linux-kernel - [PATCH v8 1/4] drm/panthor: Rework panthor_irq::suspended into panthor

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Message-Id: <20260112-panthor-tracepoints-v8-1-63efcb421d22@collabora.com>
Date: Mon, 12 Jan 2026 15:37:49 +0100
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: Boris Brezillon <boris.brezillon@...labora.com>, 
 Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Chia-I Wu <olvaffe@...il.com>, Karunika Choo <karunika.choo@....com>
Cc: kernel@...labora.com, linux-kernel@...r.kernel.org, 
 dri-devel@...ts.freedesktop.org, 
 Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: [PATCH v8 1/4] drm/panthor: Rework panthor_irq::suspended into
 panthor_irq::state

To deal with the threaded interrupt handler and a suspend action
overlapping, the boolean panthor_irq::suspended is not sufficient.

Rework it into taking several different values depending on the current
state, and check it and set it within the IRQ helper functions.

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
---
 drivers/gpu/drm/panthor/panthor_device.h | 40 +++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
index f35e52b9546a..424f6cd1a814 100644
--- a/drivers/gpu/drm/panthor/panthor_device.h
+++ b/drivers/gpu/drm/panthor/panthor_device.h
@@ -61,6 +61,17 @@ enum panthor_device_pm_state {
 	PANTHOR_DEVICE_PM_STATE_SUSPENDING,
 };
 
+enum panthor_irq_state {
+	/** @PANTHOR_IRQ_STATE_ACTIVE: IRQ is active and ready to process events. */
+	PANTHOR_IRQ_STATE_ACTIVE = 0,
+	/** @PANTHOR_IRQ_STATE_PROCESSING: IRQ is currently processing events. */
+	PANTHOR_IRQ_STATE_PROCESSING,
+	/** @PANTHOR_IRQ_STATE_SUSPENDED: IRQ is suspended. */
+	PANTHOR_IRQ_STATE_SUSPENDED,
+	/** @PANTHOR_IRQ_STATE_SUSPENDING: IRQ is being suspended. */
+	PANTHOR_IRQ_STATE_SUSPENDING,
+};
+
 /**
  * struct panthor_irq - IRQ data
  *
@@ -76,8 +87,8 @@ struct panthor_irq {
 	/** @mask: Current mask being applied to xxx_INT_MASK. */
 	u32 mask;
 
-	/** @suspended: Set to true when the IRQ is suspended. */
-	atomic_t suspended;
+	/** @state: one of &enum panthor_irq_state reflecting the current state. */
+	atomic_t state;
 };
 
 /**
@@ -409,8 +420,10 @@ static irqreturn_t panthor_ ## __name ## _irq_raw_handler(int irq, void *data)
 {												\
 	struct panthor_irq *pirq = data;							\
 	struct panthor_device *ptdev = pirq->ptdev;						\
+	enum panthor_irq_state state;								\
 												\
-	if (atomic_read(&pirq->suspended))							\
+	state = atomic_read(&pirq->state);							\
+	if (state == PANTHOR_IRQ_STATE_SUSPENDED || state == PANTHOR_IRQ_STATE_SUSPENDING)	\
 		return IRQ_NONE;								\
 	if (!gpu_read(ptdev, __reg_prefix ## _INT_STAT))					\
 		return IRQ_NONE;								\
@@ -423,8 +436,11 @@ static irqreturn_t panthor_ ## __name ## _irq_threaded_handler(int irq, void *da
 {												\
 	struct panthor_irq *pirq = data;							\
 	struct panthor_device *ptdev = pirq->ptdev;						\
+	enum panthor_irq_state state;								\
 	irqreturn_t ret = IRQ_NONE;								\
 												\
+	atomic_cmpxchg(&pirq->state, PANTHOR_IRQ_STATE_ACTIVE, PANTHOR_IRQ_STATE_PROCESSING);	\
+												\
 	while (true) {										\
 		u32 status = gpu_read(ptdev, __reg_prefix ## _INT_RAWSTAT) & pirq->mask;	\
 												\
@@ -435,8 +451,13 @@ static irqreturn_t panthor_ ## __name ## _irq_threaded_handler(int irq, void *da
 		ret = IRQ_HANDLED;								\
 	}											\
 												\
-	if (!atomic_read(&pirq->suspended))							\
-		gpu_write(ptdev, __reg_prefix ## _INT_MASK, pirq->mask);			\
+	state = atomic_read(&pirq->state);							\
+	if (state != PANTHOR_IRQ_STATE_SUSPENDED && state != PANTHOR_IRQ_STATE_SUSPENDING) {	\
+		/* Only restore the bits that were used and are still enabled */		\
+		gpu_write(ptdev, __reg_prefix ## _INT_MASK,					\
+			  gpu_read(ptdev, __reg_prefix ## _INT_MASK) | (mask & pirq->mask));	\
+		atomic_set(&pirq->state, PANTHOR_IRQ_STATE_ACTIVE);				\
+	}											\
 												\
 	return ret;										\
 }												\
@@ -445,16 +466,17 @@ static inline void panthor_ ## __name ## _irq_suspend(struct panthor_irq *pirq)
 {												\
 	pirq->mask = 0;										\
 	gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, 0);					\
+	atomic_set(&pirq->state, PANTHOR_IRQ_STATE_SUSPENDING);					\
 	synchronize_irq(pirq->irq);								\
-	atomic_set(&pirq->suspended, true);							\
+	atomic_set(&pirq->state, PANTHOR_IRQ_STATE_SUSPENDED);					\
 }												\
 												\
 static inline void panthor_ ## __name ## _irq_resume(struct panthor_irq *pirq, u32 mask)	\
 {												\
-	atomic_set(&pirq->suspended, false);							\
 	pirq->mask = mask;									\
-	gpu_write(pirq->ptdev, __reg_prefix ## _INT_CLEAR, mask);				\
-	gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, mask);				\
+	atomic_set(&pirq->state, PANTHOR_IRQ_STATE_ACTIVE);					\
+	gpu_write(pirq->ptdev, __reg_prefix ## _INT_CLEAR, pirq->mask);				\
+	gpu_write(pirq->ptdev, __reg_prefix ## _INT_MASK, pirq->mask);				\
 }												\
 												\
 static int panthor_request_ ## __name ## _irq(struct panthor_device *ptdev,			\

-- 
2.52.0