Message-Id: <20250912-b4-edma-runtime-v3-1-be22f7161745@nxp.com>
Date: Fri, 12 Sep 2025 18:55:42 +0800
From: Joy Zou <joy.zou@....com>
To: Frank Li <Frank.Li@....com>, Vinod Koul <vkoul@...nel.org>
Cc: imx@...ts.linux.dev, dmaengine@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Joy Zou <joy.zou@....com>
Subject: [PATCH v3] dmaegnine: fsl-edma: add runtime suspend/resume support

Introduce runtime suspend and resume support for FSL eDMA. Enable
per-channel power domain management to facilitate runtime suspend and
resume operations.

Implement runtime suspend and resume functions for the eDMA engine and
individual channels.

Link per-channel power domain device to eDMA per-channel device instead of
eDMA engine device. So Power Manage framework manage power state of linked
domain device when per-channel device request runtime resume/suspend.

Trigger the eDMA engine's runtime suspend when all channels are suspended,
disabling all common clocks through the runtime PM framework.

Signed-off-by: Joy Zou <joy.zou@....com>
Signed-off-by: Frank Li <Frank.Li@....com>
Reviewed-by: Frank Li <Frank.Li@....com>
---
Changes for V3:
- rebased onto commit 8f21d9da4670 ("Add linux-next specific files for 20250911")
  to align with latest changes.
- Remove pm_runtime_dont_use_autosuspend() from fsl_edma3_detach_pd().
  because the autosuspend is not used.
- Move some edma channel registers initialization after the chan_dev
  pm_runtime_enable().
- Add clk_prepare_enable() return check in fsl_edma_runtime_resume.
- Add flag FSL_EDMA_DRV_HAS_DMACLK check in fsl_edma_runtime_resume/suspend().
- Link to v2: https://lore.kernel.org/imx/20241226052643.1951886-1-joy.zou@nxp.com/

Changes for V2:
- drop ret from fsl_edma_chan_runtime_suspend().
- drop ret from fsl_edma_chan_runtime_resume() and return clk_prepare_enable().
- add review tag
- Link to v1: https://lore.kernel.org/imx/20241220021109.2102294-1-joy.zou@nxp.com/
---
Changes in v4:
- EDITME: describe what is new in this series revision.
- EDITME: use bulletpoints and terse descriptions.
- Link to v3: https://lore.kernel.org/r/20250912-b4-edma-runtime-v3-1-2d4a4f83603f@nxp.com
---
 drivers/dma/fsl-edma-common.c |  15 ++---
 drivers/dma/fsl-edma-main.c   | 129 +++++++++++++++++++++++++++++++++++-------
 2 files changed, 116 insertions(+), 28 deletions(-)

diff --git a/drivers/dma/fsl-edma-common.c b/drivers/dma/fsl-edma-common.c
index 4976d7dde08090d16277af4b9f784b9745485320..55cb094088d569b87cde78a36734a1fc7e251b73 100644
--- a/drivers/dma/fsl-edma-common.c
+++ b/drivers/dma/fsl-edma-common.c
@@ -243,9 +243,6 @@ int fsl_edma_terminate_all(struct dma_chan *chan)
 	spin_unlock_irqrestore(&fsl_chan->vchan.lock, flags);
 	vchan_dma_desc_free_list(&fsl_chan->vchan, &head);
 
-	if (fsl_edma_drvflags(fsl_chan) & FSL_EDMA_DRV_HAS_PD)
-		pm_runtime_allow(fsl_chan->pd_dev);
-
 	return 0;
 }
 
@@ -823,8 +820,12 @@ int fsl_edma_alloc_chan_resources(struct dma_chan *chan)
 	struct fsl_edma_chan *fsl_chan = to_fsl_edma_chan(chan);
 	int ret = 0;
 
-	if (fsl_edma_drvflags(fsl_chan) & FSL_EDMA_DRV_HAS_CHCLK)
-		clk_prepare_enable(fsl_chan->clk);
+	ret = pm_runtime_get_sync(&fsl_chan->vchan.chan.dev->device);
+	if (ret < 0) {
+		dev_err(&fsl_chan->vchan.chan.dev->device, "pm_runtime_get_sync() failed\n");
+		pm_runtime_disable(&fsl_chan->vchan.chan.dev->device);
+		return ret;
+	}
 
 	fsl_chan->tcd_pool = dma_pool_create("tcd_pool", chan->device->dev,
 				fsl_edma_drvflags(fsl_chan) & FSL_EDMA_DRV_TCD64 ?
@@ -852,6 +853,7 @@ int fsl_edma_alloc_chan_resources(struct dma_chan *chan)
 		free_irq(fsl_chan->txirq, fsl_chan);
 err_txirq:
 	dma_pool_destroy(fsl_chan->tcd_pool);
+	pm_runtime_put_sync_suspend(&fsl_chan->vchan.chan.dev->device);
 
