[PATCH 6.1 0722/1146] iio: temperature: ltc2983: make bulk write buffer DMA-safe

Greg Kroah-Hartman
2022-12-28T16:29:08Z

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 a60ccf183687..1117991ca2ab 100644
--- a/drivers/iio/temperature/ltc2983.c
+++ b/drivers/iio/temperature/ltc2983.c
@@ -209,6 +209,7 @@ struct ltc2983_data {
* Holds the converted temperature
*/
__be32 temp __aligned(IIO_DMA_MINALIGN);
+ __be32 chan_val;
};

struct ltc2983_sensor {
@@ -313,19 +314,18 @@ 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