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Date:	Fri, 11 Jul 2014 00:50:17 +0300
From:	Oded Gabbay <oded.gabbay@...il.com>
To:	David Airlie <airlied@...ux.ie>,
	Alex Deucher <alexander.deucher@....com>,
	Jerome Glisse <j.glisse@...il.com>
Cc:	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	John Bridgman <John.Bridgman@....com>,
	Andrew Lewycky <Andrew.Lewycky@....com>,
	Joerg Roedel <joro@...tes.org>,
	Oded Gabbay <oded.gabbay@....com>
Subject: [PATCH 17/83] hsa/radeon: Handle deactivation of queues using interrupts

This patch modifies the scheduler code to use interrupts to handle the
deactivation of queues. We prefer to use interrupts because the
deactivation could take a long time since we need to wait for the
wavefront to finish executing before deactivating the queue.

There is an array of waitqueues, each cell is represents queues for a
specific pipe. When a queue should be deactivated, it is inserted to the
wait queue. The event that triggers the waitqueue is a dequeue-complete
interrupt that arrives through the isr function of the scheduler.

Signed-off-by: Oded Gabbay <oded.gabbay@....com>
---
 drivers/gpu/hsa/radeon/cik_regs.h             |  1 +
 drivers/gpu/hsa/radeon/kfd_sched_cik_static.c | 45 +++++++++++++++++++++------
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/hsa/radeon/cik_regs.h b/drivers/gpu/hsa/radeon/cik_regs.h
index ef1d7ab..9c3ce97 100644
--- a/drivers/gpu/hsa/radeon/cik_regs.h
+++ b/drivers/gpu/hsa/radeon/cik_regs.h
@@ -166,6 +166,7 @@
 
 #define CP_HQD_DEQUEUE_REQUEST				0xC974
 #define	DEQUEUE_REQUEST_DRAIN				1
+#define		DEQUEUE_INT					(1U << 8)
 
 #define CP_HQD_SEMA_CMD					0xC97Cu
 #define CP_HQD_MSG_TYPE					0xC980u
diff --git a/drivers/gpu/hsa/radeon/kfd_sched_cik_static.c b/drivers/gpu/hsa/radeon/kfd_sched_cik_static.c
index f86f958..5d42e88 100644
--- a/drivers/gpu/hsa/radeon/kfd_sched_cik_static.c
+++ b/drivers/gpu/hsa/radeon/kfd_sched_cik_static.c
@@ -139,6 +139,13 @@ struct cik_static_private {
 	 /* Queue q on pipe p is at bit QUEUES_PER_PIPE * p + q. */
 	unsigned long free_queues[DIV_ROUND_UP(CIK_MAX_PIPES * CIK_QUEUES_PER_PIPE, BITS_PER_LONG)];
 
+	/*
+	 * Dequeue waits for waves to finish so it could take a long time. We
+	 * defer through an interrupt. dequeue_wait is woken when a dequeue-
+	 * complete interrupt comes for that pipe.
+	 */
+	wait_queue_head_t dequeue_wait[CIK_MAX_PIPES];
+
 	kfd_mem_obj hpd_mem;	/* Single allocation for HPDs for all KFD pipes. */
 	kfd_mem_obj mqd_mem;	/* Single allocation for all MQDs for all KFD
 				 * pipes. This is actually struct cik_mqd_padded. */
@@ -411,6 +418,9 @@ static int cik_static_create(struct kfd_dev *dev, struct kfd_scheduler **schedul
 
 	priv->free_vmid_mask = dev->shared_resources.compute_vmid_bitmap;
 
+	for (i = 0; i < priv->num_pipes; i++)
+		init_waitqueue_head(&priv->dequeue_wait[i]);
+
 	/*
 	 * Allocate memory for the HPDs. This is hardware-owned per-pipe data.
 	 * The driver never accesses this memory after zeroing it. It doesn't even have
@@ -712,15 +722,18 @@ static void activate_queue(struct cik_static_private *priv, struct cik_static_qu
 	unlock_srbm_index(priv);
 }
 
-static void drain_hqd(struct cik_static_private *priv)
+static bool queue_inactive(struct cik_static_private *priv, struct cik_static_queue *queue)
 {
-	WRITE_REG(priv->dev, CP_HQD_DEQUEUE_REQUEST, DEQUEUE_REQUEST_DRAIN);
-}
+	bool inactive;
 
-static void wait_hqd_inactive(struct cik_static_private *priv)
-{
-	while (READ_REG(priv->dev, CP_HQD_ACTIVE) != 0)
-		cpu_relax();
+	lock_srbm_index(priv);
+	queue_select(priv, queue->queue);
+
+	inactive = (READ_REG(priv->dev, CP_HQD_ACTIVE) == 0);
+
+	unlock_srbm_index(priv);
+
+	return inactive;
 }
 
 static void deactivate_queue(struct cik_static_private *priv, struct cik_static_queue *queue)
@@ -728,10 +741,12 @@ static void deactivate_queue(struct cik_static_private *priv, struct cik_static_
 	lock_srbm_index(priv);
 	queue_select(priv, queue->queue);
 
-	drain_hqd(priv);
-	wait_hqd_inactive(priv);
+	WRITE_REG(priv->dev, CP_HQD_DEQUEUE_REQUEST, DEQUEUE_REQUEST_DRAIN | DEQUEUE_INT);
 
 	unlock_srbm_index(priv);
+
+	wait_event(priv->dequeue_wait[queue->queue/CIK_QUEUES_PER_PIPE],
+		   queue_inactive(priv, queue));
 }
 
 #define BIT_MASK_64(high, low) (((1ULL << (high)) - 1) & ~((1ULL << (low)) - 1))
@@ -791,6 +806,14 @@ cik_static_destroy_queue(struct kfd_scheduler *scheduler, struct kfd_scheduler_q
 	release_hqd(priv, hwq->queue);
 }
 
+static void
+dequeue_int_received(struct cik_static_private *priv, uint32_t pipe_id)
+{
+	/* The waiting threads will check CP_HQD_ACTIVE to see whether their
+	 * queue completed. */
+	wake_up_all(&priv->dequeue_wait[pipe_id]);
+}
+
 /* Figure out the KFD compute pipe ID for an interrupt ring entry.
  * Returns true if it's a KFD compute pipe, false otherwise. */
 static bool int_compute_pipe(const struct cik_static_private *priv,
@@ -829,6 +852,10 @@ cik_static_interrupt_isr(struct kfd_scheduler *scheduler, const void *ih_ring_en
 		 ihre->source_id, ihre->data, pipe_id, ihre->vmid, ihre->pasid);
 
 	switch (source_id) {
+	case CIK_INTSRC_DEQUEUE_COMPLETE:
+		dequeue_int_received(priv, pipe_id);
+		return false; /* Already handled. */
+
 	default:
 		return false; /* Not interested. */
 	}
-- 
1.9.1

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