latitude e6420 screen flickering (sandy bridge intel video card)

[Manuel]

I just installed latest 11.04 release on my brand new dell e6420 latitude laptop and the screen flickers.

I don't know if it comes from kernel, driver or xserver.

It's a 1600x900 screen, I only have on board video card (sandy bridge arch).

Note: I installed ppa:xorg-edgers/ppa packages, while the flickering was reduced it's still present:
sudo apt-add-repository ppa:xorg-edgers/ppa
sudo apt-get update
sudo apt-get upgrade

[Manuel (manuel-vacelet)]

Actually it seems to be a HW related issue as moving the laptop in another office "solves" the flickering issue.

Though, the latest xorg-edgers packages broke the external VGA output, but it's not related to this issue.

[Frédéric Meynadier (frederic-meynadier-b)]

I experience a similar problem : 1600x900 screen, intel video, ubuntu 11.04, dell e6420 received 2 days ago, started flickering after waking up from a standby mode this afternoon.

Also a HW problem, as it happens also on the Win7 install that is installed alongside. In fact it flickers as soon as it lights up, from the earliest BIOS screen (several blinks per second). The external (DVI) display is OK.

Unfortunately this hasn't disappeared, so I had to call Dell support and they plan to replace the whole laptop display.

Could anybody confirm there is no way to damage any screen with the "standard" settings (I did not play with xrandr, for example). I remember the times when hacking the modeline in XF86Config was considered hazardous, back in the CRT days....
This time I just had to re-enter the "displays" parameters several times before reaching a functionning state, in the gnome-ish GUI that comes with Unity.

[Manuel (manuel-vacelet)]

I forgot to add my follow-up.

It's actually very strange. Here are my results:
* If I boot with nomodeset, there is no flickering but I cannot use any external display (my monitor appears in X.log but not seen by xrandr)
* If I boot without nomodeset (and with xorg-edgers ppa) with my external VGA monitor plugged, most of the time there is no flickering (at boot) but it does flickers (on laptop screen) after a standby.
* If I boot only on laptop (no external monitor), it does flicker all the time.

FInally, a cold boot on the morning on Win7 doesn't lead to flickering (either with or without external monitor plugged). But, if I get a flickering screen on Linux next reboot (or shutdown + cold boot within minutes) it impacts, bios, grub and Win7.

I ordered the very same laptop with Nvidia card, I will make the test in few days to see if I get the same issue.

[Frédéric Meynadier (frederic-meynadier-b)]

Follow up : the flicker lowered in intensity during the week end. It came back after the first stand-by mode.

I found that bug #761065 maybe somewhat related, but I'm not sure.

I just tried the proposed workaround, i.e. set /sys/module/i915/parameters/semaphores to "1", using the following kernel option in /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.semaphores=1"

(again, I suspect i915 is the correct module for sandy bridge HD 3000, but I'm not sure).

After running update-grub and rebooting, I still had flickering but the amplitude of the flicker is different depending on the screen zone (roughly 2/3 left : lower flicker, 1/3 right : same amplitude flicker).

Also there is a problem in the screen size calculation (part of my external monitor is duplicated on the laptop's screen) :

$ xrandr -q
Screen 0: minimum 320 x 200, current 3280 x 1080, maximum 8192 x 8192
LVDS1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 310mm x 174mm
   1600x900 60.0*+ 40.0
   1440x900 59.9
   1360x768 59.8 60.0
   1152x864 60.0
   1024x768 60.0
   800x600 60.3 56.2
   640x480 59.9
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 connected 1920x1080+1360+0 (normal left inverted right x axis y axis) 531mm x 298mm
   1920x1080 59.9*+
   1600x1200 60.0
   1680x1050 60.0
   1280x1024 60.0
   1440x900 59.9
   1280x960 60.0
   1280x800 59.8
   1024x768 60.0
   800x600 60.3 56.2
   640x480 60.0
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)

Screen has 3280 pixel width, where I should have 1600 + 1920 = 3520 pixels.... Looks like the driver thinks I have a 1360x768 laptop screen. .config/monitors.xml has the correct size (<width>1600</width><height>900</height>).

Weird...

[Frédéric Meynadier (frederic-meynadier-b)]

Oh, I forgot to mention : dmesg contains the following message (apparently provoked by switching from X mode to console, and vice-versa) :

[drm:drm_mode_getfb] *ERROR* invalid framebuffer id

If this is a kernel issue, here is mine :
Linux [hostname] 2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:24 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

[Frédéric Meynadier (frederic-meynadier-b)]

New follow-up : today,

$ xrandr
Screen 0: minimum 320 x 200, current 3520 x 1080, maximum 8192 x 8192
LVDS1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 310mm x 174mm
   1600x900 60.0 + 40.0*
[...]
HDMI3 connected 1920x1080+1600+0 (normal left inverted right x axis y axis) 531mm x 298mm
   1920x1080 59.9*+
[...]

