Re: [PATCH 2/2] dmaengine: cppi41: Add basic PM runtime support

[Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>]

* Vinod Koul <vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> [160830 21:45]:
> On Fri, Aug 19, 2016 at 03:59:40PM -0700, Tony Lindgren wrote:
> > Let's keep the device enabled between cppi41_dma_issue_pending()
> > and dmaengine_desc_get_callback_invoke() and rely on the PM runtime
> > autoidle timeout elsewhere.
> > 
> > As the PM runtime is for whole device, not for each channel,
> > we need to queue pending transfers if the device is PM runtime
> > suspended. Then we start the pending transfers in PM runtime
> > resume.
> 
> This fails to apply for me :(
> 
> Can you please rebase and resend this one.

OK sorry about that, that was against Linux next. The conflict
is with c->txd.callback and dmaengine_desc_get_callback_invoke.

Below is a version against your cppi branch.

Regards,

Tony

8< ---------------------
From: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
Date: Wed, 31 Aug 2016 07:19:59 -0700
Subject: [PATCHv2] dmaengine: cppi41: Add basic PM runtime support

Let's keep the device enabled between cppi41_dma_issue_pending()
and dmaengine_desc_get_callback_invoke() and rely on the PM runtime
autoidle timeout elsewhere.

As the PM runtime is for whole device, not for each channel,
we need to queue pending transfers if the device is PM runtime
suspended. Then we start the pending transfers in PM runtime
resume.

Signed-off-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
---
 drivers/dma/cppi41.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 99 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
--- a/drivers/dma/cppi41.c
+++ b/drivers/dma/cppi41.c
@@ -108,6 +108,8 @@ struct cppi41_channel {
 	unsigned td_queued:1;
 	unsigned td_seen:1;
 	unsigned td_desc_seen:1;
+
+	struct list_head node;		/* Node for pending list */
 };
 
 struct cppi41_desc {
@@ -146,6 +148,9 @@ struct cppi41_dd {
 	const struct chan_queues *queues_tx;
 	struct chan_queues td_queue;
 
+	struct list_head pending;	/* Pending queued transfers */
+	spinlock_t lock;		/* Lock for pending list */
+
 	/* context for suspend/resume */
 	unsigned int dma_tdfdq;
 };
@@ -332,6 +337,10 @@ static irqreturn_t cppi41_irq(int irq, void *data)
 			c->residue = pd_trans_len(c->desc->pd6) - len;
 			dma_cookie_complete(&c->txd);
 			c->txd.callback(c->txd.callback_param);
+
+			/* Paired with cppi41_dma_issue_pending */
+			pm_runtime_mark_last_busy(cdd->ddev.dev);
+			pm_runtime_put_autosuspend(cdd->ddev.dev);
 		}
 	}
 	return IRQ_HANDLED;
@@ -349,6 +358,12 @@ static dma_cookie_t cppi41_tx_submit(struct dma_async_tx_descriptor *tx)
 static int cppi41_dma_alloc_chan_resources(struct dma_chan *chan)
 {
 	struct cppi41_channel *c = to_cpp41_chan(chan);
+	struct cppi41_dd *cdd = c->cdd;
+	int error;
+
+	error = pm_runtime_get_sync(cdd->ddev.dev);
+	if (error < 0)
+		return error;
 
 	dma_cookie_init(chan);
 	dma_async_tx_descriptor_init(&c->txd, chan);
@@ -357,11 +372,26 @@ static int cppi41_dma_alloc_chan_resources(struct dma_chan *chan)
 	if (!c->is_tx)
 		cppi_writel(c->q_num, c->gcr_reg + RXHPCRA0);
 
+	pm_runtime_mark_last_busy(cdd->ddev.dev);
+	pm_runtime_put_autosuspend(cdd->ddev.dev);
+
 	return 0;
 }
 
 static void cppi41_dma_free_chan_resources(struct dma_chan *chan)
 {
+	struct cppi41_channel *c = to_cpp41_chan(chan);
+	struct cppi41_dd *cdd = c->cdd;
+	int error;
+
+	error = pm_runtime_get_sync(cdd->ddev.dev);
+	if (error < 0)
+		return;
+
+	WARN_ON(!list_empty(&cdd->pending));
+
+	pm_runtime_mark_last_busy(cdd->ddev.dev);
+	pm_runtime_put_autosuspend(cdd->ddev.dev);
 }
 
 static enum dma_status cppi41_dma_tx_status(struct dma_chan *chan,
@@ -414,11 +444,35 @@ static void push_desc_queue(struct cppi41_channel *c)
 	cppi_writel(reg, cdd->qmgr_mem + QMGR_QUEUE_D(c->q_num));
 }
 
