Re: i915 suspend crash: BUG: unable to handle kernel NULL pointerdeferrence

From: Justin P. Mattock
Date: Fri Aug 12 2011 - 13:37:44 EST

on 08/12/2011 10:11 AM, Keith Packard wrote:
On Fri, 12 Aug 2011 08:57:41 -0700, "Justin P. Mattock"<justinmattock@xxxxxxxxx> wrote:

[ 96.384971] [drm:i915_get_vblank_timestamp] *ERROR* Invalid crtc 0

You're not using KMS are you...

UMS mode disables a ton of features in the driver; you've hit a couple
that weren't getting skipped in all cases.

Here's some patches that make sure two of the disabled features are
correctly bypassed. If these work for you, I'll create a couple of
patches, one per bug. Afterwards, you should really consider switching
to KMS...

(meanwhile, thanks for finding bugs in ancient code!)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 02f96fd..9cbb0cd 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2058,8 +2058,10 @@ void intel_irq_init(struct drm_device *dev)
dev->driver->get_vblank_counter = gm45_get_vblank_counter;

- dev->driver->get_vblank_timestamp = i915_get_vblank_timestamp;
+ if (drm_core_check_feature(dev, DRIVER_MODESET))
+ dev->driver->get_vblank_timestamp = i915_get_vblank_timestamp;
+ else
+ dev->driver->get_vblank_timestamp = NULL;
dev->driver->get_scanout_position = i915_get_crtc_scanoutpos;

if (IS_IVYBRIDGE(dev)) {
diff --git a/drivers/gpu/drm/i915/i915_suspend.c b/drivers/gpu/drm/i915/i915_suspend.c
index 87677d6..f107423 100644
--- a/drivers/gpu/drm/i915/i915_suspend.c
+++ b/drivers/gpu/drm/i915/i915_suspend.c
@@ -871,7 +871,8 @@ int i915_restore_state(struct drm_device *dev)

- intel_init_clock_gating(dev);
+ if (drm_core_check_feature(dev, DRIVER_MODESET))
+ intel_init_clock_gating(dev);

if (IS_IRONLAKE_M(dev)) {

I have: Enable modesetting on intel by default (DRM_I915_KMS) not set in my .config. I will enable that and see if this fixes this issue, if not then I will test those patches out.
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