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4538c18568
The dmaengine buffer has some length alignment requirements that can differ from platform to platform. If the length alignment requirements are not met unexpected behavior like dropping of samples can occur. Currently these requirements are not reported and applications need to know the requirements of the platform by some out-of-band means. Add a new buffer attribute that reports the length alignment requirements called `length_align_bytes`. The reported length alignment is in bytes that means the buffer length alignment in sample sets depends on the number of enabled channels and the bytes per channel. Applications using this attribute to determine the buffer size requirements need to consider this. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
20 lines
857 B
Plaintext
20 lines
857 B
Plaintext
What: /sys/bus/iio/devices/iio:deviceX/buffer/length_align_bytes
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KernelVersion: 5.4
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Contact: linux-iio@vger.kernel.org
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Description:
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DMA buffers tend to have a alignment requirement for the
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buffers. If this alignment requirement is not met samples might
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be dropped from the buffer.
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This property reports the alignment requirements in bytes.
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This means that the buffer size in bytes needs to be a integer
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multiple of the number reported by this file.
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The alignment requirements in number of sample sets will depend
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on the enabled channels and the bytes per channel. This means
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that the alignment requirement in samples sets might change
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depending on which and how many channels are enabled. Whereas
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the alignment requirement reported in bytes by this property
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will remain static and does not depend on which channels are
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enabled.
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