On Fri, 3 Jan 2025 at 15:00, Claudiu <claudiu.beznea@xxxxxxxxx> wrote:
>
> From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
>
> On all systems where the rzg2l_adc driver is used, the ADC clocks are part
> of a PM domain. The code that implements the PM domains support is in
> drivers/clk/renesas/rzg2l-cpg.c, the functions of interest for this commit
> being rzg2l_cpg_attach_dev() and rzg2l_cpg_deattach_dev(). The PM
> domains support is registered with GENPD_FLAG_PM_CLK which, according to
> the documentation, instructs genpd to use the PM clk framework while
> powering on/off attached devices.
>
> During probe, the ADC device is attached to the PM domain
> controlling the ADC clocks. Similarly, during removal, the ADC device is
> detached from the PM domain.
>
> The detachment call stack is as follows:
>
> device_driver_detach() ->
> device_release_driver_internal() ->
> __device_release_driver() ->
> device_remove() ->
> platform_remove() ->
> dev_pm_domain_detach()
>
> During driver unbind, after the ADC device is detached from its PM domain,
> the device_unbind_cleanup() function is called, which subsequently invokes
> devres_release_all(). This function handles devres resource cleanup.
>
> If runtime PM is enabled via devm_pm_runtime_enable(), the cleanup process
> triggers the action or reset function for disabling runtime PM. This
> function is pm_runtime_disable_action(), which leads to the following call
> stack of interest when called:
>
> pm_runtime_disable_action() ->
> pm_runtime_dont_use_autosuspend() ->
> __pm_runtime_use_autosuspend() ->
> update_autosuspend() ->
> rpm_idle()
>
> The rpm_idle() function attempts to runtime resume the ADC device. However,
> at the point it is called, the ADC device is no longer part of the PM
> domain (which manages the ADC clocks). Since the rzg2l_adc runtime PM
> APIs directly modifies hardware registers, the
> rzg2l_adc_pm_runtime_resume() function is invoked without the ADC clocks
> being enabled. This is because the PM domain no longer resumes along with
> the ADC device. As a result, this leads to system aborts.
>
> Drop the devres API for runtime PM enable.
>
> Fixes: 89ee8174e8c8 ("iio: adc: rzg2l_adc: Simplify the runtime PM code")
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Kind regards
Uffe
> ---
> drivers/iio/adc/rzg2l_adc.c | 33 ++++++++++++++++++++++++---------
> 1 file changed, 24 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iio/adc/rzg2l_adc.c b/drivers/iio/adc/rzg2l_adc.c
> index 883c167c0670..f12f3daf08cc 100644
> --- a/drivers/iio/adc/rzg2l_adc.c
> +++ b/drivers/iio/adc/rzg2l_adc.c
> @@ -464,25 +464,26 @@ static int rzg2l_adc_probe(struct platform_device *pdev)
>
> pm_runtime_set_autosuspend_delay(dev, 300);
> pm_runtime_use_autosuspend(dev);
> - ret = devm_pm_runtime_enable(dev);
> - if (ret)
> - return ret;
> + pm_runtime_enable(dev);
>
> platform_set_drvdata(pdev, indio_dev);
>
> ret = rzg2l_adc_hw_init(dev, adc);
> - if (ret)
> - return dev_err_probe(&pdev->dev, ret,
> - "failed to initialize ADC HW\n");
> + if (ret) {
> + dev_err_probe(&pdev->dev, ret, "failed to initialize ADC HW\n");
> + goto rpm_disable;
> + }
>
> irq = platform_get_irq(pdev, 0);
> - if (irq < 0)
> - return irq;
> + if (irq < 0) {
> + ret = irq;
> + goto rpm_disable;
> + }
>
> ret = devm_request_irq(dev, irq, rzg2l_adc_isr,
> 0, dev_name(dev), adc);
> if (ret < 0)
> - return ret;
> + goto rpm_disable;
>
> init_completion(&adc->completion);
>
> @@ -493,6 +494,19 @@ static int rzg2l_adc_probe(struct platform_device *pdev)
> indio_dev->num_channels = adc->data->num_channels;
>
> return devm_iio_device_register(dev, indio_dev);
> +
> +rpm_disable:
> + pm_runtime_disable(dev);
> + pm_runtime_dont_use_autosuspend(dev);
> + return ret;
> +}
> +
> +static void rzg2l_adc_remove(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> +
> + pm_runtime_disable(dev);
> + pm_runtime_dont_use_autosuspend(dev);
> }
>
> static const struct rzg2l_adc_hw_params rzg2l_hw_params = {
> @@ -614,6 +628,7 @@ static const struct dev_pm_ops rzg2l_adc_pm_ops = {
>
> static struct platform_driver rzg2l_adc_driver = {
> .probe = rzg2l_adc_probe,
> + .remove = rzg2l_adc_remove,
> .driver = {
> .name = DRIVER_NAME,
> .of_match_table = rzg2l_adc_match,
> --
> 2.43.0
>
