Re: [PATCH] drm/i915: Fixup hpd irq register setup ordering

From: Daniel Vetter <daniel@ffwll.ch>
To: Imre Deak <imre.deak@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Subject: Re: [PATCH] drm/i915: Fixup hpd irq register setup ordering
Date: Tue, 11 Dec 2012 17:24:08 +0100	[thread overview]
Message-ID: <20121211162408.GT11556@phenom.ffwll.local> (raw)
In-Reply-To: <1355241528.1025.5.camel@localhost>

On Tue, Dec 11, 2012 at 05:58:48PM +0200, Imre Deak wrote:
> On Tue, 2012-12-11 at 14:05 +0100, Daniel Vetter wrote:
> > For GMCH platforms we set up the hpd irq registers in the irq
> > postinstall hook. But since we only enable the irq sources we actually
> > need in PORT_HOTPLUG_EN/STATUS, taking dev_priv->hotplug_supported_mask
> > into account, no hpd interrupt sources is enabled since
> > 
> > commit 52d7ecedac3f96fb562cb482c139015372728638
> > Author: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Date:   Sat Dec 1 21:03:22 2012 +0100
> > 
> >     drm/i915: reorder setup sequence to have irqs for output setup
> > 
> > Wrongly set-up interrupts also lead to broken hw-based load-detection
> > on at least GM45, resulting in ghost VGA/TV-out outputs.
> > 
> > To fix this, delay the hotplug register setup until after all outputs
> > are set up, by moving it into a new dev_priv->display.hpd_irq_callback.
> > We might also move the PCH_SPLIT platforms to such a setup eventually.
> > 
> > Another funny part is that we need to delay the fbdev initial config
> > probing until after the hpd regs are setup, for otherwise it'll detect
> > ghost outputs. But we can only enable the hpd interrupt handling
> > itself (and the output polling) _after_ that initial scan, due to
> > massive locking brain-damage in the fbdev setup code. Add a big
> > comment to explain this cute little dragon lair.
> > 
> > v2: Encapsulate all the fbdev handling by wrapping the move call into
> > intel_fbdev_initial_config in intel_fb.c. Requested by Chris Wilson.
> > 
> > v3: Applied bikeshed from Jesse Barnes.
> > 
> > v4: Imre Deak noticed that we also need to call intel_hpd_init after
> > the drm_irqinstall calls in the gpu reset and resume paths - otherwise
> > hotplug will be broken. Also improve the comment a bit about why
> > hpd_init needs to be called before we set up the initial fbdev config.
> > 
> > Bugzilla: Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=54943
> > Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> Looks ok:
> Reviewed-by: Imre Deak <imre.deak@intel.com>

Ok, patch merged again, thanks a lot for catching that resume/reset bug.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch