typo in sync_for_cpu sample in documentation?

[5p00kk]

Hi,

In Readme.md in section https://github.com/ikwzm/udmabuf#sync_for_cpu it states that:

If '1' is written to device file, if sync_direction is 2(=DMA_FROM_DEVICE) or 0(=DMA_BIDIRECTIONAL), the write to the device file invalidates a cache specified by sync_offset and sync_size.

but in both sync_for_cpu code samples

unsigned long sync_for_cpu = 1;

I expect this is just a typo in the code sample right?

[KAWAZOME Ichiro]

No, it's not a typo.
Whenever you run sync_for_cpu, you must write a non-zero value.
Therefore, 1 is set in sync_for_cpu to make the least significant bit 1.

[5p00kk]

Sorry I actually copied wrong line, I meant:

unsigned int sync_direction = 1;

I'd expect direction to be either 2 or 0 based on the description.

[KAWAZOME Ichiro]

As you pointed out, it is confusing as a sample code, so I corrected it.

Thank you for issue.