[Intel-gfx] [PATCH 0/7] drm/i915: Disable hpd for disabled eDP ports

[Ville Syrjälä]

On Mon, Jan 12, 2015 at 04:46:12PM -0800, Sean V Kelley wrote:
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> On 01/09/2015 04:21 AM, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > My BSW has a nasty problem where it generates tons of spurious hpd
> > interrupts when the eDP display is disabled. The best solution
> > seems to be to disable hpd for eDP ports when the port is disabled
> > since we don't care about long hpds anyway and short hpds are only
> > relevant while the link is up and running.
> > 
> 
> How did these spurious interrupts affect your system?

You get tons of debug spew from the kernel. In fact occasionally so much
that there's a feedback loop where the debug prints cause more noise on
the hpd line to generate more spurious interrupts. It could become bad
enoguh that the machine was pretty much dead, just constantly printing
hpd debug messages.

> Did you see this on both B and C Stepping?

Yep. It's probably more or a board issue.

> 
> Sean
> 
> 
> 
> > This series tries to implement that, and I've included a few
> > random fixes/refactorings to the hpd code as well.
> > 
> > Ville Syrjälä (7): drm/i915: Make hpd arrays big enough to avoid
> > out of bounds access drm/i915: Remove I915_HAS_HOTPLUG() check from
> > i915_hpd_irq_setup() drm/i915: Don't register HDMI connectors for
> > eDP ports on VLV/CHV drm/i915: Don't pretend SDVO hotplug works on
> > 915 drm/i915: Set intel_connector->polled to DRM_CONNECTOR_POLL_HPD
> > when appropriate drm/i915: Unify hpd setup between init and hpd
> > storm handling drm/i915: Disable HPD for disabled eDP ports
> > 
> > drivers/gpu/drm/i915/i915_irq.c      | 172
> > ++++++++++++++++++++--------------- 
> > drivers/gpu/drm/i915/intel_crt.c     |   4 +- 
> > drivers/gpu/drm/i915/intel_display.c |   6 +- 
> > drivers/gpu/drm/i915/intel_dp.c      |  18 ++++ 
> > drivers/gpu/drm/i915/intel_dp_mst.c  |   2 + 
> > drivers/gpu/drm/i915/intel_drv.h     |   3 + 
> > drivers/gpu/drm/i915/intel_hdmi.c    |   2 + 
> > drivers/gpu/drm/i915/intel_sdvo.c    |   4 + 8 files changed, 136
> > insertions(+), 75 deletions(-)
> > 
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-- 
Ville Syrjälä
Intel OTC