linux-kernel - Re: 2.6.32.1 i915 KMS rmmod failure

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Message-ID: <20091216115103.042aacdf@jbarnes-piketon>
Date:	Wed, 16 Dec 2009 11:51:03 -0800
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Krzysztof Halasa <khc@...waw.pl>
Cc:	Zhenyu Wang <zhenyuw@...ux.intel.com>,
	Nanhai Zou <nanhai.zou@...el.com>,
	lkml <linux-kernel@...r.kernel.org>,
	dri-devel@...ts.sourceforge.net
Subject: Re: 2.6.32.1 i915 KMS rmmod failure

On Wed, 16 Dec 2009 20:08:16 +0100
Krzysztof Halasa <khc@...waw.pl> wrote:

> Hi,
> 
> The following sequence causes the machine to hang hard:
> modprobe drm debug=65535
> modprobe i915 modeset=1
> rmmod i915
> 
> Linux 2.6.32.1 x86-64, i915 (the machine is a slimline MSI Hetis 915
> barebone), 2 GB RAM etc. Kernel messages captured with a serial
> console. Only analog VGA output connected (no EDID, using a "pro" 5 *
> BNC cable to connect to an old analog monitor). There is
> (unconnected) digital DVI and a TV encoder. Other details available
> on request.
> 
> The IRQ happens in intel_pipe_set_base()
> 
> 	DRM_DEBUG("Writing base %08lX %08lX %d %d\n", Start, Offset,
> x, y); I915_WRITE(dspstride, crtc->fb->pitch);
> 	if (IS_I965G(dev)) {
>         	...
> 	} else {
> 		I915_WRITE(dspbase, Start + Offset);
> 		I915_READ(dspbase);
>   >>>>>>> IRQ seems to be triggered at this point <<<<<<<
> 	}
> 
> Any ideas?

Seems like we should be disabling everything at unload time rather than
trying to set a new mode... If the dspbase we program isn't mapped
anymore we'd definitely get into trouble.

-- 
Jesse Barnes, Intel Open Source Technology Center
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