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    Subject[PATCH 13/15] iio: core: Add support for cyclic buffers
    Date
    Introduce a new flag IIO_BUFFER_DMABUF_CYCLIC in the "flags" field of
    the iio_dmabuf uapi structure.

    When set, the DMABUF enqueued with the enqueue ioctl will be endlessly
    repeated on the TX output, until the buffer is disabled.

    Signed-off-by: Paul Cercueil <paul@crapouillou.net>
    ---
    drivers/iio/industrialio-buffer.c | 5 +++++
    include/uapi/linux/iio/buffer.h | 3 ++-
    2 files changed, 7 insertions(+), 1 deletion(-)

    diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
    index 30910e6c2346..41bc51c88002 100644
    --- a/drivers/iio/industrialio-buffer.c
    +++ b/drivers/iio/industrialio-buffer.c
    @@ -1600,6 +1600,11 @@ static int iio_buffer_enqueue_dmabuf(struct iio_buffer *buffer,
    if (dmabuf.flags & ~IIO_BUFFER_DMABUF_SUPPORTED_FLAGS)
    return -EINVAL;

    + /* Cyclic flag is only supported on output buffers */
    + if ((dmabuf.flags & IIO_BUFFER_DMABUF_CYCLIC) &&
    + buffer->direction != IIO_BUFFER_DIRECTION_OUT)
    + return -EINVAL;
    +
    return buffer->access->enqueue_dmabuf(buffer, &dmabuf);
    }

    diff --git a/include/uapi/linux/iio/buffer.h b/include/uapi/linux/iio/buffer.h
    index e4621b926262..2d541d038c02 100644
    --- a/include/uapi/linux/iio/buffer.h
    +++ b/include/uapi/linux/iio/buffer.h
    @@ -7,7 +7,8 @@

    #include <linux/types.h>

    -#define IIO_BUFFER_DMABUF_SUPPORTED_FLAGS 0x00000000
    +#define IIO_BUFFER_DMABUF_CYCLIC (1 << 0)
    +#define IIO_BUFFER_DMABUF_SUPPORTED_FLAGS 0x00000001

    /**
    * struct iio_dmabuf_alloc_req - Descriptor for allocating IIO DMABUFs
    --
    2.33.0
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