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Message-ID: <68c4b991-6af9-36e8-354c-7c3b232ba4c2@wanadoo.fr>
Date: Wed, 24 May 2023 21:21:56 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Wang Zhang <silver_code@...t.edu.cn>,
Peter Korsgaard <peter@...sgaard.com>,
Andrew Lunn <andrew@...n.ch>
Cc: hust-os-kernel-patches@...glegroups.com, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org,
Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [PATCH v3] i2c: ocores: use devm_ managed clks
Le 24/05/2023 à 17:43, Wang Zhang a écrit :
> While it is not entirely clear why the original author implemented this
> behavior, there may have been certain circumstances or issues that were not
> apparent to us. It's possible that they were trying to work around a bug by
> employing an unconventional solution.Using `devm_clk_get_enabled()` rather
> than devm_clk_get() can automatically track the usage of clocks and free
> them when they are no longer needed or an error occurs.
>
> fixing it by changing `ocores_i2c_of_probe` to use
> `devm_clk_get_optional_enabled()` rather than `devm_clk_get()`, changing
> `goto err_clk' to direct return and removing `err_clk`.
>
> Signed-off-by: Wang Zhang <silver_code@...t.edu.cn>
> Reviewed-by: Andrew Lunn <andrew@...n.ch>
> ---
> v2->v3: use `devm_clk_get_optional_enabled()` to manage clks
> v1->v2: change `ocores_i2c_of_probe` to use `devm_clk_get_enabled()`
> ---
> drivers/i2c/busses/i2c-ocores.c | 57 +++++++++++++--------------------
> 1 file changed, 22 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
> index 2e575856c5cd..316d72cde3b9 100644
> --- a/drivers/i2c/busses/i2c-ocores.c
> +++ b/drivers/i2c/busses/i2c-ocores.c
> @@ -552,16 +552,14 @@ static int ocores_i2c_of_probe(struct platform_device *pdev,
> &clock_frequency);
> i2c->bus_clock_khz = 100;
>
> - i2c->clk = devm_clk_get(&pdev->dev, NULL);
> + i2c->clk = devm_clk_get_optional_enabled(&pdev->dev, NULL);
>
> - if (!IS_ERR(i2c->clk)) {
> - int ret = clk_prepare_enable(i2c->clk);
> -
> - if (ret) {
> - dev_err(&pdev->dev,
> - "clk_prepare_enable failed: %d\n", ret);
> - return ret;
> - }
> + if (IS_ERR(i2c->clk)) {
> + dev_err(&pdev->dev,
> + "devm_clk_get_optional_enabled failed\n");
Maybe dev_err_probe() would be nice here. This would log the error code,
and filter -EPROBE_DEFER, should it happen.
> + return PTR_ERR(i2c->clk);
> + }
> + if (i2c->clk) {
> i2c->ip_clock_khz = clk_get_rate(i2c->clk) / 1000;
> if (clock_frequency_present)
> i2c->bus_clock_khz = clock_frequency / 1000;
> @@ -573,7 +571,6 @@ static int ocores_i2c_of_probe(struct platform_device *pdev,
> if (!clock_frequency_present) {
> dev_err(&pdev->dev,
> "Missing required parameter 'opencores,ip-clock-frequency'\n");
> - clk_disable_unprepare(i2c->clk);
> return -ENODEV;
> }
> i2c->ip_clock_khz = clock_frequency / 1000;
> @@ -678,8 +675,7 @@ static int ocores_i2c_probe(struct platform_device *pdev)
> default:
> dev_err(&pdev->dev, "Unsupported I/O width (%d)\n",
> i2c->reg_io_width);
> - ret = -EINVAL;
> - goto err_clk;
> + return -EINVAL;
> }
> }
>
> @@ -710,13 +706,13 @@ static int ocores_i2c_probe(struct platform_device *pdev)
> pdev->name, i2c);
> if (ret) {
> dev_err(&pdev->dev, "Cannot claim IRQ\n");
> - goto err_clk;
> + return ret;
> }
> }
>
> ret = ocores_init(&pdev->dev, i2c);
> if (ret)
> - goto err_clk;
> + return ret;
>
> /* hook up driver to tree */
> platform_set_drvdata(pdev, i2c);
> @@ -728,7 +724,7 @@ static int ocores_i2c_probe(struct platform_device *pdev)
> /* add i2c adapter to i2c tree */
> ret = i2c_add_adapter(&i2c->adap);
> if (ret)
> - goto err_clk;
> + return ret;
>
> /* add in known devices to the bus */
> if (pdata) {
> @@ -737,10 +733,6 @@ static int ocores_i2c_probe(struct platform_device *pdev)
> }
>
> return 0;
> -
> -err_clk:
> - clk_disable_unprepare(i2c->clk);
> - return ret;
> }
>
> static int ocores_i2c_remove(struct platform_device *pdev)
> @@ -755,9 +747,6 @@ static int ocores_i2c_remove(struct platform_device *pdev)
> /* remove adapter & data */
> i2c_del_adapter(&i2c->adap);
>
> - if (!IS_ERR(i2c->clk))
> - clk_disable_unprepare(i2c->clk);
> -
> return 0;
> }
>
> @@ -771,8 +760,7 @@ static int ocores_i2c_suspend(struct device *dev)
> ctrl &= ~(OCI2C_CTRL_EN | OCI2C_CTRL_IEN);
> oc_setreg(i2c, OCI2C_CONTROL, ctrl);
>
> - if (!IS_ERR(i2c->clk))
> - clk_disable_unprepare(i2c->clk);
> + clk_disable_unprepare(i2c->clk);
> return 0;
> }
>
> @@ -780,19 +768,18 @@ static int ocores_i2c_resume(struct device *dev)
> {
> struct ocores_i2c *i2c = dev_get_drvdata(dev);
>
> - if (!IS_ERR(i2c->clk)) {
> - unsigned long rate;
> - int ret = clk_prepare_enable(i2c->clk);
> + unsigned long rate;
> + int ret = clk_prepare_enable(i2c->clk);
>
> - if (ret) {
> - dev_err(dev,
> - "clk_prepare_enable failed: %d\n", ret);
> - return ret;
> - }
> - rate = clk_get_rate(i2c->clk) / 1000;
> - if (rate)
> - i2c->ip_clock_khz = rate;
> + if (ret) {
> + dev_err(dev,
> + "clk_prepare_enable failed: %d\n", ret);
> + return ret;
> }
> + rate = clk_get_rate(i2c->clk) / 1000;
Now (because of the devm_clk_get_optional_enabled()), i2c->clk can be
NULL, so this would deference a NULL pointer.
CJ
> + if (rate)
> + i2c->ip_clock_khz = rate;
> +
> return ocores_init(dev, i2c);
> }
>
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