linux-kernel - Re: [PATCH for-5.9] iio: adc: meson-saradc: Use the parent device to look up the calib data

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Message-ID: <20200822114036.49199bff@archlinux>
Date:   Sat, 22 Aug 2020 11:40:36 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     lars@...afoo.de, linux-iio@...r.kernel.org,
        linux-amlogic@...ts.infradead.org, knaack.h@....de,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH for-5.9] iio: adc: meson-saradc: Use the parent device
 to look up the calib data

On Sat, 15 Aug 2020 20:13:55 +0200
Martin Blumenstingl <martin.blumenstingl@...glemail.com> wrote:

> On the older-gen 32-bit SoCs the meson-saradc driver is used to read the
> SoC temperature. This requires reading calibration data from the eFuse.
> 
> Looking up the calibration data nvmem-cell requires the OF device_node
> pointer to be available in the struct device which is passed to
> devm_nvmem_cell_get(). This however got lost with commit 8cb631ccbb1952
> ("iio: Remove superfluous of_node assignments") from indio_dev->dev. As
> devm_nvmem_cell_get() is called in the initialization phase the
> device_node is not yet available because the NVMEM cell is looked up
> before iio_device_register() is called (which would then set the
> device_node automatically).
> Use the parent device to look up the NVMEM cell instead to fix this
> issue.
> 
> Fixes: 8cb631ccbb1952 ("iio: Remove superfluous of_node assignments")
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Gah.  I hope we don't have too many more non obvious cases like
this hiding.

Applied to the fixes-togreg branch of iio.git

Thanks,

Jonathan

> ---
>  drivers/iio/adc/meson_saradc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
> index 93c2252c0b89..1a9189ba69ae 100644
> --- a/drivers/iio/adc/meson_saradc.c
> +++ b/drivers/iio/adc/meson_saradc.c
> @@ -707,7 +707,7 @@ static int meson_sar_adc_temp_sensor_init(struct iio_dev *indio_dev)
>  	size_t read_len;
>  	int ret;
>  
> -	temperature_calib = devm_nvmem_cell_get(&indio_dev->dev,
> +	temperature_calib = devm_nvmem_cell_get(indio_dev->dev.parent,
>  						"temperature_calib");
>  	if (IS_ERR(temperature_calib)) {
>  		ret = PTR_ERR(temperature_calib);