accel/ivpu: Use workqueue for IRQ handling

Convert IRQ bottom half from the thread handler into workqueue.
This increases a stability in rare scenarios where driver on
debugging/hardening kernels processes IRQ too slow and misses
some interrupts due to it.
Workqueue handler also gives a very minor performance increase.

Signed-off-by: Maciej Falkowski <maciej.falkowski@linux.intel.com>
Reviewed-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250107173238.381120-6-maciej.falkowski@linux.intel.com

Author: m-falkowski

drivers/accel/ivpu/ivpu_drv.c

@@ -7,6 +7,7 @@
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/pm_runtime.h>
+#include <linux/workqueue.h>
 #include <generated/utsrelease.h>
 
 #include <drm/drm_accel.h>
@@ -421,6 +422,9 @@ void ivpu_prepare_for_reset(struct ivpu_device *vdev)
 {
 	ivpu_hw_irq_disable(vdev);
 	disable_irq(vdev->irq);
+	cancel_work_sync(&vdev->irq_ipc_work);
+	cancel_work_sync(&vdev->irq_dct_work);
+	cancel_work_sync(&vdev->context_abort_work);
 	ivpu_ipc_disable(vdev);
 	ivpu_mmu_disable(vdev);
 }
@@ -465,31 +469,6 @@ static const struct drm_driver driver = {
 	.major = 1,
 };
 
-static irqreturn_t ivpu_irq_thread_handler(int irq, void *arg)
-{
-	struct ivpu_device *vdev = arg;
-	u8 irq_src;
-
-	if (kfifo_is_empty(&vdev->hw->irq.fifo))
-		return IRQ_NONE;
-
-	while (kfifo_get(&vdev->hw->irq.fifo, &irq_src)) {
-		switch (irq_src) {
-		case IVPU_HW_IRQ_SRC_IPC:
-			ivpu_ipc_irq_thread_handler(vdev);
-			break;
-		case IVPU_HW_IRQ_SRC_DCT:
-			ivpu_pm_dct_irq_thread_handler(vdev);
-			break;
-		default:
-			ivpu_err_ratelimited(vdev, "Unknown IRQ source: %u\n", irq_src);
-			break;
-		}
-	}
-
-	return IRQ_HANDLED;
-}
-
 static int ivpu_irq_init(struct ivpu_device *vdev)
 {
 	struct pci_dev *pdev = to_pci_dev(vdev->drm.dev);
@@ -501,12 +480,16 @@ static int ivpu_irq_init(struct ivpu_device *vdev)
 		return ret;
 	}
 
+	INIT_WORK(&vdev->irq_ipc_work, ivpu_ipc_irq_work_fn);
+	INIT_WORK(&vdev->irq_dct_work, ivpu_pm_irq_dct_work_fn);
+	INIT_WORK(&vdev->context_abort_work, ivpu_context_abort_work_fn);
+
 	ivpu_irq_handlers_init(vdev);
 
 	vdev->irq = pci_irq_vector(pdev, 0);
 
-	ret = devm_request_threaded_irq(vdev->drm.dev, vdev->irq, ivpu_hw_irq_handler,
-					ivpu_irq_thread_handler, IRQF_NO_AUTOEN, DRIVER_NAME, vdev);
+	ret = devm_request_irq(vdev->drm.dev, vdev->irq, ivpu_hw_irq_handler,
+			       IRQF_NO_AUTOEN, DRIVER_NAME, vdev);
 	if (ret)
 		ivpu_err(vdev, "Failed to request an IRQ %d\n", ret);
 
@@ -599,8 +582,6 @@ static int ivpu_dev_init(struct ivpu_device *vdev)
 	vdev->db_limit.min = IVPU_MIN_DB;
 	vdev->db_limit.max = IVPU_MAX_DB;
 
-	INIT_WORK(&vdev->context_abort_work, ivpu_context_abort_thread_handler);
-
 	ret = drmm_mutex_init(&vdev->drm, &vdev->context_list_lock);
 	if (ret)
 		goto err_xa_destroy;

drivers/accel/ivpu/ivpu_drv.h

@@ -137,12 +137,15 @@ struct ivpu_device {
 	struct mutex context_list_lock; /* Protects user context addition/removal */
 	struct xarray context_xa;
 	struct xa_limit context_xa_limit;
-	struct work_struct context_abort_work;
 
 	struct xarray db_xa;
 	struct xa_limit db_limit;
 	u32 db_next;
 
+	struct work_struct irq_ipc_work;
+	struct work_struct irq_dct_work;
+	struct work_struct context_abort_work;
+
 	struct mutex bo_list_lock; /* Protects bo_list */
 	struct list_head bo_list;
 

drivers/accel/ivpu/ivpu_hw.c

@@ -285,8 +285,6 @@ void ivpu_hw_profiling_freq_drive(struct ivpu_device *vdev, bool enable)
 
 void ivpu_irq_handlers_init(struct ivpu_device *vdev)
 {
-	INIT_KFIFO(vdev->hw->irq.fifo);
-
 	if (ivpu_hw_ip_gen(vdev) == IVPU_HW_IP_37XX)
 		vdev->hw->irq.ip_irq_handler = ivpu_hw_ip_irq_handler_37xx;
 	else
@@ -300,7 +298,6 @@ void ivpu_irq_handlers_init(struct ivpu_device *vdev)
 
 void ivpu_hw_irq_enable(struct ivpu_device *vdev)
 {
-	kfifo_reset(&vdev->hw->irq.fifo);
 	ivpu_hw_ip_irq_enable(vdev);
 	ivpu_hw_btrs_irq_enable(vdev);
 }
@@ -327,8 +324,6 @@ irqreturn_t ivpu_hw_irq_handler(int irq, void *ptr)
 	/* Re-enable global interrupts to re-trigger MSI for pending interrupts */
 	ivpu_hw_btrs_global_int_enable(vdev);
 
