[Intel-gfx] [PATCH v4 1/2] drm/i915: Protect fbdev across slow or failed initialisation

[Joonas Lahtinen]

On to, 2016-03-31 at 17:13 +0100, Chris Wilson wrote:
> On Thu, Mar 31, 2016 at 07:05:21PM +0300, Joonas Lahtinen wrote:
> > 
> > On to, 2016-03-31 at 14:57 +0100, Chris Wilson wrote:
> > > 
> > >  void intel_fbdev_restore_mode(struct drm_device *dev)
> > >  {
> > > -	int ret;
> > > -	struct drm_i915_private *dev_priv = dev->dev_private;
> > > -	struct intel_fbdev *ifbdev = dev_priv->fbdev;
> > > -	struct drm_fb_helper *fb_helper;
> > > +	struct intel_fbdev *ifbdev = intel_fbdev_get_if_active(dev);
> > >  
> > > -	async_synchronize_full();
> > What's with the async_synchronize_full() begin removed completely?
> Because it's not just wrong, but completely broken imo.
> 
> During suspend, we want to freeze the async task not flush. Then here
> and during resume we skip the restoration of the unregistered fbdev, and
> then when the task is woken it can complete the registration and present
> the vanilla ifbdev.
> 
> During hibernation, we really just want to cancel the task and start
> from scratch on resume.

Maybe Ack from Lukas with those? As this is effectively a revert of :

	commit a7442b93cf32c1e1ddb721a26cd1f92302e2a222
	Author: Lukas Wunner <lukas at wunner.de>
	Date:   Wed Mar 9 12:52:53 2016 +0100

	    drm/i915: Fix races on fbdev

Committed without R-b by Daniel, so maybe he has a comment on it too.

Regards, Joonas

> -Chris
> 
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation