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From: Andy Shevchenko <andriy.shevchenko@intel.com>
To: David Lechner <dlechner@baylibre.com>
Cc: "Jonathan Cameron" <jic23@kernel.org>,
	"Nuno Sá" <nuno.sa@analog.com>,
	"Andy Shevchenko" <andy@kernel.org>,
	"Matt Ranostay" <mranostay@gmail.com>,
	linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] iio: adc: ti-adc161s626: fix buffer read on big-endian
Date: Mon, 16 Mar 2026 15:56:26 +0200	[thread overview]
Message-ID: <abgMCgp8JIUigQLq@ashevche-desk.local> (raw)
In-Reply-To: <20260314-iio-adc-ti-adc161s626-fix-scan-buf-v1-1-56243b11e87b@baylibre.com>

On Sat, Mar 14, 2026 at 06:13:31PM -0500, David Lechner wrote:
> Rework ti_adc_trigger_handler() to properly handle data on big-endian
> architectures. The scan data format is 16-bit CPU-endian, so we can't
> cast it to a int * on big-endian and expect it to work. Instead, we
> introduce a local int variable to read the data into, and then copy it
> to the buffer.
> 
> Since the buffer isn't passed to any SPI functions, we don't need it to
> be DMA-safe. So we can drop it from the driver data struct and just
> use stack memory for the scan data.
> 
> Since there is only one data value (plus timestamp), we don't need an
> array and can just declare a struct with the correct data type instead.
> 
> Also fix alignment of iio_get_time_ns() to ( while we are touching this.

...

>  	struct iio_poll_func *pf = private;
>  	struct iio_dev *indio_dev = pf->indio_dev;
>  	struct ti_adc_data *data = iio_priv(indio_dev);

> +	int ret, val;

Can this be put after the 'scan'?

> +	struct {
> +		s16 data;
> +		aligned_s64 timestamp;
> +	} scan = { };
> +
> +	ret = ti_adc_read_measurement(data, &indio_dev->channels[0], &val);

> +	if (!ret) {

Personally I prefer goto approach over unusual pattern and TAB indentation.

> +		scan.data = val;
> +		iio_push_to_buffers_with_timestamp(indio_dev, &scan,
> +						   iio_get_time_ns(indio_dev));
> +	}
>  
> +	ret = ti_adc_read_measurement(data, &indio_dev->channels[0], &val);

	if (ret)
		goto exit_notify_done;

	scan.data = val;
	// Also can we consider moving towards new API?
	iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev));

exit_notify_done:

>  	iio_trigger_notify_done(indio_dev->trig);

-- 
With Best Regards,
Andy Shevchenko



  reply	other threads:[~2026-03-16 13:57 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-14 23:13 [PATCH 0/2] iio: adc: ti-adc161s626: fix scan buffer handling David Lechner
2026-03-14 23:13 ` [PATCH 1/2] iio: adc: ti-adc161s626: fix buffer read on big-endian David Lechner
2026-03-16 13:56   ` Andy Shevchenko [this message]
2026-03-21 20:42     ` Jonathan Cameron
2026-03-14 23:13 ` [PATCH 2/2] iio: adc: ti-adc161s626: use DMA-safe memory for spi_read() David Lechner
2026-03-16 14:05   ` Andy Shevchenko
2026-03-21 20:45     ` Jonathan Cameron
2026-03-16 18:31   ` Jonathan Cameron
2026-03-16 19:53     ` Andy Shevchenko
2026-03-21 19:40       ` David Lechner
2026-03-21 20:54         ` Jonathan Cameron
2026-03-21 20:18       ` Jonathan Cameron
2026-03-21 19:27     ` David Lechner
2026-03-21 20:21       ` Jonathan Cameron
2026-03-27  9:13   ` kernel test robot
2026-03-27  9:44     ` Andy Shevchenko
2026-03-27 13:54       ` David Lechner

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