drm/vmwgfx: Move irq bottom half processing to threads

This gets rid of the irq bottom half tasklets and instead performs the
work needed in process context. We also convert irq-disabling spinlocks to
ordinary spinlocks.

This should decrease system latency for other system components, like
sound for example but has the potential to increase latency for processes
that wait on the GPU.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

1 files changed, 19 insertions, 39 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c
index 86178796de6c..2e5718509c23 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf.c
@@ -85,7 +85,6 @@ struct vmw_cmdbuf_context {
  * Internal protection.
  * @dheaders: Pool of DMA memory for device command buffer headers with trailing
  * space for inline data. Internal protection.
- * @tasklet: Tasklet struct for irq processing. Immutable.
  * @alloc_queue: Wait queue for processes waiting to allocate command buffer
  * space.
  * @idle_queue: Wait queue for processes waiting for command buffer idle.
@@ -117,7 +116,6 @@ struct vmw_cmdbuf_man {
 	spinlock_t lock;
 	struct dma_pool *headers;
 	struct dma_pool *dheaders;
-	struct tasklet_struct tasklet;
 	wait_queue_head_t alloc_queue;
 	wait_queue_head_t idle_queue;
 	bool irq_on;
@@ -278,9 +276,9 @@ void vmw_cmdbuf_header_free(struct vmw_cmdbuf_header *header)
 		vmw_cmdbuf_header_inline_free(header);
 		return;
 	}
-	spin_lock_bh(&man->lock);
+	spin_lock(&man->lock);
 	__vmw_cmdbuf_header_free(header);
-	spin_unlock_bh(&man->lock);
+	spin_unlock(&man->lock);
 }
 
 
@@ -468,20 +466,17 @@ static void vmw_cmdbuf_ctx_add(struct vmw_cmdbuf_man *man,
 }
 
 /**
- * vmw_cmdbuf_man_tasklet - The main part of the command buffer interrupt
- * handler implemented as a tasklet.
+ * vmw_cmdbuf_irqthread - The main part of the command buffer interrupt
+ * handler implemented as a threaded irq task.
  *
- * @data: Tasklet closure. A pointer to the command buffer manager cast to
- * an unsigned long.
+ * @man: Pointer to the command buffer manager.
  *
- * The bottom half (tasklet) of the interrupt handler simply calls into the
+ * The bottom half of the interrupt handler simply calls into the
  * command buffer processor to free finished buffers and submit any
  * queued buffers to hardware.
  */
-static void vmw_cmdbuf_man_tasklet(unsigned long data)
+void vmw_cmdbuf_irqthread(struct vmw_cmdbuf_man *man)
 {
-	struct vmw_cmdbuf_man *man = (struct vmw_cmdbuf_man *) data;
-
 	spin_lock(&man->lock);
 	vmw_cmdbuf_man_process(man);
 	spin_unlock(&man->lock);
@@ -504,7 +499,7 @@ static void vmw_cmdbuf_work_func(struct work_struct *work)
 	uint32_t dummy;
 	bool restart = false;
 
-	spin_lock_bh(&man->lock);
+	spin_lock(&man->lock);
 	list_for_each_entry_safe(entry, next, &man->error, list) {
 		restart = true;
 		DRM_ERROR("Command buffer error.\n");
@@ -513,7 +508,7 @@ static void vmw_cmdbuf_work_func(struct work_struct *work)
 		__vmw_cmdbuf_header_free(entry);
 		wake_up_all(&man->idle_queue);
 	}
-	spin_unlock_bh(&man->lock);
+	spin_unlock(&man->lock);
 
 	if (restart && vmw_cmdbuf_startstop(man, true))
 		DRM_ERROR("Failed restarting command buffer context 0.\n");
@@ -536,7 +531,7 @@ static bool vmw_cmdbuf_man_idle(struct vmw_cmdbuf_man *man,
 	bool idle = false;
 	int i;
 
-	spin_lock_bh(&man->lock);
+	spin_lock(&man->lock);
 	vmw_cmdbuf_man_process(man);
 	for_each_cmdbuf_ctx(man, i, ctx) {
 		if (!list_empty(&ctx->submitted) ||
@@ -548,7 +543,7 @@ static bool vmw_cmdbuf_man_idle(struct vmw_cmdbuf_man *man,
 	idle = list_empty(&man->error);
 
 out_unlock:
-	spin_unlock_bh(&man->lock);
+	spin_unlock(&man->lock);
 
 	return idle;
 }
@@ -571,7 +566,7 @@ static void __vmw_cmdbuf_cur_flush(struct vmw_cmdbuf_man *man)
 	if (!cur)
 		return;
 