The wrong refresh rate may explain the flickering on LVDS1 (but as I posted in #4, this is not always the case).

And when I boot without attached external monitor, 60.0 Hz is rightly selected, and flicker is less visible (but not absent).

Dell support comes today, I'll see if changing the screen does any good and report back.

[Frédéric Meynadier (frederic-meynadier-b)]

Dell has replaced the screen. No flicker any more but it is still quite difficult to set the resolutions (when setting the "desired" ones, ie 1600x1900 & 1920x1080) some parts of the screen remain black, and among this black parts some let the cursor visible (but only the cursor, i.e. dragging a window there leave the area black), and some don't even let the cursor appear.

[Manuel (manuel-vacelet)]

On my side I bought the very same laptop with Nvidia VM4200 card and everything works like a charm (resolution, external display, suspend to ram).
I remastered the Intel based laptop (the one that flickers) with Win7 only and it works like a charm on Win7 (no flickering at all).

I do believe there is a very poor support from Intel on Sandy Bridge based graphic chipset. Thankfully, Nvidia did a better job (sadly not Free :'()

[SuperSlug (brent-evans)]

I can confirm this bug is occurring on 11.04 Dell D6420 Intel Sandybridge Intel Video chipset.
It seems to occur when you try to user multiple monitors. Looks like it may be switching to 40 Hz refresh
rate even though xrandr reports it at 60 Hz. Using the latest from edgers/ppa.

There are also issues around configuration for multiscreen. The laptop screen will stay black after reboot.
Using a Dell 1920 X 1080 monitor. If there is more information I can provide, let know.

[Frédéric Meynadier (frederic-meynadier-b)]

OK, I finally made it work : using the GUI offered by unity, setting the resolutions I wanted, and not caring that the display was mangled when it asked me if the display was OK after setting the resolutions... I checked "yes" even if that was not true, so the config was saved (in .config/monitors.xml I presume). After a reboot everything was OK, even after one suspend-to-ram.

I had to edit monitors.xml and change "<primary> no </primary>" to "yes" on HDMI3 (corresponding to my external display), in order to have the launcher on my external screen.

One more possibly useful info : I used the read-edid package (and more precisely the 'get-edid| parse-edid' command) to get the vendor ID of my laptop's screens :

old one (broken) : SEC
new one (works until now !) : LGD

No idea what SEC stands for, but probably LGD stands for LG ?

[phitastic (robbel)]

SEC stands for Seiko Epson Corp. LGD for LG. I observe the same screen flicker with the SEC panel in my Lenovo T420s. I'll call to get the screen replaced, hopefully to a LG panel.

[phitastic (robbel)]

Actually, SEC appears to be Samsung in the T420s.

[Georg Grabler (ggrabler)]

For your information:
This bug exists obviously on more machines than one, but not on all Dell Latitude e6420 machines, but on some others.
I guess it has something to do with the video card installed, anyway, I already filed a bug report back in 3/2011.

Upstream bug:
https://bugs.freedesktop.org/show_bug.cgi?id=35812

I'm currently on trying to reproduce the error for Daniel Vetter on 3.5-rc4. If it is still reproducable, we will try to track down this bug.

Background:
In times pre-3.2, this happened during KMS.
It did not happen with kernel 3.2.8 (no clue why!).
I am not sure about 3.3, since I never used 3.3 (did stay with 3.2.8 - it worked).
Since 3.4 it happens (for me) only on X login, not at KMS stage!
What KMS and the X-Login (on KDE) have in common? A resolution change. KMS changes the screen resolution, KDM is displayed afterwrads (in a wrong resolution), and after login it does set the resolution to the chosen one, where I personally get stripes today.

I am not using ubuntu but chakra, so this is definitely no ubuntu issue, but an upstream one. I tried that with arch and fedora as well - same results.

The situation has gotten better, but it seems the bug we formerly had in the KMS is now in the X11 resolution change. Even though, I could not reproduce it (yet) changing resolution after I logged in successfully.

@Screen Flickering:
This is NOT an issue, the screen won't break! I have had it running having the stripes for a day(!), and ye, it did flicker a lot afterwards. If you leave your laptop alone, shut down, it will not flicker after a few hours of resting.

Since this bug got more attention now again by the intel guys (always very helpful and nice I gotta' say), I hope we can track it down for future kernel versions.

Hope this helps to accept the bug report and get it to [upstream]. Maybe some others are willing to help as well.

[Chris Wilson (ickle)]

6420 was one of the original eDP machines, it should be fully supported now.