releases/5.15.86/iio-temperature-ltc2983-make-bulk-write-buffer-dma-s.patch

From 16d03892d157b7be9edc29c8b19c6863c70766a6 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Thu, 3 Nov 2022 15:00:29 +0200
Subject: iio: temperature: ltc2983: make bulk write buffer DMA-safe

From: Cosmin Tanislav <cosmin.tanislav@analog.com>

[ Upstream commit 5e0176213949724fbe9a8e4a39817edce337b8a0 ]

regmap_bulk_write() does not guarantee implicit DMA-safety,
even though the current implementation duplicates the given
buffer. Do not rely on it.

Fixes: f110f3188e56 ("iio: temperature: Add support for LTC2983")
Signed-off-by: Cosmin Tanislav <cosmin.tanislav@analog.com>
Link: https://lore.kernel.org/r/20221103130041.2153295-2-demonsingur@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iio/temperature/ltc2983.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/temperature/ltc2983.c b/drivers/iio/temperature/ltc2983.c
index 8306daa77908..b2ae2d2c7eef 100644
--- a/drivers/iio/temperature/ltc2983.c
+++ b/drivers/iio/temperature/ltc2983.c
@@ -205,6 +205,7 @@ struct ltc2983_data {
 	 * Holds the converted temperature
 	 */
 	__be32 temp ____cacheline_aligned;
+	__be32 chan_val;
 };
 
 struct ltc2983_sensor {
@@ -309,19 +310,18 @@ static int __ltc2983_fault_handler(const struct ltc2983_data *st,
 	return 0;
 }
 
-static int __ltc2983_chan_assign_common(const struct ltc2983_data *st,
+static int __ltc2983_chan_assign_common(struct ltc2983_data *st,
 					const struct ltc2983_sensor *sensor,
 					u32 chan_val)
 {
 	u32 reg = LTC2983_CHAN_START_ADDR(sensor->chan);
-	__be32 __chan_val;
 
 	chan_val |= LTC2983_CHAN_TYPE(sensor->type);
 	dev_dbg(&st->spi->dev, "Assign reg:0x%04X, val:0x%08X\n", reg,
 		chan_val);
-	__chan_val = cpu_to_be32(chan_val);
-	return regmap_bulk_write(st->regmap, reg, &__chan_val,
-				 sizeof(__chan_val));
+	st->chan_val = cpu_to_be32(chan_val);
+	return regmap_bulk_write(st->regmap, reg, &st->chan_val,
+				 sizeof(st->chan_val));
 }
 
 static int __ltc2983_chan_custom_sensor_assign(struct ltc2983_data *st,
-- 
2.35.1