Re: [PATCH v6 07/17] iio: adc: at91-sama5d2_adc: adapt the driver for sama7d65

[Jonathan Cameron <jic23@kernel.org>]

On Sat, 15 Aug 2026 21:21:13 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> On Thu, 6 Aug 2026 13:10:14 +0530
> Varshini Rajendran <varshini.rajendran@microchip.com> wrote:
> 
> > Add support for sama7d65 ADC. The differences are highlighted with the
> > compatible. The calibration data layout is the main difference.
> > 
> > Update Kconfig help text to mention SAMA7 SoC family support.
> > 
> > Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com>  
> 
> The Sashiko feedback on this one is interesting.
> 
> https://sashiko.dev/#/patchset/20260806074024.531259-1-varshini.rajendran%40microchip.com
> 
> The timestamp in the chan_spec array isn't the last one - the
> timestamp comes after it which is going to break in various
> unhelpful ways - as iio_push_to_buffers_with_timestamp() requires
> the timestamp to be the last scan index.
> 
> in at91_adc_trigger_handler_nodma() there is a comment saying
> that it can only be used with voltage channels. That's fine but
> if they aren't useful, why are the scan_index values not -1
> which is how we hide those interfaces for channels for which
> buffered capture is not supported.
> 
> Given you have the hardware set up, can you check if the
> scan_elements/*_en is there for the temp channel and
> that for cases where it is enabled, we get an error in the
> buffer preenable callback?
> 
> So I think it's a false positive but fair enough given the
> current user interfaces seems likely to be rather odd.
> 
> Please sanity check all this.
This is still open.  I'm going to mark the series as expecting
a new version in patchwork as it's been sitting a while without
activity and loose track of status after a week or two!

Jonathan
> 
> One other thing inline.
> 
> Jonathan
> 
> 
> > ---
> >  drivers/iio/adc/Kconfig            |  2 +-
> >  drivers/iio/adc/at91-sama5d2_adc.c | 30 ++++++++++++++++++++++++++++++
> >  2 files changed, 31 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 3755a81c1efd..85b443853a08 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -647,7 +647,7 @@ config AT91_SAMA5D2_ADC
> >  	select IIO_TRIGGERED_BUFFER
> >  	help
> >  	  Say yes here to build support for Atmel SAMA5D2 ADC which is
> > -	  available on SAMA5D2 SoC family.
> > +	  available on SAMA5D2 and SAMA7 SoC families.
> >  
> >  	  To compile this driver as a module, choose M here: the module will be
> >  	  called at91-sama5d2_adc.
> > diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> > index 3e9feb824a66..c1e5139a058c 100644
> > --- a/drivers/iio/adc/at91-sama5d2_adc.c
> > +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> > @@ -528,6 +528,15 @@ static const struct at91_adc_temp_calib_layout sama7g5_temp_calib = {
> >  	.p1_scale = { .numerator = 1000, .denominator = 1 },
> >  };
> >  
> > +static const struct at91_adc_temp_calib_layout sama7d65_temp_calib = {
> > +	.tag_idx = 1,
> > +	.p1_idx = 3,
> > +	.p4_idx = 2,
> > +	.p6_idx = 5,
> > +	.min_len = 11,
> > +	.p1_scale = { .numerator = 1, .denominator = 1000 },
> > +};
> > +
> >  /* Temperature sensor calibration - Vtemp voltage sensitivity to temperature. */
> >  #define AT91_ADC_TS_VTEMP_DT		(2080U)
> >  
> > @@ -766,6 +775,24 @@ static const struct at91_adc_platform sama7g5_platform = {
> >  	.temp_calib_layout = &sama7g5_temp_calib,
> >  };
> >  
> > +static const struct at91_adc_platform sama7d65_platform = {
> > +	.layout = &sama7g5_layout,
> > +	.adc_channels = &at91_sama7g5_adc_channels,
> > +	.nr_channels = AT91_SAMA7G5_SINGLE_CHAN_CNT +
> > +		       AT91_SAMA7G5_DIFF_CHAN_CNT +
> > +		       AT91_SAMA7G5_TEMP_CHAN_CNT,
> > +	.max_channels = ARRAY_SIZE(at91_sama7g5_adc_channels),
> > +	.max_index = AT91_SAMA7G5_MAX_CHAN_IDX,
> > +	.hw_trig_cnt = AT91_SAMA7G5_HW_TRIG_CNT,
> > +	.osr_mask = GENMASK(18, 16),
> > +	.oversampling_avail = { 1, 4, 16, 64, 256 },
> > +	.oversampling_avail_no = 5,
> > +	.chan_realbits = 16,
> > +	.temp_sensor = true,
> > +	.temp_chan = AT91_SAMA7G5_ADC_TEMP_CHANNEL,  
> Is this ever used?
> 
> > +	.temp_calib_layout = &sama7d65_temp_calib,
> > +};
> > +
> >  static int at91_adc_chan_xlate(struct iio_dev *indio_dev, int chan)
> >  {
> >  	int i;
> > @@ -2632,6 +2659,9 @@ static const struct of_device_id at91_adc_dt_match[] = {
> >  	}, {
> >  		.compatible = "microchip,sama7g5-adc",
> >  		.data = &sama7g5_platform,
> > +	}, {
> > +		.compatible = "microchip,sama7d65-adc",
> > +		.data = &sama7d65_platform,
> >  	}, {
> >  		/* sentinel */
> >  	}  
> 
>