dmaengine: dw-axi-dmac: convert clock handling to clk_bulk API

[PATCH v2] dmaengine: dw-axi-dmac: convert clock handling to clk_bulk API

Posted by Chaithanya Lagisetty 1 month, 1 week ago

The driver managed its two mandatory clocks (core-clk and cfgr-clk)
individually. This was error prone: axi_dma_resume() enabled cfgr_clk
and then core_clk, and if enabling core_clk failed it returned the
error without disabling cfgr_clk, leaving the clock refcount
unbalanced.

Convert the driver to the clk_bulk API. The two clocks are always
acquired, enabled and disabled together, so a clk_bulk_data array
expresses this naturally and shrinks the get/enable/disable paths.
clk_bulk_prepare_enable() also unwinds any clock it already enabled
when a later one fails, which fixes the resume imbalance.

Fixes: 1fe20f1b8454 ("dmaengine: Introduce DW AXI DMAC driver")
Signed-off-by: Chaithanya Lagisetty <nagachaithanya9911@gmail.com>
---
Changes since v1:
- Convert the driver to the clk_bulk API instead of manually disabling
  cfgr_clk on the error path, as suggested by Frank Li.
- v1: https://lore.kernel.org/all/20260813105432.2577322-1-nagachaithanya9911@gmail.com/

 .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    | 28 ++++++++-----------
 drivers/dma/dw-axi-dmac/dw-axi-dmac.h         |  3 +-
 2 files changed, 13 insertions(+), 18 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 bcefaff03b5c..254167a558ff 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -1320,8 +1320,7 @@ static int axi_dma_suspend(struct axi_dma_chip *chip)
 	axi_dma_irq_disable(chip);
 	axi_dma_disable(chip);
 
-	clk_disable_unprepare(chip->core_clk);
-	clk_disable_unprepare(chip->cfgr_clk);
+	clk_bulk_disable_unprepare(ARRAY_SIZE(chip->clks), chip->clks);
 
 	return 0;
 }
@@ -1330,11 +1329,7 @@ static int axi_dma_resume(struct axi_dma_chip *chip)
 {
 	int ret;
 
-	ret = clk_prepare_enable(chip->cfgr_clk);
-	if (ret < 0)
-		return ret;
-
-	ret = clk_prepare_enable(chip->core_clk);
+	ret = clk_bulk_prepare_enable(ARRAY_SIZE(chip->clks), chip->clks);
 	if (ret < 0)
 		return ret;
 
@@ -1524,13 +1519,11 @@ static int dw_probe(struct platform_device *pdev)
 
 	chip->dw->hdata->use_cfg2 = !!(flags & AXI_DMA_FLAG_USE_CFG2);
 
-	chip->core_clk = devm_clk_get(chip->dev, "core-clk");
-	if (IS_ERR(chip->core_clk))
-		return PTR_ERR(chip->core_clk);
-
-	chip->cfgr_clk = devm_clk_get(chip->dev, "cfgr-clk");
-	if (IS_ERR(chip->cfgr_clk))
-		return PTR_ERR(chip->cfgr_clk);
+	chip->clks[0].id = "core-clk";
+	chip->clks[1].id = "cfgr-clk";
+	ret = devm_clk_bulk_get(chip->dev, ARRAY_SIZE(chip->clks), chip->clks);
+	if (ret)
+		return dev_err_probe(chip->dev, ret, "failed to get clocks\n");
 
 	ret = parse_device_properties(chip);
 	if (ret)
@@ -1640,10 +1633,13 @@ static void dw_remove(struct platform_device *pdev)
 	struct dw_axi_dma *dw = chip->dw;
 	struct axi_dma_chan *chan, *_chan;
 	u32 i;
+	int ret;
 
 	/* Enable clk before accessing to registers */
-	clk_prepare_enable(chip->cfgr_clk);
-	clk_prepare_enable(chip->core_clk);
+	ret = clk_bulk_prepare_enable(ARRAY_SIZE(chip->clks), chip->clks);
+	if (ret)
+		dev_warn(chip->dev, "failed to enable clocks before remove: %d\n",
+			 ret);
 	axi_dma_irq_disable(chip);
 	for (i = 0; i < dw->hdata->nr_channels; i++) {
 		axi_chan_disable(&chip->dw->chan[i]);
diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
index 67cc199e24d1..039316c42f05 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
@@ -69,8 +69,7 @@ struct axi_dma_chip {
 	int			irq[DMAC_MAX_CHANNELS];
 	void __iomem		*regs;
 	void __iomem		*apb_regs;
-	struct clk		*core_clk;
-	struct clk		*cfgr_clk;
+	struct clk_bulk_data	clks[2];
 	struct dw_axi_dma	*dw;
 };
 
-- 
2.43.0

Re: [PATCH v2] dmaengine: dw-axi-dmac: convert clock handling to clk_bulk API

Posted by Vinod Koul 3 weeks, 4 days ago

On Sun, 16 Aug 2026 05:48:58 +0000, Chaithanya Lagisetty wrote:
> The driver managed its two mandatory clocks (core-clk and cfgr-clk)
> individually. This was error prone: axi_dma_resume() enabled cfgr_clk
> and then core_clk, and if enabling core_clk failed it returned the
> error without disabling cfgr_clk, leaving the clock refcount
> unbalanced.
> 
> Convert the driver to the clk_bulk API. The two clocks are always
> acquired, enabled and disabled together, so a clk_bulk_data array
> expresses this naturally and shrinks the get/enable/disable paths.
> clk_bulk_prepare_enable() also unwinds any clock it already enabled
> when a later one fails, which fixes the resume imbalance.
> 
> [...]

