[Intel-gfx] drm/i915: Agressive downclocking on Baytrail

[Chris Wilson]

On Wed, Jan 06, 2016 at 11:17:20AM -0800, Jesse Barnes wrote:
> On 01/06/2016 11:15 AM, Janne Heikkinen wrote:
> > I've got Bay Trail based Asus X553MA and I've been experiencing daily hangs
> > with kernels beginning from 4.2-rc1. I haven't had any problems with 4.1.x
> > kernels and using 4.1.13 I've gotten constant 5+ day uptimes since November
> > (I had to at least suspend it once per week for traveling but during Christmas
> > longest uptime was 11 days).
> > 
> > Now I did bisection beginning with marking 4.2-rc1 as bad and 4.1.0 as good
> > and found out that it was this commit:
> > 
> > [8fb55197e64d5988ec57b54e973daeea72c3f2ff]
> > drm/i915: Agressive downclocking on Baytrail
> > 
> > causing the hangs.
> > 
> > 4.4-rc8 hanged in less than hour. After I reversed the patch from it and
> > commented out lines containing related fields from i915_debugfs.c
> > I now seem to have stable 4.4-rc8.
> 
> Cc'ing Deepak and Chris.

It's the c0 w/a reads that got reintroduced. Why those vlv_punit_read()
result in a machine hang was never understood.

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index b407058076ab..3c31a219545f 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -4412,7 +4412,7 @@ void intel_irq_init(struct drm_i915_private *dev_priv)
        INIT_WORK(&dev_priv->l3_parity.error_work, ivybridge_parity_work);
 
        /* Let's track the enabled rps events */
-       if (IS_VALLEYVIEW(dev_priv))
+       if (IS_VALLEYVIEW(dev_priv) && 0)
                /* WaGsvRC0ResidencyMethod:vlv */
                dev_priv->pm_rps_events = GEN6_PM_RP_DOWN_EI_EXPIRED | GEN6_PM_RP_UP_EI_EXPIRED;
        else
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre