linux-kernel - [PATCH 08/10] iio: adc: ti-ads124s08: use struct with aligned

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Message-Id: <20250418-iio-prefer-aligned_s64-timestamp-v1-8-4c6080710516@baylibre.com>
Date: Fri, 18 Apr 2025 14:58:27 -0500
From: David Lechner <dlechner@...libre.com>
To: Jonathan Cameron <jic23@...nel.org>, 
 Nuno Sá <nuno.sa@...log.com>, 
 Andy Shevchenko <andy@...nel.org>, Eugen Hristev <eugen.hristev@...aro.org>, 
 Nicolas Ferre <nicolas.ferre@...rochip.com>, 
 Alexandre Belloni <alexandre.belloni@...tlin.com>, 
 Claudiu Beznea <claudiu.beznea@...on.dev>, 
 Andreas Klinger <ak@...klinger.de>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, 
 Maxime Coquelin <mcoquelin.stm32@...il.com>, 
 Alexandre Torgue <alexandre.torgue@...s.st.com>
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, imx@...ts.linux.dev, 
 linux-stm32@...md-mailman.stormreply.com, 
 David Lechner <dlechner@...libre.com>
Subject: [PATCH 08/10] iio: adc: ti-ads124s08: use struct with aligned_s64
 timestamp

Use a struct with aligned s64_timestamp instead of a padded array for
the buffer used for iio_push_to_buffers_with_ts(). This makes it easier
to see the correctness of the size and alignment of the buffer.

Signed-off-by: David Lechner <dlechner@...libre.com>
---
 drivers/iio/adc/ti-ads124s08.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/iio/adc/ti-ads124s08.c b/drivers/iio/adc/ti-ads124s08.c
index 8ea1269f74db09427a4a8d434ba1d63e7c63d038..ecaffe83fcc911f99afbeae7ef51440d150bef73 100644
--- a/drivers/iio/adc/ti-ads124s08.c
+++ b/drivers/iio/adc/ti-ads124s08.c
@@ -98,14 +98,10 @@ struct ads124s_private {
 	struct gpio_desc *reset_gpio;
 	struct spi_device *spi;
 	struct mutex lock;
-	/*
-	 * Used to correctly align data.
-	 * Ensure timestamp is naturally aligned.
-	 * Note that the full buffer length may not be needed if not
-	 * all channels are enabled, as long as the alignment of the
-	 * timestamp is maintained.
-	 */
-	u32 buffer[ADS124S08_MAX_CHANNELS + sizeof(s64)/sizeof(u32)] __aligned(8);
+	struct {
+		u32 data[ADS124S08_MAX_CHANNELS];
+		aligned_s64 timestamp;
+	} buffer;
 	u8 data[5] __aligned(IIO_DMA_MINALIGN);
 };
 
@@ -289,7 +285,7 @@ static irqreturn_t ads124s_trigger_handler(int irq, void *p)
 		if (ret)
 			dev_err(&priv->spi->dev, "Start ADC conversions failed\n");
 
-		priv->buffer[j] = ads124s_read(indio_dev);
+		priv->buffer.data[j] = ads124s_read(indio_dev);
 		ret = ads124s_write_cmd(indio_dev, ADS124S08_STOP_CONV);
 		if (ret)
 			dev_err(&priv->spi->dev, "Stop ADC conversions failed\n");
@@ -297,8 +293,8 @@ static irqreturn_t ads124s_trigger_handler(int irq, void *p)
 		j++;
 	}
 
-	iio_push_to_buffers_with_ts(indio_dev, priv->buffer, sizeof(priv->buffer),
-				    pf->timestamp);
+	iio_push_to_buffers_with_ts(indio_dev, &priv->buffer,
+				    sizeof(priv->buffer), pf->timestamp);
 
 	iio_trigger_notify_done(indio_dev->trig);
 

-- 
2.43.0