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[v2,29/92] iio: adc: ti-adc084s021: Fix alignment for DMA safety

Message ID 20220508175712.647246-30-jic23@kernel.org (mailing list archive)
State Accepted
Headers show
Series IIO: Fix alignment of buffers for DMA | expand

Commit Message

Jonathan Cameron May 8, 2022, 5:56 p.m. UTC
From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

____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: 3691e5a69449 ("iio: adc: add driver for the ti-adc084s021 chip")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Mårten Lindahl <martenli@axis.com>
Acked-by: Nuno Sá <nuno.sa@analog.com>
---
 drivers/iio/adc/ti-adc084s021.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Marten Lindahl May 9, 2022, 8:34 a.m. UTC | #1
On Sun, May 08, 2022 at 07:56:09PM +0200, Jonathan Cameron wrote:
> From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> 
> ____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: 3691e5a69449 ("iio: adc: add driver for the ti-adc084s021 chip")
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Cc: Mårten Lindahl <martenli@axis.com>
> Acked-by: Nuno Sá <nuno.sa@analog.com>

Acked-by: Mårten Lindahl <marten.lindahl@axis.com>

> ---
>  drivers/iio/adc/ti-adc084s021.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ti-adc084s021.c b/drivers/iio/adc/ti-adc084s021.c
> index c9b5d9aec3dc..1f6e53832e06 100644
> --- a/drivers/iio/adc/ti-adc084s021.c
> +++ b/drivers/iio/adc/ti-adc084s021.c
> @@ -32,10 +32,10 @@ struct adc084s021 {
>  		s64 ts __aligned(8);
>  	} scan;
>  	/*
> -	 * DMA (thus cache coherency maintenance) requires the
> +	 * DMA (thus cache coherency maintenance) may require the
>  	 * transfer buffers to live in their own cache line.
>  	 */
> -	u16 tx_buf[4] ____cacheline_aligned;
> +	u16 tx_buf[4] __aligned(IIO_DMA_MINALIGN);
>  	__be16 rx_buf[5]; /* First 16-bits are trash */
>  };
>  
> -- 
> 2.36.0
>
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Patch

diff --git a/drivers/iio/adc/ti-adc084s021.c b/drivers/iio/adc/ti-adc084s021.c
index c9b5d9aec3dc..1f6e53832e06 100644
--- a/drivers/iio/adc/ti-adc084s021.c
+++ b/drivers/iio/adc/ti-adc084s021.c
@@ -32,10 +32,10 @@  struct adc084s021 {
 		s64 ts __aligned(8);
 	} scan;
 	/*
-	 * DMA (thus cache coherency maintenance) requires the
+	 * DMA (thus cache coherency maintenance) may require the
 	 * transfer buffers to live in their own cache line.
 	 */
-	u16 tx_buf[4] ____cacheline_aligned;
+	u16 tx_buf[4] __aligned(IIO_DMA_MINALIGN);
 	__be16 rx_buf[5]; /* First 16-bits are trash */
 };