iio: adc: ti-tlc4541: Fix alignment for DMA safety

[ Upstream commit 62fa19bf484bfeb52c56b7c6d6a6b1222c597f9c ]

____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: ac2bec9d587c ("iio: adc: tlc4541: add support for TI tlc4541 adc")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220508175712.647246-40-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iio/adc/ti-tlc4541.c b/drivers/iio/adc/ti-tlc4541.c
index 2406eda9dfc6ab7357b7a33f4e89e8892ff97747..30f629a553a14e991ec949f2b1a93fb7d672070b 100644 (file)
--- a/drivers/iio/adc/ti-tlc4541.c
+++ b/drivers/iio/adc/ti-tlc4541.c
@@ -37,12 +37,12 @@ struct tlc4541_state {
        struct spi_message              scan_single_msg;
 
        /*
-        * DMA (thus cache coherency maintenance) requires the
+        * DMA (thus cache coherency maintenance) may require the
         * transfer buffers to live in their own cache lines.
         * 2 bytes data + 6 bytes padding + 8 bytes timestamp when
         * call iio_push_to_buffers_with_timestamp.
         */
-       __be16                          rx_buf[8] ____cacheline_aligned;
+       __be16                          rx_buf[8] __aligned(IIO_DMA_MINALIGN);
 };
 
 struct tlc4541_chip_info {