Re: [PATCH i2c-tools] i2ctransfer: add support for I2C_M_RECV_LEN

Wolfram Sang
2020-08-02T21:38:31Z

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Hi Daniel,

> > + __u16 len = recv_len ? msgs[i].buf[0] + 1 : msgs[i].len;
>
> This is post-ioctl()? (Sorry, still not familiar enough with i2c-tools.)

Yes, read buffers are only printed after the ioctl. And 'print_msgs' is
probably the most complex function within this tool :/

> It isn’t wrong, but shouldn’t be necessary.
> Unless the adapter driver you’re using went astray. Not ruling that out.

I have just checked existing I2C_M_RECV_LEN handling. Quite some drivers
do it wrong. And there is no consistency in what they return. Lots of
things to fix there...

Thanks for the quick comments,

Wolfram