AHCI mode] (rev 05)
00:1f.3 SMBus: Intel Corporation 8 Series/C220 Series Chipset Family SMBus Controller (rev 05)
00:1f.6 Signal processing controller: Intel Corporation 8 Series Chipset Family Thermal Management Controller (rev 05)
02:00.0 3D controller: NVIDIA Corporation GK107M [GeForce GT 750M] (rev a1)
06:00.0 Network controller: Intel Corporation Wireless 7260 (rev 6b)
07:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5249 PCI Express Card Reader (rev 01)

> What I'm missing in the report, are some log entries I'm seeing on my
> notebook:
>
> Apr 30 08:50:23 localhost kernel: [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe B FIFO underrun
> Apr 30 08:50:23 localhost kernel: [drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder B FIFO underrun
> Apr 30 08:50:29 localhost kernel: [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun
> Apr 30 08:50:29 localhost kernel: [drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder A FIFO underrun

I see the last two messages in my dmesg output, but not the first two.

>
> Jan