 	return ret;
 }
@@ -883,8 +885,7 @@ void fsl_edma_free_chan_resources(struct dma_chan *chan)
 	fsl_chan->is_sw = false;
 	fsl_chan->srcid = 0;
 	fsl_chan->is_remote = false;
-	if (fsl_edma_drvflags(fsl_chan) & FSL_EDMA_DRV_HAS_CHCLK)
-		clk_disable_unprepare(fsl_chan->clk);
+	pm_runtime_put_sync_suspend(&fsl_chan->vchan.chan.dev->device);
 }
 
 void fsl_edma_cleanup_vchan(struct dma_device *dmadev)
diff --git a/drivers/dma/fsl-edma-main.c b/drivers/dma/fsl-edma-main.c
index 97583c7d51a2e8e7a50c7eb4f5ff0582ac95798d..e06f4240fdeb8839493f00c63b640eb3aa795b91 100644
--- a/drivers/dma/fsl-edma-main.c
+++ b/drivers/dma/fsl-edma-main.c
@@ -642,7 +642,6 @@ static void fsl_edma3_detach_pd(struct fsl_edma_engine *fsl_edma)
 			device_link_del(fsl_chan->pd_dev_link);
 		if (fsl_chan->pd_dev) {
 			dev_pm_domain_detach(fsl_chan->pd_dev, false);
-			pm_runtime_dont_use_autosuspend(fsl_chan->pd_dev);
 			pm_runtime_set_suspended(fsl_chan->pd_dev);
 		}
 	}
@@ -673,23 +672,8 @@ static int fsl_edma3_attach_pd(struct platform_device *pdev, struct fsl_edma_eng
 			dev_err(dev, "Failed attach pd %d\n", i);
 			goto detach;
 		}
-
-		fsl_chan->pd_dev_link = device_link_add(dev, pd_chan, DL_FLAG_STATELESS |
-					     DL_FLAG_PM_RUNTIME |
-					     DL_FLAG_RPM_ACTIVE);
-		if (!fsl_chan->pd_dev_link) {
-			dev_err(dev, "Failed to add device_link to %d\n", i);
-			dev_pm_domain_detach(pd_chan, false);
-			goto detach;
-		}
-
 		fsl_chan->pd_dev = pd_chan;
-
-		pm_runtime_use_autosuspend(fsl_chan->pd_dev);
-		pm_runtime_set_autosuspend_delay(fsl_chan->pd_dev, 200);
-		pm_runtime_set_active(fsl_chan->pd_dev);
 	}
-
 	return 0;
 
 detach:
@@ -697,6 +681,29 @@ static int fsl_edma3_attach_pd(struct platform_device *pdev, struct fsl_edma_eng
 	return -EINVAL;
 }
 
+/* Per channel dma power domain */
+static int fsl_edma_chan_runtime_suspend(struct device *dev)
+{
+	struct fsl_edma_chan *fsl_chan = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(fsl_chan->clk);
+
+	return 0;
+}
+
+static int fsl_edma_chan_runtime_resume(struct device *dev)
+{
+	struct fsl_edma_chan *fsl_chan = dev_get_drvdata(dev);
+
+	return clk_prepare_enable(fsl_chan->clk);
+}
+
+static struct dev_pm_domain fsl_edma_chan_pm_domain = {
+	.ops = {
+	       RUNTIME_PM_OPS(fsl_edma_chan_runtime_suspend, fsl_edma_chan_runtime_resume, NULL)
+	}
+};
+
 static int fsl_edma_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
@@ -826,11 +833,6 @@ static int fsl_edma_probe(struct platform_device *pdev)
 		}
 		fsl_chan->pdev = pdev;
 		vchan_init(&fsl_chan->vchan, &fsl_edma->dma_dev);
-
-		edma_write_tcdreg(fsl_chan, cpu_to_le32(0), csr);
-		fsl_edma_chan_mux(fsl_chan, 0, false);
-		if (fsl_chan->edma->drvdata->flags & FSL_EDMA_DRV_HAS_CHCLK)
-			clk_disable_unprepare(fsl_chan->clk);
 	}
 
