Re: [PATCH v5 1/2] i2c: imx-lpi2c: properly unwind resources on probe failure

[Frank Li]

On Tue, Jun 30, 2026 at 06:52:22PM +0800, carlos.song@xxxxxxxxxxx wrote:
> From: Carlos Song <carlos.song@xxxxxxx>
>
> When probe fails at devm_clk_rate_exclusive_get() or clk_get_rate(),
> which occur before runtime PM is initialized, the clocks enabled by
> clk_bulk_prepare_enable() are never disabled.
>
> When probe fails after runtime PM is initialized, the previous error
> path called pm_runtime_put_sync(), which triggers the runtime suspend
> callback. However, due to different clock management strategies on
> different SoCs[1] (to avoid deadlocks between the global prepare_lock
> and runtime PM), the callback may only disable clocks without
> unpreparing them, causing an incomplete unwind.
>
> Introduce a new error label 'clk_disable' to explicitly invoke
> clk_bulk_disable_unprepare(). Replace pm_runtime_put_sync() with the
> sequence of pm_runtime_disable(), pm_runtime_set_suspended() and
> pm_runtime_put_noidle() to bypass the runtime suspend callback during
> error recovery. During the LPI2C driver probe phase, clock APIs are
> used exclusively to manage clocks. Once probing succeeds, clock
> management is handed over to the runtime PM core.
>
> [1] https://lore.kernel.org/all/20251125084718.2156168-1-carlos.song@xxxxxxx/
>
> Signed-off-by: Carlos Song <carlos.song@xxxxxxx>
> ---

In future, we need work with community to fix clock framework global lock
problem. Any this one is good for now.

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  drivers/i2c/busses/i2c-imx-lpi2c.c | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
> index e6c24a9d934d..2dc4331ed796 100644
> --- a/drivers/i2c/busses/i2c-imx-lpi2c.c
> +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
> @@ -1527,14 +1527,19 @@ static int lpi2c_imx_probe(struct platform_device *pdev)
>  	 * each transfer
>  	 */
>  	ret = devm_clk_rate_exclusive_get(&pdev->dev, lpi2c_imx->clks[0].clk);
> -	if (ret)
> -		return dev_err_probe(&pdev->dev, ret,
> -				     "can't lock I2C peripheral clock rate\n");
> +	if (ret) {
> +		dev_err_probe(&pdev->dev, ret,
> +			      "can't lock I2C peripheral clock rate\n");
> +		goto clk_disable;
> +	}
>
>  	lpi2c_imx->rate_per = clk_get_rate(lpi2c_imx->clks[0].clk);
> -	if (!lpi2c_imx->rate_per)
> -		return dev_err_probe(&pdev->dev, -EINVAL,
> -				     "can't get I2C peripheral clock rate\n");
> +	if (!lpi2c_imx->rate_per) {
> +		ret = -EINVAL;
> +		dev_err_probe(&pdev->dev, ret,
> +			      "can't get I2C peripheral clock rate\n");
> +		goto clk_disable;
> +	}
>
>  	if (lpi2c_imx->hwdata->need_prepare_unprepare_clk)
>  		pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_LONG_TIMEOUT_MS);
> @@ -1576,8 +1581,11 @@ static int lpi2c_imx_probe(struct platform_device *pdev)
>
>  rpm_disable:
>  	pm_runtime_dont_use_autosuspend(&pdev->dev);
> -	pm_runtime_put_sync(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
> +	pm_runtime_set_suspended(&pdev->dev);
> +	pm_runtime_put_noidle(&pdev->dev);
> +clk_disable:
> +	clk_bulk_disable_unprepare(lpi2c_imx->num_clks, lpi2c_imx->clks);
>
>  	return ret;
>  }
> --
> 2.43.0
>