+static void pending_desc(struct cppi41_channel *c)
+{
+	struct cppi41_dd *cdd = c->cdd;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cdd->lock, flags);
+	list_add_tail(&c->node, &cdd->pending);
+	spin_unlock_irqrestore(&cdd->lock, flags);
+}
+
 static void cppi41_dma_issue_pending(struct dma_chan *chan)
 {
 	struct cppi41_channel *c = to_cpp41_chan(chan);
+	struct cppi41_dd *cdd = c->cdd;
+	int error;
+
+	/* PM runtime paired with dmaengine_desc_get_callback_invoke */
+	error = pm_runtime_get(cdd->ddev.dev);
+	if (error < 0) {
+		dev_err(cdd->ddev.dev, "Failed to pm_runtime_get: %i\n",
+			error);
 
-	push_desc_queue(c);
+		return;
+	}
+
+	if (likely(pm_runtime_active(cdd->ddev.dev)))
+		push_desc_queue(c);
+	else
+		pending_desc(c);
 }
 
 static u32 get_host_pd0(u32 length)
@@ -940,12 +994,18 @@ static int cppi41_dma_probe(struct platform_device *pdev)
 	cdd->ctrl_mem = of_iomap(dev->of_node, 1);
 	cdd->sched_mem = of_iomap(dev->of_node, 2);
 	cdd->qmgr_mem = of_iomap(dev->of_node, 3);
+	spin_lock_init(&cdd->lock);
+	INIT_LIST_HEAD(&cdd->pending);
+
+	platform_set_drvdata(pdev, cdd);
 
 	if (!cdd->usbss_mem || !cdd->ctrl_mem || !cdd->sched_mem ||
 			!cdd->qmgr_mem)
 		return -ENXIO;
 
 	pm_runtime_enable(dev);
+	pm_runtime_set_autosuspend_delay(dev, 100);
+	pm_runtime_use_autosuspend(dev);
 	ret = pm_runtime_get_sync(dev);
 	if (ret < 0)
 		goto err_get_sync;
@@ -985,7 +1045,9 @@ static int cppi41_dma_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_of;
 
-	platform_set_drvdata(pdev, cdd);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
 	return 0;
 err_of:
 	dma_async_device_unregister(&cdd->ddev);
@@ -996,7 +1058,8 @@ err_irq:
 err_chans:
 	deinit_cppi41(dev, cdd);
 err_init_cppi:
-	pm_runtime_put(dev);
+	pm_runtime_dont_use_autosuspend(dev);
+	pm_runtime_put_sync(dev);
 err_get_sync:
 	pm_runtime_disable(dev);
 	iounmap(cdd->usbss_mem);
@@ -1021,7 +1084,8 @@ static int cppi41_dma_remove(struct platform_device *pdev)
 	iounmap(cdd->ctrl_mem);
 	iounmap(cdd->sched_mem);
 	iounmap(cdd->qmgr_mem);
-	pm_runtime_put(&pdev->dev);
+	pm_runtime_dont_use_autosuspend(&pdev->dev);
+	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 	return 0;
 }
@@ -1062,9 +1126,39 @@ static int cppi41_resume(struct device *dev)
 
 	return 0;
 }
+
+static int cppi41_runtime_suspend(struct device *dev)
+{
+	struct cppi41_dd *cdd = dev_get_drvdata(dev);
+
+	WARN_ON(!list_empty(&cdd->pending));
+
+	return 0;
+}
+
+static int cppi41_runtime_resume(struct device *dev)
+{
+	struct cppi41_dd *cdd = dev_get_drvdata(dev);
+	struct cppi41_channel *c, *_c;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cdd->lock, flags);
+	list_for_each_entry_safe(c, _c, &cdd->pending, node) {
+		push_desc_queue(c);
+		list_del(&c->node);
+	}
+	spin_unlock_irqrestore(&cdd->lock, flags);
+
+	return 0;
+}
 #endif
 
-static SIMPLE_DEV_PM_OPS(cppi41_pm_ops, cppi41_suspend, cppi41_resume);
+static const struct dev_pm_ops cppi41_pm_ops = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(cppi41_suspend, cppi41_resume)
+	SET_RUNTIME_PM_OPS(cppi41_runtime_suspend,
+			   cppi41_runtime_resume,
+			   NULL)
+};
 
 static struct platform_driver cpp41_dma_driver = {
 	.probe  = cppi41_dma_probe,
-- 
2.9.3

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