Re: Eyestrain problems with new Intel drivers

* Eyestrain problems with new Intel drivers
@ 2014-01-09 23:30 Michael Vanier
  0 siblings, 0 replies; 5+ messages in thread
From: Michael Vanier @ 2014-01-09 23:30 UTC (permalink / raw)
  To: intel-gfx

Hi everyone,

I recently got a new Macbook Pro, which I dual-booted into Ubuntu 13.10 
(Linux kernel 3.11).  My previous computers were from 2008 and used ATI 
or Nvidia graphics cards.  The new one (with Intel HD 4000 integrated 
graphics, core i7, no other graphics card) seems to cause me a lot of 
eyestrain compared to what I'm used to. The experience I have is that 
light surfaces appear to shimmer in a way that didn't used to happen, 
and this shimmering seems to be related to the eyestrain.  After about 
an hour I really don't want to use the computer anymore; it's like a 
burning/sore feeling in the eyes coupled with dry eyes.  It's not a 
monitor problem, because I can hook up the Macbook to an old monitor 
which works perfectly well with old hardware (no eyestrain) and the 
eyestrain is still there. So it would appear to be due to the graphics 
hardware/driver combination.  It's also not Intel-specific or 
OS-specific; I've seen the same effect on Mac OS X and using different 
video cards; it seems to be the new normal.  I'm really confused about 
what could be causing this.  Resolutions don't matter; you always get 
the eyestrain.  My first thought was temporal dithering (or 
spatiotemporal dithering), but my reading of the intel driver source is 
that the kernel drivers have disabled ST dithering in favor of spatial 
dithering.  I have seen a few people report similar problems in mailing 
lists (including this one), and some of them got some relief by 
disabling the DRI/DRI2 extension in Xorg (this was around 2010), which 
doesn't seem to do much for me (nor does switching to the modesetting 
driver or fbdev driver). (Interestingly, using modesetting/fbdev drivers 
doesn't seem to slow down glxgears either, which always claims to run 
around 1700 FPS).  Some people got relief by switching to the Vesa 
driver, which my Xorg won't accept; it just unloads it and reloads the 
Intel driver.  Interestingly, the eyestrain is present even before X 
loads up or if you don't load X at all; when the system boots you can 
see very flat-looking text (which I think is OK) and then it switches to 
a more shimmering kind of text (presumably when the intel driver kicks 
in).  You would think plain text would have absolutely constant pixel 
values, but that isn't what I see (except on old hardware).

I'm sure that 99% of people can't notice this, but for the 1% who can 
it's a huge pain.  I'm on another mailing list with dozens of other 
people with similar problems, so it isn't just me.  If anyone has any 
suggestions as to what I/we can try (not eyedrops, I mean software 
stuff) or where I can look, I'd be really grateful.  I've had my eyes 
checked recently and they're fine.

Thanks!

Mike

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