linux-kernel - Re: [PATCH v5] dma-engine: sun4i: Use devm functions in probe()

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Message-ID: <071b4cf6-df18-4232-b2ae-6b8bee48899d@wanadoo.fr>
Date: Sat, 22 Mar 2025 22:37:55 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Bence Csókás <csokas.bence@...lan.hu>,
 dmaengine@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Cc: Markus Elfring <Markus.Elfring@....de>, Chen-Yu Tsai <wens@...nel.org>,
 Jernej Skrabec <jernej.skrabec@...il.com>, Chen-Yu Tsai <wens@...e.org>,
 Vinod Koul <vkoul@...nel.org>, Samuel Holland <samuel@...lland.org>
Subject: Re: [PATCH v5] dma-engine: sun4i: Use devm functions in probe()

Le 22/03/2025 à 20:36, Bence Csókás a écrit :
> Clean up error handling by using devm functions and dev_err_probe(). This
> should make it easier to add new code, as we can eliminate the "goto
> ladder" in probe().
> 
> Suggested-by: Chen-Yu Tsai <wens@...nel.org>
> Reviewed-by: Jernej Skrabec <jernej.skrabec@...il.com>
> Acked-by: Chen-Yu Tsai <wens@...e.org>
> Signed-off-by: Bence Csókás <csokas.bence@...lan.hu>
> ---
> 
> Notes:
>      Changes in v2:
>      * rebase on current next
>      Changes in v3:
>      * rebase on current next
>      * collect Jernej's tag
>      Changes in v4:
>      * rebase on current next
>      * collect Chen-Yu's tag
>      Changes in v5:
>      * reformat msg to 75 cols
>      * keep `\n`s in error messages
> 
>   drivers/dma/sun4i-dma.c | 31 ++++++-------------------------
>   1 file changed, 6 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/dma/sun4i-dma.c b/drivers/dma/sun4i-dma.c
> index 24796aaaddfa..59ecebfc8eed 100644
> --- a/drivers/dma/sun4i-dma.c
> +++ b/drivers/dma/sun4i-dma.c
> @@ -1249,10 +1249,9 @@ static int sun4i_dma_probe(struct platform_device *pdev)
>   	if (priv->irq < 0)
>   		return priv->irq;
>   
> -	priv->clk = devm_clk_get(&pdev->dev, NULL);
> +	priv->clk = devm_clk_get_enabled(&pdev->dev, NULL);
>   	if (IS_ERR(priv->clk)) {
> -		dev_err(&pdev->dev, "No clock specified\n");
> -		return PTR_ERR(priv->clk);
> +		return dev_err_probe(&pdev->dev, PTR_ERR(priv->clk), "Couldn't start the clock\n");

I think that it would be better to keep the message on another line, to 
avoid too long lines.

>   	}

In several places, now {} around a single statement looks unneeded.

CJ

>   
>   	if (priv->cfg->has_reset) {
> @@ -1328,12 +1327,6 @@ static int sun4i_dma_probe(struct platform_device *pdev)
>   		vchan_init(&vchan->vc, &priv->slave);
>   	}
>   
> -	ret = clk_prepare_enable(priv->clk);
> -	if (ret) {
> -		dev_err(&pdev->dev, "Couldn't enable the clock\n");
> -		return ret;
> -	}
> -
>   	/*
>   	 * Make sure the IRQs are all disabled and accounted for. The bootloader
>   	 * likes to leave these dirty
> @@ -1344,32 +1337,23 @@ static int sun4i_dma_probe(struct platform_device *pdev)
>   	ret = devm_request_irq(&pdev->dev, priv->irq, sun4i_dma_interrupt,
>   			       0, dev_name(&pdev->dev), priv);
>   	if (ret) {
> -		dev_err(&pdev->dev, "Cannot request IRQ\n");
> -		goto err_clk_disable;
> +		return dev_err_probe(&pdev->dev, ret, "Cannot request IRQ\n");
>   	}
>   
> -	ret = dma_async_device_register(&priv->slave);
> +	ret = dmaenginem_async_device_register(&priv->slave);
>   	if (ret) {
> -		dev_warn(&pdev->dev, "Failed to register DMA engine device\n");
> -		goto err_clk_disable;
> +		return dev_err_probe(&pdev->dev, ret, "Failed to register DMA engine device\n");
>   	}
>   
>   	ret = of_dma_controller_register(pdev->dev.of_node, sun4i_dma_of_xlate,
>   					 priv);
>   	if (ret) {
> -		dev_err(&pdev->dev, "of_dma_controller_register failed\n");
> -		goto err_dma_unregister;
> +		return dev_err_probe(&pdev->dev, ret, "Failed to register translation function\n");
>   	}
>   
>   	dev_dbg(&pdev->dev, "Successfully probed SUN4I_DMA\n");
>   
>   	return 0;
> -
> -err_dma_unregister:
> -	dma_async_device_unregister(&priv->slave);
> -err_clk_disable:
> -	clk_disable_unprepare(priv->clk);
> -	return ret;
>   }
>   
>   static void sun4i_dma_remove(struct platform_device *pdev)
> @@ -1380,9 +1364,6 @@ static void sun4i_dma_remove(struct platform_device *pdev)
>   	disable_irq(priv->irq);
>   
>   	of_dma_controller_free(pdev->dev.of_node);
> -	dma_async_device_unregister(&priv->slave);
> -
> -	clk_disable_unprepare(priv->clk);
>   }
>   
>   static struct sun4i_dma_config sun4i_a10_dma_cfg = {