linux-kernel - Re: [PATCH 2/4] spi: mt7621: Use the devm_clk_get_enabled() helper to simplify error handling

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Message-ID: <ae3523f9-6420-9413-30cf-ab6a081c8500@gmail.com>
Date:   Mon, 29 Aug 2022 13:14:52 +0200
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        broonie@...nel.org, gregkh@...uxfoundation.org, neil@...wn.name,
        blogic@...nwrt.org
Cc:     linux-spi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 2/4] spi: mt7621: Use the devm_clk_get_enabled() helper to
 simplify error handling



On 27/08/2022 13:42, Christophe JAILLET wrote:
> The devm_clk_get_enabled() helper:
>     - calls devm_clk_get()
>     - calls clk_prepare_enable() and registers what is needed in order to
>       call clk_disable_unprepare() when needed, as a managed resource.
> 
> This helper is well suited for cases where the clock would be kept
> prepared or enabled for the whole lifetime of the driver.
> 
> This simplifies the error handling a lot.
> 
> The order between spi_unregister_controller() (in the remove function) and
> the clk_disable_unprepare() (now handle by a  managed resource) is kept
> the same.
> (see commit 46b5c4fb87ce ("spi: mt7621: Don't leak SPI master in probe
> error path") to see why it matters)
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>

Reviewed-by: Matthias Brugger <matthias.bgg@...il.com>

> ---
> The order with  devm_spi_release_controller() (which undoes
> devm_spi_alloc_master()) is reversed, but I don't think it is an issue.
> ---
>   drivers/spi/spi-mt7621.c | 14 +-------------
>   1 file changed, 1 insertion(+), 13 deletions(-)
> 
> diff --git a/drivers/spi/spi-mt7621.c b/drivers/spi/spi-mt7621.c
> index 351b0ef52bbc..2580b28042be 100644
> --- a/drivers/spi/spi-mt7621.c
> +++ b/drivers/spi/spi-mt7621.c
> @@ -327,7 +327,6 @@ static int mt7621_spi_probe(struct platform_device *pdev)
>   	struct spi_controller *master;
>   	struct mt7621_spi *rs;
>   	void __iomem *base;
> -	int status = 0;
>   	struct clk *clk;
>   	int ret;
>   
> @@ -339,19 +338,14 @@ static int mt7621_spi_probe(struct platform_device *pdev)
>   	if (IS_ERR(base))
>   		return PTR_ERR(base);
>   
> -	clk = devm_clk_get(&pdev->dev, NULL);
> +	clk = devm_clk_get_enabled(&pdev->dev, NULL);
>   	if (IS_ERR(clk))
>   		return dev_err_probe(&pdev->dev, PTR_ERR(clk),
>   				     "unable to get SYS clock\n");
>   
> -	status = clk_prepare_enable(clk);
> -	if (status)
> -		return status;
> -
>   	master = devm_spi_alloc_master(&pdev->dev, sizeof(*rs));
>   	if (!master) {
>   		dev_info(&pdev->dev, "master allocation failed\n");
> -		clk_disable_unprepare(clk);
>   		return -ENOMEM;
>   	}
>   
> @@ -376,13 +370,10 @@ static int mt7621_spi_probe(struct platform_device *pdev)
>   	ret = device_reset(&pdev->dev);
>   	if (ret) {
>   		dev_err(&pdev->dev, "SPI reset failed!\n");
> -		clk_disable_unprepare(clk);
>   		return ret;
>   	}
>   
>   	ret = spi_register_controller(master);
> -	if (ret)
> -		clk_disable_unprepare(clk);
>   
>   	return ret;
>   }
> @@ -390,13 +381,10 @@ static int mt7621_spi_probe(struct platform_device *pdev)
>   static int mt7621_spi_remove(struct platform_device *pdev)
>   {
>   	struct spi_controller *master;
> -	struct mt7621_spi *rs;
>   
>   	master = dev_get_drvdata(&pdev->dev);
> -	rs = spi_controller_get_devdata(master);
>   
>   	spi_unregister_controller(master);
> -	clk_disable_unprepare(rs->clk);
>   
>   	return 0;
>   }