-	if (!kfifo_is_empty(&vdev->hw->irq.fifo))
-		return IRQ_WAKE_THREAD;
 	if (ip_handled || btrs_handled)
 		return IRQ_HANDLED;
 	return IRQ_NONE;

drivers/accel/ivpu/ivpu_hw.h

@@ -6,18 +6,10 @@
 #ifndef __IVPU_HW_H__
 #define __IVPU_HW_H__
 
-#include <linux/kfifo.h>
-
 #include "ivpu_drv.h"
 #include "ivpu_hw_btrs.h"
 #include "ivpu_hw_ip.h"
 
-#define IVPU_HW_IRQ_FIFO_LENGTH 1024
-
-#define IVPU_HW_IRQ_SRC_IPC 1
-#define IVPU_HW_IRQ_SRC_MMU_EVTQ 2
-#define IVPU_HW_IRQ_SRC_DCT 3
-
 struct ivpu_addr_range {
 	resource_size_t start;
 	resource_size_t end;
@@ -27,7 +19,6 @@ struct ivpu_hw_info {
 	struct {
 		bool (*btrs_irq_handler)(struct ivpu_device *vdev, int irq);
 		bool (*ip_irq_handler)(struct ivpu_device *vdev, int irq);
-		DECLARE_KFIFO(fifo, u8, IVPU_HW_IRQ_FIFO_LENGTH);
 	} irq;
 	struct {
 		struct ivpu_addr_range global;

drivers/accel/ivpu/ivpu_hw_btrs.c

@@ -630,8 +630,7 @@ bool ivpu_hw_btrs_irq_handler_lnl(struct ivpu_device *vdev, int irq)
 
 	if (REG_TEST_FLD(VPU_HW_BTRS_LNL_INTERRUPT_STAT, SURV_ERR, status)) {
 		ivpu_dbg(vdev, IRQ, "Survivability IRQ\n");
-		if (!kfifo_put(&vdev->hw->irq.fifo, IVPU_HW_IRQ_SRC_DCT))
-			ivpu_err_ratelimited(vdev, "IRQ FIFO full\n");
+		queue_work(system_wq, &vdev->irq_dct_work);
 	}
 
 	if (REG_TEST_FLD(VPU_HW_BTRS_LNL_INTERRUPT_STAT, FREQ_CHANGE, status))

drivers/accel/ivpu/ivpu_ipc.c

@@ -459,13 +459,12 @@ void ivpu_ipc_irq_handler(struct ivpu_device *vdev)
 		}
 	}
 
-	if (!list_empty(&ipc->cb_msg_list))
-		if (!kfifo_put(&vdev->hw->irq.fifo, IVPU_HW_IRQ_SRC_IPC))
-			ivpu_err_ratelimited(vdev, "IRQ FIFO full\n");
+	queue_work(system_wq, &vdev->irq_ipc_work);
 }
 
-void ivpu_ipc_irq_thread_handler(struct ivpu_device *vdev)
+void ivpu_ipc_irq_work_fn(struct work_struct *work)
 {
+	struct ivpu_device *vdev = container_of(work, struct ivpu_device, irq_ipc_work);
 	struct ivpu_ipc_info *ipc = vdev->ipc;
 	struct ivpu_ipc_rx_msg *rx_msg, *r;
 	struct list_head cb_msg_list;

drivers/accel/ivpu/ivpu_ipc.h

@@ -90,7 +90,7 @@ void ivpu_ipc_disable(struct ivpu_device *vdev);
 void ivpu_ipc_reset(struct ivpu_device *vdev);
 
 void ivpu_ipc_irq_handler(struct ivpu_device *vdev);
-void ivpu_ipc_irq_thread_handler(struct ivpu_device *vdev);
+void ivpu_ipc_irq_work_fn(struct work_struct *work);
 
 void ivpu_ipc_consumer_add(struct ivpu_device *vdev, struct ivpu_ipc_consumer *cons,
 			   u32 channel, ivpu_ipc_rx_callback_t callback);

drivers/accel/ivpu/ivpu_job.c

@@ -935,7 +935,7 @@ void ivpu_job_done_consumer_fini(struct ivpu_device *vdev)
 	ivpu_ipc_consumer_del(vdev, &vdev->job_done_consumer);
 }
 
-void ivpu_context_abort_thread_handler(struct work_struct *work)
+void ivpu_context_abort_work_fn(struct work_struct *work)
 {
 	struct ivpu_device *vdev = container_of(work, struct ivpu_device, context_abort_work);
 	struct ivpu_file_priv *file_priv;

drivers/accel/ivpu/ivpu_job.h

@@ -72,7 +72,7 @@ void ivpu_cmdq_abort_all_jobs(struct ivpu_device *vdev, u32 ctx_id, u32 cmdq_id)
 
 void ivpu_job_done_consumer_init(struct ivpu_device *vdev);
 void ivpu_job_done_consumer_fini(struct ivpu_device *vdev);
-void ivpu_context_abort_thread_handler(struct work_struct *work);
+void ivpu_context_abort_work_fn(struct work_struct *work);
 
 void ivpu_jobs_abort_all(struct ivpu_device *vdev);
 

drivers/accel/ivpu/ivpu_pm.c

@@ -452,8 +452,9 @@ int ivpu_pm_dct_disable(struct ivpu_device *vdev)
 	return 0;
 }
 
-void ivpu_pm_dct_irq_thread_handler(struct ivpu_device *vdev)
+void ivpu_pm_irq_dct_work_fn(struct work_struct *work)
 {
+	struct ivpu_device *vdev = container_of(work, struct ivpu_device, irq_dct_work);
 	bool enable;
 	int ret;