-	spin_lock_bh(&man->lock);
+	spin_lock(&man->lock);
 	if (man->cur_pos == 0) {
 		__vmw_cmdbuf_header_free(cur);
 		goto out_unlock;
@@ -580,7 +575,7 @@ static void __vmw_cmdbuf_cur_flush(struct vmw_cmdbuf_man *man)
 	man->cur->cb_header->length = man->cur_pos;
 	vmw_cmdbuf_ctx_add(man, man->cur, SVGA_CB_CONTEXT_0);
 out_unlock:
-	spin_unlock_bh(&man->lock);
+	spin_unlock(&man->lock);
 	man->cur = NULL;
 	man->cur_pos = 0;
 }
@@ -673,14 +668,14 @@ static bool vmw_cmdbuf_try_alloc(struct vmw_cmdbuf_man *man,
 		return true;
  
 	memset(info->node, 0, sizeof(*info->node));
-	spin_lock_bh(&man->lock);
+	spin_lock(&man->lock);
 	ret = drm_mm_insert_node(&man->mm, info->node, info->page_size);
 	if (ret) {
 		vmw_cmdbuf_man_process(man);
 		ret = drm_mm_insert_node(&man->mm, info->node, info->page_size);
 	}
 
-	spin_unlock_bh(&man->lock);
+	spin_unlock(&man->lock);
 	info->done = !ret;
 
 	return info->done;
@@ -801,9 +796,9 @@ static int vmw_cmdbuf_space_pool(struct vmw_cmdbuf_man *man,
 	return 0;
 
 out_no_cb_header:
-	spin_lock_bh(&man->lock);
+	spin_lock(&man->lock);
 	drm_mm_remove_node(&header->node);
-	spin_unlock_bh(&man->lock);
+	spin_unlock(&man->lock);
 
 	return ret;
 }
@@ -1023,18 +1018,6 @@ void vmw_cmdbuf_commit(struct vmw_cmdbuf_man *man, size_t size,
 	vmw_cmdbuf_cur_unlock(man);
 }
 
-/**
- * vmw_cmdbuf_tasklet_schedule - Schedule the interrupt handler bottom half.
- *
- * @man: The command buffer manager.
- */
-void vmw_cmdbuf_tasklet_schedule(struct vmw_cmdbuf_man *man)
-{
-	if (!man)
-		return;
-
-	tasklet_schedule(&man->tasklet);
-}
 
 /**
  * vmw_cmdbuf_send_device_command - Send a command through the device context.
@@ -1059,9 +1042,9 @@ static int vmw_cmdbuf_send_device_command(struct vmw_cmdbuf_man *man,
 	memcpy(cmd, command, size);
 	header->cb_header->length = size;
 	header->cb_context = SVGA_CB_CONTEXT_DEVICE;
-	spin_lock_bh(&man->lock);
+	spin_lock(&man->lock);
 	status = vmw_cmdbuf_header_submit(header);
-	spin_unlock_bh(&man->lock);
+	spin_unlock(&man->lock);
 	vmw_cmdbuf_header_free(header);
 
 	if (status != SVGA_CB_STATUS_COMPLETED) {
@@ -1226,8 +1209,6 @@ struct vmw_cmdbuf_man *vmw_cmdbuf_man_create(struct vmw_private *dev_priv)
 	spin_lock_init(&man->lock);
 	mutex_init(&man->cur_mutex);
 	mutex_init(&man->space_mutex);
-	tasklet_init(&man->tasklet, vmw_cmdbuf_man_tasklet,
-		     (unsigned long) man);
 	man->default_size = VMW_CMDBUF_INLINE_SIZE;
 	init_waitqueue_head(&man->alloc_queue);
 	init_waitqueue_head(&man->idle_queue);
@@ -1297,7 +1278,6 @@ void vmw_cmdbuf_man_destroy(struct vmw_cmdbuf_man *man)
 
 	vmw_generic_waiter_remove(man->dev_priv, SVGA_IRQFLAG_ERROR,
 				  &man->dev_priv->error_waiters);
-	tasklet_kill(&man->tasklet);
 	(void) cancel_work_sync(&man->work);
 	dma_pool_destroy(man->dheaders);
 	dma_pool_destroy(man->headers);