Re: [3.14.0-rc4] regression: drm FIFO underruns

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, May 13, 2014 at 12:38:41PM +0200, Daniel Vetter wrote:
> On Tue, May 13, 2014 at 12:29 PM, Jörg Otte <jrg.otte@gmail.com> wrote:
> >>> Branch drm-intel-nightly as of
> >>> ed60c27 drm-intel-nightly: 2014y-05m-09d-21h-51m-45s integration manifest
> >>> looks badly:
> >>>    - KDE splash screen on boot-up is not visible
> >>>    - x-windows don't have title and menu bars
> >>>    - KDE system menu is not visible
> >>>    - moving windows around destroys its content
> >>
> >> Ugh, that's ugly. Nothing else change like e.g. the version of
> >> xfree-video-intel?
> >
> >  (II) Loading /usr/lib/xorg/modules/drivers/intel_drv.so
> >  (II) Module intel: vendor="X.Org Foundation"
> >  compiled for 1.11.3, module version = 2.17.0
> >  Module class: X.Org Video Driver
> >  ABI class: X.Org Video Driver, version 11.0
> 
> Chris, any ideas? It's an ivybridge apparently.
> 
> For the fifo underruns I think we've fully confirmed that they only
> happen on boot-up. I'll try to come up with some ideas what could have
> gone wrong there.

Please test the below patch.
-Daniel

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index b10fbde1d5ee..63ced2dee027 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -427,9 +427,6 @@ bool __intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
 
 	ret = !intel_crtc->cpu_fifo_underrun_disabled;
 
-	if (enable == ret)
-		goto done;
-
 	intel_crtc->cpu_fifo_underrun_disabled = !enable;
 
 	if (enable && (INTEL_INFO(dev)->gen < 5 || IS_VALLEYVIEW(dev)))
@@ -441,7 +438,6 @@ bool __intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
 	else if (IS_GEN8(dev))
 		broadwell_set_fifo_underrun_reporting(dev, pipe, enable);
 
-done:
 	return ret;
 }
 
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch