linux-kernel - Re: [Intel-gfx] Interrupt latency on some 945GM platforms

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20100921155653.440afea4@jbarnes-desktop>
Date:	Tue, 21 Sep 2010 15:56:53 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Paolo Ornati <ornati@...il.com>
Cc:	Vasily Khoruzhick <anarsoul@...il.com>,
	Simon Farnsworth <simon.farnsworth@...lan.co.uk>,
	intel-gfx@...ts.freedesktop.org,
	Sitsofe Wheeler <sitsofe@...oo.com>,
	Venkatesh Pallipadi <venki@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [Intel-gfx] Interrupt latency on some 945GM platforms

On Tue, 21 Sep 2010 20:26:07 +0200
Paolo Ornati <ornati@...il.com> wrote:

> On Fri, 17 Sep 2010 15:50:43 +0300
> Vasily Khoruzhick <anarsoul@...il.com> wrote:
> 
> > > Vasily, can you try the qos workaround on your machine and see if it works
> > > too?
> > > 
> > > Thanks,  
> > 
> > Just give me a patch :)
> 
> Me too...
> 
> I've a laptop with 945GM (Asus x5dij) and with 2.6.32+ kernels I'm
> having random, but not frequent, screen flickering problems (for some
> reasons 2.6.31 works fine).
> 
> Problem goes away with "nohz=off".
> 
> I'll try with "processor.max_cstate=?" and see if that works too.

Can you guys try something like this?  My theory is that 945GM has some
power management behavior we're failing to configure correctly.  If
disabling it works, then it's likely related.

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_d
index 40cc5da..26e1d23 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5786,6 +5786,10 @@ void intel_init_clock_gating(struct drm_device *dev)
                                   I915_READ(MCHBAR_RENDER_STANDBY) & ~RCX_SW_EX
                }
        }
+
+
+       /* Disable power management on 945GM */
+       I915_WRITE(0x10f10, 0);
 }
 
 /* Set up chip specific display functions */


-- 
Jesse Barnes, Intel Open Source Technology Center
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/