 	ret = fsl_edma->drvdata->setup_irq(pdev, fsl_edma);
@@ -889,6 +891,45 @@ static int fsl_edma_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	pm_runtime_enable(&pdev->dev);
+
+	for (i = 0; i < fsl_edma->n_chans; i++) {
+		struct fsl_edma_chan *fsl_chan = &fsl_edma->chans[i];
+		struct device *chan_dev;
+
+		if (fsl_edma->chan_masked & BIT(i))
+			continue;
+
+		chan_dev = &fsl_chan->vchan.chan.dev->device;
+		dev_set_drvdata(chan_dev, fsl_chan);
+		dev_pm_domain_set(chan_dev, &fsl_edma_chan_pm_domain);
+
+		if (fsl_chan->pd_dev) {
+			fsl_chan->pd_dev_link = device_link_add(chan_dev, fsl_chan->pd_dev,
+								DL_FLAG_STATELESS |
+								DL_FLAG_PM_RUNTIME |
+								DL_FLAG_RPM_ACTIVE);
+			if (!fsl_chan->pd_dev_link) {
+				dev_pm_domain_detach(fsl_chan->pd_dev, false);
+				fsl_edma3_detach_pd(fsl_edma);
+				return dev_err_probe(&pdev->dev, -EINVAL,
+						     "Failed to add device_link to %d\n", i);
+			}
+			pm_runtime_put_sync_suspend(fsl_chan->pd_dev);
+		}
+		pm_runtime_enable(chan_dev);
+
+		if (fsl_chan->pd_dev)
+			pm_runtime_get_sync(fsl_chan->pd_dev);
+
+		edma_write_tcdreg(fsl_chan, cpu_to_le32(0), csr);
+		fsl_edma_chan_mux(fsl_chan, 0, false);
+		if (fsl_chan->edma->drvdata->flags & FSL_EDMA_DRV_HAS_CHCLK)
+			clk_disable_unprepare(fsl_chan->clk);
+		if (fsl_chan->pd_dev)
+			pm_runtime_put_sync_suspend(fsl_chan->pd_dev);
+	}
+
 	ret = of_dma_controller_register(np,
 			drvdata->dmamuxs ? fsl_edma_xlate : fsl_edma3_xlate,
 			fsl_edma);
@@ -929,6 +970,13 @@ static int fsl_edma_suspend_late(struct device *dev)
 		fsl_chan = &fsl_edma->chans[i];
 		if (fsl_edma->chan_masked & BIT(i))
 			continue;
+
+		if (pm_runtime_status_suspended(&fsl_chan->vchan.chan.dev->device) ||
+		    (!(fsl_edma->drvdata->flags & FSL_EDMA_DRV_HAS_PD) &&
+		     (fsl_edma->drvdata->flags & FSL_EDMA_DRV_SPLIT_REG) &&
+		     !fsl_chan->srcid))
+			continue;
+
 		spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
 		/* Make sure chan is idle or will force disable. */
 		if (unlikely(fsl_chan->status == DMA_IN_PROGRESS)) {
@@ -955,6 +1003,13 @@ static int fsl_edma_resume_early(struct device *dev)
 		fsl_chan = &fsl_edma->chans[i];
 		if (fsl_edma->chan_masked & BIT(i))
 			continue;
+
+		if (pm_runtime_status_suspended(&fsl_chan->vchan.chan.dev->device) ||
+		    (!(fsl_edma->drvdata->flags & FSL_EDMA_DRV_HAS_PD) &&
+		     (fsl_edma->drvdata->flags & FSL_EDMA_DRV_SPLIT_REG) &&
+		     !fsl_chan->srcid))
+			continue;
+
 		fsl_chan->pm_state = RUNNING;
 		edma_write_tcdreg(fsl_chan, 0, csr);
 		if (fsl_chan->srcid != 0)
@@ -967,6 +1022,37 @@ static int fsl_edma_resume_early(struct device *dev)
 	return 0;
 }
 
+/* edma engine runtime system/resume */
+static int fsl_edma_runtime_suspend(struct device *dev)
+{
+	struct fsl_edma_engine *fsl_edma = dev_get_drvdata(dev);
+	int i;
+
+	for (i = 0; i < fsl_edma->drvdata->dmamuxs; i++)
+		clk_disable_unprepare(fsl_edma->muxclk[i]);
+
+	if (fsl_edma->drvdata->flags & FSL_EDMA_DRV_HAS_DMACLK)
+		clk_disable_unprepare(fsl_edma->dmaclk);
+
+	return 0;
+}
+
+static int fsl_edma_runtime_resume(struct device *dev)
+{
+	struct fsl_edma_engine *fsl_edma = dev_get_drvdata(dev);
+	int i, ret;
+
+	for (i = 0; i < fsl_edma->drvdata->dmamuxs; i++) {
+		ret = clk_prepare_enable(fsl_edma->muxclk[i]);
+		if (ret)
+			return ret;
+	}
+
+	if (fsl_edma->drvdata->flags & FSL_EDMA_DRV_HAS_DMACLK)
+		return clk_prepare_enable(fsl_edma->dmaclk);
+	return 0;
+}
+
 /*
  * eDMA provides the service to others, so it should be suspend late
  * and resume early. When eDMA suspend, all of the clients should stop
@@ -975,6 +1061,7 @@ static int fsl_edma_resume_early(struct device *dev)
 static const struct dev_pm_ops fsl_edma_pm_ops = {
 	.suspend_late   = fsl_edma_suspend_late,
 	.resume_early   = fsl_edma_resume_early,
+	 RUNTIME_PM_OPS(fsl_edma_runtime_suspend, fsl_edma_runtime_resume, NULL)
 };
 
 static struct platform_driver fsl_edma_driver = {

---
base-commit: 8f21d9da46702c4d6951ba60ca8a05f42870fe8f
change-id: 20250912-b4-edma-runtime-23f744a0527b

Best regards,
-- 
Joy Zou <joy.zou@....com>

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