I've just bought a Toshiba Satellite L70-B-119. Windows 8 works OK on it. When running Linux, the screen has a serious problem with distortion and flickering lines. I've uploaded a video here:

http://copwick.net/private/IMG_0434.MOV

The video chip is this:

Intel Corporation Haswell-ULT DRAM Controller (rev 0b)

I have tried a variety of distributions, and each one has the same problem.

I tried getting newer Intel drivers from here:

https://01.org/linuxgraphics/downloa...er-linux-1.0.7

and installed them in both Fedora and Ubuntu (the only two distributions supported), but the problem persists.

I can get a steady screen by booting with the "nomodeset" kernel option, but this results in problems: the graphics look pretty ropey, I can't adjust the screen brightness, and the screen stays powered off following a suspend/resume cycle.

I have tried a number of other kernel options, as follows:

acpi_osi=Linux
acpi_backlight=vendor
i915.i915_enable_rc6=1

but none of these seem to make any difference.

I would be really grateful for any advice!

Thanks

Rob

Have a look in your firmware (BIOS) options and see if you can find an option for "Intel SpeedStep" -- this throttles down the graphics card for power-saving and reduces performance significantly.

Try disabling this option & see if it helps.

I can't view your video for some reason, so I may be way out on this...

It is very likely to be the Intel graphics drivers doing this. With 'nomodeset' you are forcing it to use the vesa drivers, which lack features but are stable.

So all the distributions you have tried are new, right ? I mean I'm thinking if this is a kernel bug it would be fixed in the newest kernels.

Head_on_a_Stick: thanks. The only thing that seems close is "Dynamic CPU Frequency Mode". This can be set to Dynamic Switch or Always Low. It doesn't seem to matter which it's on, the problem remains.

I have posted the video on Youtube, although the quality isn't good: http://youtu.be/IlVwkdjXfis

metaschima: Yes, I've tried mostly the newer distributions - the most recent kernel being (I think) the one in something called Tanglu, which is (again I think) 3.16.5. I also tried Fedora 21, Ubuntu 14.10, and some other recently released distributions. Also Fedora 20 and Ubuntu 14.04. Same thing in all of them.

One thing to try is make sure the horizontal and vertical refresh rates are what they should be. You can check in 'xrandr' or whatever GUI frontend your distro uses.

OK, thanks. I have tried setting some different refresh rates, but (apart from making my eyes hurt - or perhaps that's just because I've been staring at this screen for too long) it didn't affect the issue, as far as I could see.

It's been a few years since I felt the need to compile a kernel, but perhaps I should have a go with the latest version just in case ...

Phew, yes, that seems to have done the trick. I tried a 3.17 kernel first, but the issue was still present. However, with the latest stable kernel (3.18.1) it's gone away. Many thanks for your help.

So then it was the kernel Intel drivers.