linux-kernel - [PATCH 2/2] dmaengine: dw-axi-dmac: add reset control support

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Message-ID: <20251012100002.2959213-3-a.shimko.dev@gmail.com>
Date: Sun, 12 Oct 2025 13:00:00 +0300
From: Artem Shimko <a.shimko.dev@...il.com>
To: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
	Vinod Koul <vkoul@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>
Cc: a.shimko.dev@...il.com,
	dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] dmaengine: dw-axi-dmac: add reset control support

Add proper reset control handling to the AXI DMA driver to ensure
reliable initialization and power management. The driver now manages
resets during probe, remove, and system suspend/resume operations.

The implementation stores reset control in the chip structure and adds
reset assert/deassert calls at the appropriate points: resets are
deasserted during probe after clock acquisition, asserted during remove
and error cleanup, and properly managed during suspend/resume cycles.
Additionally, proper error handling is implemented for reset control
operations to ensure robust behavior.

This ensures the controller is properly reset during power transitions
and prevents potential issues with incomplete initialization.

Signed-off-by: Artem Shimko <a.shimko.dev@...il.com>
---
 .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    | 41 ++++++++++++-------
 drivers/dma/dw-axi-dmac/dw-axi-dmac.h         |  2 +
 2 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
index 8b7cf3baf5d3..3f4dd2178498 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -1321,6 +1321,9 @@ static int axi_dma_suspend(struct device *dev)
 	axi_dma_irq_disable(chip);
 	axi_dma_disable(chip);
 
+	if (chip->has_resets)
+		reset_control_assert(chip->resets);
+
 	clk_disable_unprepare(chip->core_clk);
 	clk_disable_unprepare(chip->cfgr_clk);
 
@@ -1340,6 +1343,9 @@ static int axi_dma_resume(struct device *dev)
 	if (ret < 0)
 		return ret;
 
+	if (chip->has_resets)
+		reset_control_deassert(chip->resets);
+
 	axi_dma_enable(chip);
 	axi_dma_irq_enable(chip);
 
@@ -1455,7 +1461,6 @@ static int dw_probe(struct platform_device *pdev)
 	struct axi_dma_chip *chip;
 	struct dw_axi_dma *dw;
 	struct dw_axi_dma_hcfg *hdata;
-	struct reset_control *resets;
 	unsigned int flags;
 	u32 i;
 	int ret;
@@ -1487,16 +1492,6 @@ static int dw_probe(struct platform_device *pdev)
 			return PTR_ERR(chip->apb_regs);
 	}
 
-	if (flags & AXI_DMA_FLAG_HAS_RESETS) {
-		resets = devm_reset_control_array_get_exclusive(&pdev->dev);
-		if (IS_ERR(resets))
-			return PTR_ERR(resets);
-
-		ret = reset_control_deassert(resets);
-		if (ret)
-			return ret;
-	}
-
 	chip->dw->hdata->use_cfg2 = !!(flags & AXI_DMA_FLAG_USE_CFG2);
 
 	chip->core_clk = devm_clk_get(chip->dev, "core-clk");
@@ -1507,18 +1502,31 @@ static int dw_probe(struct platform_device *pdev)
 	if (IS_ERR(chip->cfgr_clk))
 		return PTR_ERR(chip->cfgr_clk);
 
+	chip->has_resets = !!(flags & AXI_DMA_FLAG_HAS_RESETS);
+	if (chip->has_resets) {
+		chip->resets = devm_reset_control_array_get_exclusive(&pdev->dev);
+		if (IS_ERR(chip->resets))
+			return PTR_ERR(chip->resets);
+
+		ret = reset_control_deassert(chip->resets);
+		if (ret)
+			return dev_err_probe(&pdev->dev, ret, "Failed to deassert resets\n");
+	}
+
 	ret = parse_device_properties(chip);
 	if (ret)
-		return ret;
+		goto err_exit;
 
 	dw->chan = devm_kcalloc(chip->dev, hdata->nr_channels,
 				sizeof(*dw->chan), GFP_KERNEL);
-	if (!dw->chan)
-		return -ENOMEM;
+	if (!dw->chan) {
+		ret = -ENOMEM;
+		goto err_exit;
+	}
 
 	ret = axi_req_irqs(pdev, chip);
 	if (ret)
-		return ret;
+		goto err_exit;
 
 	INIT_LIST_HEAD(&dw->dma.channels);
 	for (i = 0; i < hdata->nr_channels; i++) {
@@ -1605,6 +1613,9 @@ static int dw_probe(struct platform_device *pdev)
 
 err_pm_disable:
 	pm_runtime_disable(chip->dev);
+err_exit:
+	if (chip->has_resets)
+		reset_control_assert(chip->resets);
 
 	return ret;
 }
diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
index b842e6a8d90d..56dc3d75fe92 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
@@ -71,6 +71,8 @@ struct axi_dma_chip {
 	struct clk		*core_clk;
 	struct clk		*cfgr_clk;
 	struct dw_axi_dma	*dw;
+	struct reset_control	*resets;
+	bool			has_resets;
 };
 
 /* LLI == Linked List Item */
-- 
2.43.0