iio: adc: ltc2497: Fix alignment for DMA safety

[ Upstream commit 6ebf401d555ee1e75e779b865d38e171db0aa1f2 ]

____cacheline_aligned is an insufficient guarantee for non-coherent DMA
on platforms with 128 byte cachelines above L1.  Switch to the updated
IIO_DMA_MINALIGN definition.

Update the comment to include 'may'.

Fixes: bc82222fcca1 ("iio:adc: Driver for Linear Technology LTC2497 ADC")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-23-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c
index 1adddf5a88a94b0a2ae4284e1cf4033ce11fdc2c..f7c786f37ceb141743bf2990dc80e7a0b2c206a3 100644 (file)
--- a/drivers/iio/adc/ltc2497.c
+++ b/drivers/iio/adc/ltc2497.c
@@ -20,10 +20,10 @@ struct ltc2497_driverdata {
        struct ltc2497core_driverdata common_ddata;
        struct i2c_client *client;
        /*
-        * DMA (thus cache coherency maintenance) requires the
+        * DMA (thus cache coherency maintenance) may require the
         * transfer buffers to live in their own cache lines.
         */
-       __be32 buf ____cacheline_aligned;
+       __be32 buf __aligned(IIO_DMA_MINALIGN);
 };
 
 static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,