Applied, thanks!

[1/1] dmaengine: dw-axi-dmac: convert clock handling to clk_bulk API
      commit: 110126f425c34a2b189e10e74eec7644e1b47827

Best regards,
-- 
~Vinod

Re: [PATCH v2] dmaengine: dw-axi-dmac: convert clock handling to clk_bulk API

Posted by Frank Li 1 month, 1 week ago

On Sun, Aug 16, 2026 at 05:48:58AM +0000, Chaithanya Lagisetty wrote:
> The driver managed its two mandatory clocks (core-clk and cfgr-clk)
> individually. This was error prone: axi_dma_resume() enabled cfgr_clk
> and then core_clk, and if enabling core_clk failed it returned the
> error without disabling cfgr_clk, leaving the clock refcount
> unbalanced.
>
> Convert the driver to the clk_bulk API. The two clocks are always
> acquired, enabled and disabled together, so a clk_bulk_data array
> expresses this naturally and shrinks the get/enable/disable paths.
> clk_bulk_prepare_enable() also unwinds any clock it already enabled
> when a later one fails, which fixes the resume imbalance.
>
> Fixes: 1fe20f1b8454 ("dmaengine: Introduce DW AXI DMAC driver")
> Signed-off-by: Chaithanya Lagisetty <nagachaithanya9911@gmail.com>
> ---

Again, don't post new patch to old patch's thread.

Reviewed-by: Frank Li <Frank.Li@nxp.com>

> Changes since v1:
> - Convert the driver to the clk_bulk API instead of manually disabling
>   cfgr_clk on the error path, as suggested by Frank Li.
> - v1: https://lore.kernel.org/all/20260813105432.2577322-1-nagachaithanya9911@gmail.com/
>
>  .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    | 28 ++++++++-----------
>  drivers/dma/dw-axi-dmac/dw-axi-dmac.h         |  3 +-
>  2 files changed, 13 insertions(+), 18 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 bcefaff03b5c..254167a558ff 100644
> --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
> @@ -1320,8 +1320,7 @@ static int axi_dma_suspend(struct axi_dma_chip *chip)
>  	axi_dma_irq_disable(chip);
>  	axi_dma_disable(chip);
>
> -	clk_disable_unprepare(chip->core_clk);
> -	clk_disable_unprepare(chip->cfgr_clk);
> +	clk_bulk_disable_unprepare(ARRAY_SIZE(chip->clks), chip->clks);
>
>  	return 0;
>  }
> @@ -1330,11 +1329,7 @@ static int axi_dma_resume(struct axi_dma_chip *chip)
>  {
>  	int ret;
>
> -	ret = clk_prepare_enable(chip->cfgr_clk);
> -	if (ret < 0)
> -		return ret;
> -
> -	ret = clk_prepare_enable(chip->core_clk);
> +	ret = clk_bulk_prepare_enable(ARRAY_SIZE(chip->clks), chip->clks);
>  	if (ret < 0)
>  		return ret;
>
> @@ -1524,13 +1519,11 @@ static int dw_probe(struct platform_device *pdev)
>
>  	chip->dw->hdata->use_cfg2 = !!(flags & AXI_DMA_FLAG_USE_CFG2);
>
> -	chip->core_clk = devm_clk_get(chip->dev, "core-clk");
> -	if (IS_ERR(chip->core_clk))
> -		return PTR_ERR(chip->core_clk);
> -
> -	chip->cfgr_clk = devm_clk_get(chip->dev, "cfgr-clk");
> -	if (IS_ERR(chip->cfgr_clk))
> -		return PTR_ERR(chip->cfgr_clk);
> +	chip->clks[0].id = "core-clk";
> +	chip->clks[1].id = "cfgr-clk";
> +	ret = devm_clk_bulk_get(chip->dev, ARRAY_SIZE(chip->clks), chip->clks);
> +	if (ret)
> +		return dev_err_probe(chip->dev, ret, "failed to get clocks\n");
>
>  	ret = parse_device_properties(chip);
>  	if (ret)
> @@ -1640,10 +1633,13 @@ static void dw_remove(struct platform_device *pdev)
>  	struct dw_axi_dma *dw = chip->dw;
>  	struct axi_dma_chan *chan, *_chan;
>  	u32 i;
> +	int ret;
>
>  	/* Enable clk before accessing to registers */
> -	clk_prepare_enable(chip->cfgr_clk);
> -	clk_prepare_enable(chip->core_clk);
> +	ret = clk_bulk_prepare_enable(ARRAY_SIZE(chip->clks), chip->clks);
> +	if (ret)
> +		dev_warn(chip->dev, "failed to enable clocks before remove: %d\n",
> +			 ret);
>  	axi_dma_irq_disable(chip);
>  	for (i = 0; i < dw->hdata->nr_channels; i++) {
>  		axi_chan_disable(&chip->dw->chan[i]);
> diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> index 67cc199e24d1..039316c42f05 100644
> --- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> +++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
> @@ -69,8 +69,7 @@ struct axi_dma_chip {
>  	int			irq[DMAC_MAX_CHANNELS];
>  	void __iomem		*regs;
>  	void __iomem		*apb_regs;
> -	struct clk		*core_clk;
> -	struct clk		*cfgr_clk;
> +	struct clk_bulk_data	clks[2];
>  	struct dw_axi_dma	*dw;
>  };
>
> --
> 2.43.0
>