From b236d7c8421969ac0693fc571e47ee5c2a62fb90 Mon Sep 17 00:00:00 2001 From: Lyude Date: Tue, 21 Jun 2016 17:03:43 -0400 Subject: drm/i915/vlv: Disable HPD in valleyview_crt_detect_hotplug() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit One of the things preventing us from using polling is the fact that calling valleyview_crt_detect_hotplug() when there's a VGA cable connected results in sending another hotplug. With polling enabled when HPD is disabled, this results in a scenario like this: - We enable power wells and reset the ADPA - output_poll_exec does force probe on VGA, triggering a hpd - HPD handler waits for poll to unlock dev->mode_config.mutex - output_poll_exec shuts off the ADPA, unlocks dev->mode_config.mutex - HPD handler runs, resets ADPA and brings us back to the start This results in an endless irq storm getting sent from the ADPA whenever a VGA connector gets detected in the middle of polling. Somewhat based off of the "drm/i915: Disable CRT HPD around force trigger" patch Ville Syrjälä sent a while back Cc: stable@vger.kernel.org Cc: Ville Syrjälä Signed-off-by: Lyude Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_crt.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'drivers/gpu/drm/i915/intel_crt.c') diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c index d172930ac1e7..827b6ef4e9ae 100644 --- a/drivers/gpu/drm/i915/intel_crt.c +++ b/drivers/gpu/drm/i915/intel_crt.c @@ -329,10 +329,25 @@ static bool valleyview_crt_detect_hotplug(struct drm_connector *connector) struct drm_device *dev = connector->dev; struct intel_crt *crt = intel_attached_crt(connector); struct drm_i915_private *dev_priv = to_i915(dev); + bool reenable_hpd; u32 adpa; bool ret; u32 save_adpa; + /* + * Doing a force trigger causes a hpd interrupt to get sent, which can + * get us stuck in a loop if we're polling: + * - We enable power wells and reset the ADPA + * - output_poll_exec does force probe on VGA, triggering a hpd + * - HPD handler waits for poll to unlock dev->mode_config.mutex + * - output_poll_exec shuts off the ADPA, unlocks + * dev->mode_config.mutex + * - HPD handler runs, resets ADPA and brings us back to the start + * + * Just disable HPD interrupts here to prevent this + */ + reenable_hpd = intel_hpd_disable(dev_priv, crt->base.hpd_pin); + save_adpa = adpa = I915_READ(crt->adpa_reg); DRM_DEBUG_KMS("trigger hotplug detect cycle: adpa=0x%x\n", adpa); @@ -357,6 +372,9 @@ static bool valleyview_crt_detect_hotplug(struct drm_connector *connector) DRM_DEBUG_KMS("valleyview hotplug adpa=0x%x, result %d\n", adpa, ret); + if (reenable_hpd) + intel_hpd_enable(dev_priv, crt->base.hpd_pin); + return ret; } -- cgit v1.2.3