linux-kernel - [PATCH 2/2] nouveau: Acknowledge HPD irq in handler, not bottom half

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Date:	Wed, 10 Nov 2010 16:32:05 -0500
From:	Andy Lutomirski <luto@....EDU>
To:	Ben Skeggs <bskeggs@...hat.com>, dri-devel@...ts.freedesktop.org
Cc:	linux-kernel@...r.kernel.org, Andy Lutomirski <luto@....edu>
Subject: [PATCH 2/2] nouveau: Acknowledge HPD irq in handler, not bottom half

The old code generated an interrupt storm bad enough to completely
take down my system.

This only fixes the bits that are defined nouveau_regs.h.  Newer hardware
uses another register that isn't described, and I don't have that hardware
to test.

Signed-off-by: Andy Lutomirski <luto@....edu>
Cc: <stable@...nel.org>
---
 drivers/gpu/drm/nouveau/nouveau_drv.h  |    5 +++++
 drivers/gpu/drm/nouveau/nouveau_irq.c  |    1 +
 drivers/gpu/drm/nouveau/nv50_display.c |   17 +++++++++++++----
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
index b1be617..b6c62cc 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -531,6 +531,11 @@ struct drm_nouveau_private {
 	struct work_struct irq_work;
 	struct work_struct hpd_work;
 
+	struct {
+		spinlock_t lock;
+		uint32_t hpd0_bits;
+	} hpd_state;
+
 	struct list_head vbl_waiting;
 
 	struct {
diff --git a/drivers/gpu/drm/nouveau/nouveau_irq.c b/drivers/gpu/drm/nouveau/nouveau_irq.c
index 794b0ee..b62a601 100644
--- a/drivers/gpu/drm/nouveau/nouveau_irq.c
+++ b/drivers/gpu/drm/nouveau/nouveau_irq.c
@@ -52,6 +52,7 @@ nouveau_irq_preinstall(struct drm_device *dev)
 	if (dev_priv->card_type >= NV_50) {
 		INIT_WORK(&dev_priv->irq_work, nv50_display_irq_handler_bh);
 		INIT_WORK(&dev_priv->hpd_work, nv50_display_irq_hotplug_bh);
+		spin_lock_init(&dev_priv->hpd_state.lock);
 		INIT_LIST_HEAD(&dev_priv->vbl_waiting);
 	}
 }
diff --git a/drivers/gpu/drm/nouveau/nv50_display.c b/drivers/gpu/drm/nouveau/nv50_display.c
index 83a7d27..0df08e3 100644
--- a/drivers/gpu/drm/nouveau/nv50_display.c
+++ b/drivers/gpu/drm/nouveau/nv50_display.c
@@ -1014,7 +1014,12 @@ nv50_display_irq_hotplug_bh(struct work_struct *work)
 	uint32_t unplug_mask, plug_mask, change_mask;
 	uint32_t hpd0, hpd1 = 0;
 
-	hpd0 = nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL) & nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_INTR);
+	spin_lock_irq(&dev_priv->hpd_state.lock);
+	hpd0 = dev_priv->hpd_state.hpd0_bits;
+	dev_priv->hpd_state.hpd0_bits = 0;
+	spin_unlock_irq(&dev_priv->hpd_state.lock);
+
+	hpd0 &= nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_INTR);
 	if (dev_priv->chipset >= 0x90)
 		hpd1 = nv_rd32(dev, 0xe074) & nv_rd32(dev, 0xe070);
 
@@ -1058,7 +1063,6 @@ nv50_display_irq_hotplug_bh(struct work_struct *work)
 			helper->dpms(connector->encoder, DRM_MODE_DPMS_OFF);
 	}
 
-	nv_wr32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL, nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL));
 	if (dev_priv->chipset >= 0x90)
 		nv_wr32(dev, 0xe074, nv_rd32(dev, 0xe074));
 
@@ -1072,8 +1076,13 @@ nv50_display_irq_handler(struct drm_device *dev)
 	uint32_t delayed = 0;
 
 	if (nv_rd32(dev, NV50_PMC_INTR_0) & NV50_PMC_INTR_0_HOTPLUG) {
-		if (!work_pending(&dev_priv->hpd_work))
-			queue_work(dev_priv->wq, &dev_priv->hpd_work);
+		uint32_t hpd0_bits = nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL);
+		nv_wr32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL, hpd0_bits);
+		spin_lock(&dev_priv->hpd_state.lock);
+		dev_priv->hpd_state.hpd0_bits |= hpd0_bits;
+		spin_unlock(&dev_priv->hpd_state.lock);
+
+		queue_work(dev_priv->wq, &dev_priv->hpd_work);
 	}
 
 	while (nv_rd32(dev, NV50_PMC_INTR_0) & NV50_PMC_INTR_0_DISPLAY) {
-- 
1.7.3.2

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