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From: Egbert Eich <eich@suse.de>
To: intel-gfx@lists.freedesktop.org
Cc: Egbert Eich <eich@suse.de>, Daniel Vetter <daniel.vetter@ffwll.ch>
Subject: [PATCH 4/4] drm/i915: Avoid race of intel_crt_detect_hotplug() with HPD interrupt
Date: Tue,  1 Sep 2015 22:21:35 +0200	[thread overview]
Message-ID: <1441138895-23732-5-git-send-email-eich@suse.de> (raw)
In-Reply-To: <1441138895-23732-1-git-send-email-eich@suse.de>

A HPD interrupt may fire during intel_crt_detect_hotplug() - especially
when HPD interrupt storms occur.
Since the interrupt handler changes the enabled interrupt lines when it
detects a storm this races with intel_crt_detect_hotplug().
To avoid this, shiled the rmw cycles with IRQ save spinlocks.

Signed-off-by: Egbert Eich <eich@suse.de>
---
 drivers/gpu/drm/i915/intel_crt.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index af5e43b..685f3de 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -376,9 +376,10 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
 {
 	struct drm_device *dev = connector->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 hotplug_en, orig, stat;
+	u32 hotplug_en, stat;
 	bool ret = false;
 	int i, tries = 0;
+	unsigned long irqflags;
 
 	if (HAS_PCH_SPLIT(dev))
 		return intel_ironlake_crt_detect_hotplug(connector);
@@ -395,12 +396,14 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
 		tries = 2;
 	else
 		tries = 1;
-	hotplug_en = orig = I915_READ(PORT_HOTPLUG_EN);
-	hotplug_en |= CRT_HOTPLUG_FORCE_DETECT;
 
 	for (i = 0; i < tries ; i++) {
 		/* turn on the FORCE_DETECT */
-		I915_WRITE(PORT_HOTPLUG_EN, hotplug_en);
+		spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+		hotplug_en = I915_READ(PORT_HOTPLUG_EN);
+		I915_WRITE(PORT_HOTPLUG_EN, hotplug_en |
+			   CRT_HOTPLUG_FORCE_DETECT);
+		spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 		/* wait for FORCE_DETECT to go off */
 		if (wait_for((I915_READ(PORT_HOTPLUG_EN) &
 			      CRT_HOTPLUG_FORCE_DETECT) == 0,
@@ -416,7 +419,11 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector)
 	I915_WRITE(PORT_HOTPLUG_STAT, CRT_HOTPLUG_INT_STATUS);
 
 	/* and put the bits back */
-	I915_WRITE(PORT_HOTPLUG_EN, orig);
+	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+	hotplug_en = I915_READ(PORT_HOTPLUG_EN);
+	hotplug_en &= ~CRT_HOTPLUG_FORCE_DETECT;
+	I915_WRITE(PORT_HOTPLUG_EN, hotplug_en);
+	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 
 	return ret;
 }
-- 
1.8.4.5

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  parent reply	other threads:[~2015-09-01 20:22 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-01 20:21 [PATCH 0/4] Fix numerous issues with HPDstorm handling Egbert Eich
2015-09-01 20:21 ` [PATCH 1/4] drm: Add a non-locking version of drm_kms_helper_poll_enable() Egbert Eich
2015-09-01 21:27   ` Lukas Wunner
2015-09-01 22:10     ` Egbert Eich
2015-09-01 22:31       ` Lukas Wunner
2015-09-02  4:57         ` Egbert Eich
2015-09-01 22:50     ` Egbert Eich
2015-09-02 11:57   ` Daniel Vetter
2015-09-01 20:21 ` [PATCH 2/4] drm/i915: Call " Egbert Eich
2015-09-02 11:58   ` Daniel Vetter
2015-09-23 14:13     ` [PATCH 1/2] drm: Add a non-locking version of drm_kms_helper_poll_enable(), v2 Egbert Eich
2015-09-23 14:13       ` [PATCH 2/2] drm/i915: Call " Egbert Eich
2015-09-23 14:50       ` [PATCH 1/2] drm: Add a " Daniel Vetter
2015-09-24 12:46         ` Jani Nikula
2015-09-25  6:00           ` Egbert Eich
2015-09-25  7:52             ` Jani Nikula
2015-09-29 14:35               ` Jani Nikula
2015-09-30  8:38         ` Jani Nikula
2015-09-01 20:21 ` [PATCH 3/4] drm/i915: Use the correct hpd_status list for non-G4xx/VLV Egbert Eich
2015-09-02 12:00   ` Daniel Vetter
2015-09-02 12:25     ` Imre Deak
2015-09-02 13:42       ` Jani Nikula
2015-09-01 20:21 ` Egbert Eich [this message]
2015-09-02 12:06   ` [PATCH 4/4] drm/i915: Avoid race of intel_crt_detect_hotplug() with HPD interrupt Daniel Vetter
2015-09-02 14:19     ` Egbert Eich
2015-09-02 14:32       ` Jani Nikula
2015-09-02 14:58         ` Egbert Eich
2015-09-02 14:46       ` Daniel Vetter
2015-09-02 15:17         ` Egbert Eich
2015-09-23 14:15         ` [PATCH] drm/i915: Avoid race of intel_crt_detect_hotplug() with HPD interrupt, v2 Egbert Eich
2015-09-23 14:57           ` Daniel Vetter
2015-09-23 15:43             ` Egbert Eich
2015-09-25  6:09               ` [PATCH] drm/i915: On reset/suspend disable hpd pins & cancel pending delayed work Egbert Eich
2015-09-25 12:29                 ` Ville Syrjälä
2015-09-28  7:36                   ` Daniel Vetter

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