[Intel-gfx] [PATCH 1/3] drm/i915: don't block resume on fb console resume

[Jesse Barnes]

On Mon, 15 Oct 2012 12:32:05 +1000
Dave Airlie <airlied at gmail.com> wrote:

> > The console lock can be contended, so rather than prevent other drivers
> > after us from being held up, queue the console suspend into the global
> > work queue that can happen anytime.  I've measured this to take around
> > 200ms on my T420.  Combined with the ring freq/turbo change, we should
> > save almost 1/2 a second on resume.
> 
> Did you measure booting with quiet? I can't think what else could be
> contending on this lock other than printk, now maybe we should reduce
> the printk noise!
> 
> This will make debugging things even worse than they are, since you
> don't see any printks on the screen until after we do this.

I thought I measured with quiet, but I'll double check.

Not sure about debugging; it's pretty bad to begin with.  I generally
use netconsole or the "stare really hard at the code" method when it
comes to suspend/resume or init time anyway.

But yeah, some investigation into the console lock contention is
probably a good idea at any rate.  A typical distro config probably
also has some other fbcon driver and probably vgacon built-in too, and
I haven't checked what they do.

Jesse