[Intel-gfx] Suggestions on fixing fill_modes ioctl() delays under i915

Eugeni Dodonov eugeni at dodonov.net
Mon Apr 16 15:33:43 CEST 2012

On Mon, Apr 16, 2012 at 09:04, Dan Aloni <alonid at gmail.com> wrote:

> Hello,
> I'd like to assist in fixing an issue that is quite nagging concerning the
> i915 driver. I wasn't sure whether to classify this as a bug, but it's
> something worth considering. Let me explain.
> When I first used the i915 driver on my Lenovo X220 laptop, I noticed that
> every time I run xrandr, or when any X client tries to query the display
> modes, the X server hangs for a second or so. Using systemtap, I was able
> to track the hang to the Intel DRM driver, around the area in which it
> talks over i2C in order to query the modes from display controller.

Could you try using the 3.4-rc1 or newer kernel by a chance? The patch that
I initially sent in past October which improves the i2c interaction for
output detection over 'phantom' outputs went in there, and so far it seems
to improve the display detection timing by 30%-3000% (depending on hardware
of course and number of outputs and such).

Eugeni Dodonov
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