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SubjectRe: [PATCH v4 3/3] iio: adc: add support for Allwinner SoCs ADC
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On 04/09/2016 18:12, Peter Meerwald-Stadler wrote:
>
>> The Allwinner SoCs all have an ADC that can also act as a touchscreen
>> controller and a thermal sensor. This patch adds the ADC driver which is
>> based on the MFD for the same SoCs ADC.
>
> nitpicking ahead
>
[...]
>> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
>> new file mode 100644
>> index 0000000..a93d36d
>> --- /dev/null
>> +++ b/drivers/iio/adc/sun4i-gpadc-iio.c
>> @@ -0,0 +1,525 @@
>> +/* ADC driver for sunxi platforms' (A10, A13 and A31) GPADC
>> + *
>> + * Copyright (c) 2016 Quentin Schulz <quentin.schulz@free-electrons>
>
> email address is incomplete
>

As in my other patches, thanks!

>> + *
>> + * This program is free software; you can redistribute it and/or modify it under
>> + * the terms of the GNU General Public License version 2 as published by the
>> + * Free Software Foundation.
>> + *
>> + * The Allwinner SoCs all have an ADC that can also act as a touchscreen
>> + * controller and a thermal sensor.
>> + * The thermal sensor works only when the ADC acts as a touchscreen controller
>> + * and is configured to throw an interrupt every fixed periods of time (let say
>> + * every X seconds).
>> + * One would be tempted to disable the IP on the hardware side rather than
>> + * disabling interrupts to save some power but that reset the internal clock of
>
> resets
>
>> + * the IP, resulting in having to wait X seconds every time we want to read the
>> + * value of the thermal sensor.
>> + * This is also the reason of using autosuspend in pm_runtime. If there were no
>
> there was no
>
[...]
>> +
>> +const unsigned int sun4i_gpadc_chan_select(unsigned int chan)
>
> static instead of const?
>

static const then?

>> +{
>> + return SUN4I_GPADC_CTRL1_ADC_CHAN_SELECT(chan);
>> +}
>> +
>> +const unsigned int sun6i_gpadc_chan_select(unsigned int chan)
>
> static instead of const?
>

static const then?

>> +{
>> + return SUN6I_GPADC_CTRL1_ADC_CHAN_SELECT(chan);
>> +}
>> +
>> +struct soc_specific {
>> + const int temp_offset;
>
> wondering why you constify every member?
>

Because they're supposed to be fixed values? It won't change in runtime.
Is there any reason why I shouldn't do that?

>> + const int temp_scale;
>> + const unsigned int tp_mode_en;
>> + const unsigned int tp_adc_select;
>> + const unsigned int (*adc_chan_select)(unsigned int chan);
>> +};
[...]
>> +static int sun4i_gpadc_read(struct iio_dev *indio_dev, int channel, int *val,
>> + unsigned int irq)
>> +{
>> + struct sun4i_gpadc_dev *info = iio_priv(indio_dev);
>> + int ret = 0;
>> +
>> + pm_runtime_get_sync(indio_dev->dev.parent);
>> + mutex_lock(&info->mutex);
>> +
>> + reinit_completion(&info->completion);
>> +
>> + regmap_write(info->regmap, SUN4I_GPADC_INT_FIFOC,
>> + SUN4I_GPADC_INT_FIFOC_TP_FIFO_TRIG_LEVEL(1) |
>> + SUN4I_GPADC_INT_FIFOC_TP_FIFO_FLUSH);
>
> check retval? here and elsewhere for regmap_write()
>

ACK. What should I do with the retval then?

There are some in:
- sun4i_gpadc_read called for read_raws => return which error code (or
-ret only?)?
- sun4i_gpadc_runtime_suspend => return value of ret, but that would
cancel the suspend right?
- sun4i_gpadc_runtime_resume => return value of ret, but that would
cancel resume right?
- sun4i_gpadc_probe in the error gotos => probe already failing so do we
actually care if regmap_update_bits fails? If yes, what's the expected
behaviour?
- sun4i_gpadc_remove => return value of ret, but that would mean the
remove failed right?

[...]
>> +static int sun4i_gpadc_read_raw(struct iio_dev *indio_dev,
>> + struct iio_chan_spec const *chan, int *val,
>> + int *val2, long mask)
>> +{
>> + int ret;
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_OFFSET:
>> + ret = sun4i_gpadc_temp_offset(indio_dev, val);
>> + if (ret)
>> + return ret;
>> +
>> + return IIO_VAL_INT;
>> + case IIO_CHAN_INFO_RAW:
>> + if (chan->type == IIO_VOLTAGE) {
>> + ret = sun4i_gpadc_adc_read(indio_dev, chan->channel,
>> + val);
>> + if (ret)
>> + return ret;
>
> could share the "if (ret) return ret;" between code path
>

ACK.

[...]
>> +static int sun4i_irq_init(struct platform_device *pdev, const char *name,
>> + irq_handler_t handler, const char *devname,
>> + unsigned int *irq, atomic_t *atomic)
>> +{
>> + int ret;
>> + struct sun4i_gpadc_mfd_dev *mfd_dev = dev_get_drvdata(pdev->dev.parent);
>> + struct sun4i_gpadc_dev *info = iio_priv(dev_get_drvdata(&pdev->dev));
>> +
>> + /*
>> + * Once the interrupt is activated, the IP continuously performs
>> + * conversions thus throws interrupts. The interrupt is activated right
>> + * after being requested but we want to control when these interrupts
>> + * occurs thus we disable it right after being requested. However, an
>
> occur
>

ACK for all typos.
Thanks!

Quentin

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