Re: [PATCH v4 1/3] iio: adc: add imx93 adc support

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 26 Dec 2022 12:27:17 +0800
haibo.chen@nxp.com wrote:

> From: Haibo Chen <haibo.chen@nxp.com>
> 
> The ADC in i.mx93 is a total new ADC IP, add a driver to support
> this ADC.
> 
> Currently, only support one shot normal conversion triggered by
> software. For other mode, will add in future.
> 
> Signed-off-by: Haibo Chen <haibo.chen@nxp.com>

Hi Haibo,

I think there are still improvements to be made in ordering in probe()/remove()
and also you aren't calling pm_runtime_dont_use_autosuspend()
which is a requirement if manually handling runtime pm disabling on remove()

Jonathan

> ---
>
> diff --git a/drivers/iio/adc/imx93_adc.c b/drivers/iio/adc/imx93_adc.c
> new file mode 100644
> index 000000000000..677f13a040f8
> --- /dev/null
> +++ b/drivers/iio/adc/imx93_adc.c
> @@ -0,0 +1,477 @@



> +static int imx93_adc_probe(struct platform_device *pdev)
> +{
> +	struct imx93_adc *adc;
> +	struct iio_dev *indio_dev;
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
> +	if (!indio_dev) {
> +		dev_err(dev, "Failed allocating iio device\n");
> +		return -ENOMEM;
> +	}
> +
> +	adc = iio_priv(indio_dev);
> +	adc->dev = dev;
> +
> +	mutex_init(&adc->lock);
> +	adc->regs = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(adc->regs))
> +		return PTR_ERR(adc->regs);
> +
> +	/* The third irq is for ADC conversion usage */
> +	adc->irq = platform_get_irq(pdev, 2);
> +	if (adc->irq < 0)
> +		return adc->irq;
> +
> +	adc->ipg_clk = devm_clk_get(dev, "ipg");
> +	if (IS_ERR(adc->ipg_clk))
> +		return dev_err_probe(dev, PTR_ERR(adc->ipg_clk),
> +				     "Failed getting clock.\n");
> +
> +	adc->vref = devm_regulator_get(dev, "vref");
> +	if (IS_ERR(adc->vref))
> +		return dev_err_probe(dev, PTR_ERR(adc->vref),
> +				     "Failed getting reference voltage.\n");
> +
> +	ret = regulator_enable(adc->vref);
> +	if (ret) {
> +		dev_err(dev, "Can't enable adc reference top voltage.\n");

You can use dev_err_probe() for all such handling in probe() whether or not
it can defer.  That tends to simplify things and avoids the need for reviewers
to consider if a function can defer of not.

> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	init_completion(&adc->completion);
> +
> +	indio_dev->name = "imx93-adc";
> +	indio_dev->info = &imx93_adc_iio_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = imx93_adc_iio_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(imx93_adc_iio_channels);
> +
> +	ret = clk_prepare_enable(adc->ipg_clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Could not prepare or enable the clock.\n");
> +		goto error_regulator_disable;
> +	}
> +
> +	ret = request_irq(adc->irq, imx93_adc_isr, 0, IMX93_ADC_DRIVER_NAME, adc);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed requesting irq, irq = %d\n", adc->irq);
> +		goto error_ipg_clk_disable;
> +	}
> +
> +	ret = imx93_adc_calibration(adc);
> +	if (ret < 0)
> +		goto error_free_adc_irq;
> +
> +	imx93_adc_config_ad_clk(adc);
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret) {
> +		dev_err(dev, "Couldn't register the device.\n");
> +		goto error_free_adc_irq;
> +	}
> +
> +	pm_runtime_set_active(dev);
> +	pm_runtime_set_autosuspend_delay(dev, 50);
> +	pm_runtime_use_autosuspend(dev);
> +	pm_runtime_enable(dev);
> +
> +	return 0;
> +
> +error_free_adc_irq:
> +	free_irq(adc->irq, adc);
> +error_ipg_clk_disable:
> +	clk_disable_unprepare(adc->ipg_clk);
> +error_regulator_disable:
> +	regulator_disable(adc->vref);
> +
> +	return ret;
> +}
> +
> +static int imx93_adc_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct imx93_adc *adc = iio_priv(indio_dev);
> +	struct device *dev = adc->dev;
> +
> +	/* adc power down need clock on */
> +	pm_runtime_get_sync(dev);
> +
> +	iio_device_unregister(indio_dev);
> +	imx93_adc_power_down(adc);

Why is there no similar power down in the error path in probe for
iio_device_register() returning an error?

> +	free_irq(adc->irq, adc);
> +	clk_disable_unprepare(adc->ipg_clk);
> +	regulator_disable(adc->vref);
> +
> +	pm_runtime_disable(dev);
> +	pm_runtime_put_noidle(dev);

I think I caused confusion a bit here by pointing out the device unregister
needed to be first. That's now fine, but the rest would benefit from a rethink.
To my mind, the ideal situation is that the remove() is a reverse of the probe()
function, so I'd expect to see these pm_runtime_disable(), pm_runtime_put_noidle()
at the start of this
function.  Note that you also need to call pm_runtime_dont_use_autosuspend() somewhere
in here - or take all the probe/remove devm_ managed and use
devm_pm_runtime_enable() which tidies that up for you as needed.
(see docs in pm_runtime.h)

> +
> +	return 0;
> +}