Re: 2.6.32.1 i915 KMS rmmod failure

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Wed, 16 Dec 2009 20:08:16 +0100
Krzysztof Halasa <khc@pm.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