FAILED: patch "[PATCH] iio: adc: ti-adc161s626: use DMA-safe memory for spi_read()" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 768461517a28d80fe81ea4d5d03a90cd184ea6ad
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026040713-crescent-angles-fabe@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 768461517a28d80fe81ea4d5d03a90cd184ea6ad Mon Sep 17 00:00:00 2001
From: David Lechner <[email protected]>
Date: Sat, 14 Mar 2026 18:13:32 -0500
Subject: [PATCH] iio: adc: ti-adc161s626: use DMA-safe memory for spi_read()

Add a DMA-safe buffer and use it for spi_read() instead of a stack memory. All SPI buffers must be DMA-safe.

Since we only need up to 3 bytes, we just use a u8[] instead of __be16 and __be32 and change the conversion functions appropriately.

index 42968d96572b..be1cc2e77862 100644
@@ -15,6 +15,7 @@
 #include <linux/init.h>
 #include <linux/err.h>
 #include <linux/spi/spi.h>
+#include <linux/unaligned.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/trigger.h>
 #include <linux/iio/buffer.h>

@@ -70,6 +71,7 @@ struct ti_adc_data {
 
 	u8 read_size;
 	u8 shift;
+	u8 buf[3] __aligned(IIO_DMA_MINALIGN);
 };
 
 static int ti_adc_read_measurement(struct ti_adc_data *data,

@@ -78,26 +80,20 @@ static int ti_adc_read_measurement(struct ti_adc_data *data,
 	int ret;
 
 	switch (data->read_size) {
-	case 2: {
-		__be16 buf;
-
-		ret = spi_read(data->spi, (void *) &buf, 2);
+	case 2:
+		ret = spi_read(data->spi, data->buf, 2);
 		if (ret)
 			return ret;
 
-		*val = be16_to_cpu(buf);
+		*val = get_unaligned_be16(data->buf);
 		break;
-	}
-	case 3: {
-		__be32 buf;
-
-		ret = spi_read(data->spi, (void *) &buf, 3);
+	case 3:
+		ret = spi_read(data->spi, data->buf, 3);
 		if (ret)
 			return ret;
 
-		*val = be32_to_cpu(buf) >> 8;
+		*val = get_unaligned_be24(data->buf);
 		break;
-	}
 	default:
 		return -EINVAL;
 	}