Re: [PATCH 3/4] drm/i915: enable VT switchless resume v3

Jesse Barnes
2014-05-20T21:10:22Z

On Tue, 20 May 2014 22:15:45 +0200
Daniel Vetter <daniel.vetter@ffwll.ch> wrote:

> On Tue, May 20, 2014 at 9:58 PM, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> > Ah, poll_enable is false until after _thaw finishes, so
> > our hotplug_resume call of hpd_irq_event does nothing. So aside from
> > the encoder hot_plug callbacks (which really just check dp link status,
> > which ought to be a no-op) our resume_hotplug function doesn't do
> > anything right now. May as well kill it and just send an unconditional
> > uevent?
>
> That's expensive since the reprobe will likely result in a few dropped
> frames (if the edid reading takes a long time). Better to do that in
> the kernel and avoid sending the uevent if nothing changed. Which iirc
> hpd_irq_event does for us.

Well delaying the resume by a long time isn't much better, but I guess
we need to fix this somehow.

Knut, does this patch also address your issue? It should reset the
connector status fields correctly so the X driver doesn't have to work
around things...

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index b948c71..e725235 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -623,8 +623,6 @@ static int __i915_drm_thaw(struct drm_device *dev, bool restore_gtt_mappings)
* */
intel_hpd_init(dev);
dev_priv->enable_hotplug_processing = true;
- /* Config may have changed between suspend and resume */
- intel_resume_hotplug(dev);
}

intel_opregion_init(dev);
@@ -694,6 +692,11 @@ int i915_resume(struct drm_device *dev)
return ret;

drm_kms_helper_poll_enable(dev);
+ if (drm_core_check_feature(dev, DRIVER_MODESET)) {
+ /* Config may have changed between suspend and resume */
+ intel_resume_hotplug(dev);
+ }
+
return 0;
}