Re: [PATCH i2c-tools v3 0/2] Add support for message modifier flags

[Jean Delvare <jdelvare@suse.de>]

Hi Benoît,

On Tue, 27 Jan 2026 10:25:56 +0100, Benoît Monin wrote:
> I2C messages can be modified with a set of flags covered by the protocol
> mangling and the skip repeated start functionalities. This series add
> support for such flags to i2cdetect and i2ctransfer.
> 
> The first patch shows the support of protocol mangling and repeated
> start skipping in the output of 'i2cdetect -F'.
> 
> The second patch adds the parsing of optional flags to i2ctransfer
> message description. Those command-line flags then set the i2c message
> flags alongside the read/write flag.
> 
> I wrote these changes to test the insertion of I2C_M_STOP flag in
> multi-message transactions with i2ctransfer, but the other flags may be
> useful for various test scenarios. 
> 
> Signed-off-by: Benoît Monin <benoit.monin@bootlin.com>
> ---
> Changes in v3:
> - Use ifdefs to check that the flags and functionalities are known
>   at compile-time.
> - Check that the adapter supports the requested flags before using them
>   in i2ctransfer.
> - Add a warning in i2ctransfer man page about the risk of using these
>   flags.
> - Link to v2: https://lore.kernel.org/r/20251223-msg-flags-v2-0-8d934a4366e2@bootlin.com
> 
> Changes in v2:
> - Document the flags in i2ctransfer.8 man page.
> - Link to v1: https://lore.kernel.org/r/20251128-msg-flags-v1-0-6353f26fa6bc@bootlin.com
> 
> ---
> Benoît Monin (2):
>       i2cdetect: Display mangling and nostart support
>       i2ctransfer: Add optional message modifier flags
> 
>  tools/i2cdetect.c   |   8 ++++
>  tools/i2ctransfer.8 |  28 ++++++++++++-
>  tools/i2ctransfer.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++------
>  3 files changed, 141 insertions(+), 14 deletions(-)

Both patches look very good to me. I was able to test the i2cdetect
patch and did not find any issue. I can't easily test the i2ctransfer
patch though.

Wolfram, can you please give some basic testing to the i2ctransfer
patch? Not necessarily with the mangling flags, but at least test that
the changes do not introduce any regression for your own use cases?

Thanks,
-- 
Jean Delvare
SUSE L3 Support