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Message-ID: <66a2c261.43970.187b7da0d97.Coremail.m202171703@hust.edu.cn>
Date: Tue, 25 Apr 2023 17:58:53 +0800 (GMT+08:00)
From: 张网 <m202171703@...t.edu.cn>
To: "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
Subject: Re: [PATCH v3] i2c: ocores: use devm_ managed clks
ping?
"Wang Zhang" <silver_code@...t.edu.cn>写道：
> If any wrong occurs in ocores_i2c_of_probe, the i2c->clk needs to be
> released. But the function returns directly in line 701 without freeing
> the clock. Even though we can fix it by freeing the clock manually if
> platform_get_irq_optional fails, it may not be following the best practice.
> The original code for this driver contains if (IS_ERR()) checks
> throughout, explicitly allowing the driver to continue loading even if
> devm_clk_get() fails.
>
> 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>
> ---
> 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 | 56 +++++++++++++--------------------
> 1 file changed, 22 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
> index 2e575856c5cd..0b225177fdd1 100644
> --- a/drivers/i2c/busses/i2c-ocores.c
> +++ b/drivers/i2c/busses/i2c-ocores.c
> @@ -552,16 +552,15 @@ 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 (IS_ERR(i2c->clk)) {
> + dev_err(&pdev->dev,
> + "devm_clk_get_optional_enabled failed\n");
> + return PTR_ERR(i2c->clk);
> + }
>
> - if (ret) {
> - dev_err(&pdev->dev,
> - "clk_prepare_enable failed: %d\n", ret);
> - return ret;
> - }
> + 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 +572,6 @@ 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 +676,7 @@ 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 +707,13 @@ 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 +725,7 @@ 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 +734,6 @@ 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 +748,6 @@ 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 +761,7 @@ 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 +769,18 @@ 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;
> + if (rate)
> + i2c->ip_clock_khz = rate;
> +
> return ocores_init(dev, i2c);
> }
>
> --
> 2.34.1
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