Re: [BISECTED] drm: random hang since 620f378 "drm: prune modeswhen ..."

[Jesse Barnes]

On Mon, 14 Dec 2009 20:38:09 +0000
Arnd Bergmann <arnd@xxxxxxxx> wrote:

> On Monday 14 December 2009 18:20:15 Jesse Barnes wrote:
> > You can disable most of that code by loading i915 with
> > 'powersave=0'. If that patch really is at fault the powersave=0
> > should work around the issue as well.
> 
> Ok, I'll try that and let you know. Running the kernel before your
> patch has not crashed yet after two days of uptime. Now running
> with your patch but nothing else. When that crashes, I'll try
> the latest mainline with powersave=0.

Ok great.

> > It's been implicated in another issue (some display flicker and
> > underruns) so I'm pretty sure there's something wrong with it in
> > some configurations at least...
> 
> I haven't seen that yet. FWIW, the device in question is

[snip 4 series pci info]
 
> Let me know if you have a patch you want me to test.

This patch removes the suspect portion of the dynamic clock control
code.  Hopefully it'll be as stable as powersave=0 in your config
(assuming powersave=0 works :).

-- 
Jesse Barnes, Intel Open Source Technology Center

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_d
index 279dc96..b8730de 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3825,8 +3825,6 @@ void intel_decrease_renderclock(struct drm_device *dev)
                /* Down to minimum... */
                gcfgc &= ~GM45_GC_RENDER_CLOCK_MASK;
                gcfgc |= GM45_GC_RENDER_CLOCK_266_MHZ;
-
-               pci_write_config_word(dev->pdev, GCFGC, gcfgc);
        } else if (IS_I965G(dev)) {
                u16 gcfgc;
 
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