linux-kernel - [PATCH 1/4] irqchip: imgpdc: Avoid unbalanced irq wake disable

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Date:   Mon,  2 Oct 2017 10:55:56 +0100
From:   Ed Blake <ed.blake@...drel.com>
To:     tglx@...utronix.de, jason@...edaemon.net, marc.zyngier@....com
Cc:     linux-kernel@...r.kernel.org, Ed Blake <ed.blake@...drel.com>
Subject: [PATCH 1/4] irqchip: imgpdc: Avoid unbalanced irq wake disable

To avoid 'unbalanced irq wake disable' kernel warnings, only pass on
wake disables to the parent irq controller if the previous wake enable
succeeded.

Some platforms utilise the wake capability of the parent irq
controller, so we must attempt to pass on wake enables to the parent.
But in other platforms the wake capability of the PDC is used, when
the parent isn't required to support wake and we need to avoid
unbalanced wake disables in this case.

Signed-off-by: Ed Blake <ed.blake@...drel.com>
---
 drivers/irqchip/irq-imgpdc.c | 62 ++++++++++++++++++++++++++++++++------------
 1 file changed, 46 insertions(+), 16 deletions(-)

diff --git a/drivers/irqchip/irq-imgpdc.c b/drivers/irqchip/irq-imgpdc.c
index c02d29c..2ac3210 100644
--- a/drivers/irqchip/irq-imgpdc.c
+++ b/drivers/irqchip/irq-imgpdc.c
@@ -63,21 +63,25 @@
 
 /**
  * struct pdc_intc_priv - private pdc interrupt data.
- * @nr_perips:		Number of peripheral interrupt signals.
- * @nr_syswakes:	Number of syswake signals.
- * @perip_irqs:		List of peripheral IRQ numbers handled.
- * @syswake_irq:	Shared PDC syswake IRQ number.
- * @domain:		IRQ domain for PDC peripheral and syswake IRQs.
- * @pdc_base:		Base of PDC registers.
- * @irq_route:		Cached version of PDC_IRQ_ROUTE register.
- * @lock:		Lock to protect the PDC syswake registers and the cached
- *			values of those registers in this struct.
+ * @nr_perips:			Number of peripheral interrupt signals.
+ * @nr_syswakes:		Number of syswake signals.
+ * @perip_irqs:			List of peripheral IRQ numbers handled.
+ * @perip_irq_wake_depths:	List of peripheral IRQs wake depths.
+ * @syswake_irq:		Shared PDC syswake IRQ number.
+ * @syswake_irq_wake_depth:	Shared PDC syswake IRQ wake depth.
+ * @domain:			IRQ domain for PDC peripheral and syswake IRQs.
+ * @pdc_base:			Base of PDC registers.
+ * @irq_route:			Cached version of PDC_IRQ_ROUTE register.
+ * @lock:			Lock to protect the PDC syswake regs and the
+ *				cached values of those regs in this struct.
  */
 struct pdc_intc_priv {
 	unsigned int		nr_perips;
 	unsigned int		nr_syswakes;
 	unsigned int		*perip_irqs;
+	unsigned int		*perip_irq_wake_depths;
 	unsigned int		syswake_irq;
+	unsigned int		syswake_irq_wake_depth;
 	struct irq_domain	*domain;
 	void __iomem		*pdc_base;
 
@@ -199,6 +203,17 @@ static int pdc_irq_set_wake(struct irq_data *data, unsigned int on)
 	irq_hw_number_t hw = data->hwirq;
 	unsigned int mask = (1 << 16) << hw;
 	unsigned int dst_irq;
+	unsigned int *dst_irq_wake_depth;
+	int ret;
+
+	/* control the destination IRQ wakeup too for standby mode */
+	if (hwirq_is_syswake(hw)) {
+		dst_irq = priv->syswake_irq;
+		dst_irq_wake_depth = &priv->syswake_irq_wake_depth;
+	} else {
+		dst_irq = priv->perip_irqs[hw];
+		dst_irq_wake_depth = &priv->perip_irq_wake_depths[hw];
+	}
 
 	raw_spin_lock(&priv->lock);
 	if (on)
@@ -206,14 +221,22 @@ static int pdc_irq_set_wake(struct irq_data *data, unsigned int on)
 	else
 		priv->irq_route &= ~mask;
 	pdc_write(priv, PDC_IRQ_ROUTE, priv->irq_route);
-	raw_spin_unlock(&priv->lock);
 
-	/* control the destination IRQ wakeup too for standby mode */
-	if (hwirq_is_syswake(hw))
-		dst_irq = priv->syswake_irq;
-	else
-		dst_irq = priv->perip_irqs[hw];
-	irq_set_irq_wake(dst_irq, on);
+	/*
+	 * Pass on the set_wake request to the parent interrupt controller.
+	 * The parent isn't required to support wake, but we must balance
+	 * successful irq_set_irq_wake calls.
+	 */
+	if (on || *dst_irq_wake_depth) {
+		ret = irq_set_irq_wake(dst_irq, on);
+		if (!ret) {
+			if (on)
+				(*dst_irq_wake_depth)++;
+			else
+				(*dst_irq_wake_depth)--;
+		}
+	}
+	raw_spin_unlock(&priv->lock);
 
 	return 0;
 }
@@ -359,6 +382,13 @@ static int pdc_intc_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "cannot allocate perip IRQ list\n");
 		return -ENOMEM;
 	}
+	priv->perip_irq_wake_depths = devm_kzalloc(&pdev->dev,
+						   4 * priv->nr_perips,
+						   GFP_KERNEL);
+	if (!priv->perip_irq_wake_depths) {
+		dev_err(&pdev->dev, "cannot allocate perip IRQ wake depth list\n");
+		return -ENOMEM;
+	}
 	for (i = 0; i < priv->nr_perips; ++i) {
 		irq = platform_get_irq(pdev, 1 + i);
 		if (irq < 0) {
-- 
1.9.1