Re: [RFC PATCH] i2c: gpio: fault-injector: add 'lose_arbitration' injector

[Wolfram Sang <wsa@the-dreams.de>]

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Hi Geert,

> > Sure thing, this was a typical RFC marker :) It is now calculated based
> > on bit_data.udelay and has a comment.
> 
> But that value bears no direct relation to the transfer speed as used by the
> master to interfere with, right?

Yeah, the assumption would have been that i2c-gpio is configured as the
same speed as the master under test. However, ...

> Still, you have to guess anyway.

... I changed the user API meanwhile. The value you write is the value
used for this delay. Because 'number of interfered arbitrations' is
vague anyhow. Because of latencies, interrupts sometimes trigger twice
per interference, so this number becomes meaningless.

> > Any pointer for that information? I seem to recall that the format
> > string is also used to parse the user string to the set function. I
> > sadly can't find that documented, but all the helper macros in
> > fs/debugfs/file.c have a format string, too, even if WO.
> 
> fs/libfs.c:struct simple_attr {
> 
>         const char *fmt;        /* format for read operation */
> 
> It's being parsed using simple_strtoll(), so it takes whatever format is being
> passed by the writer.
> 
> Perhaps you were confused by the term "read", which is from the point of
> view of userspace, not of the driver.

Because all other users (even WO) have that still set, I prefer
consistency here.

Will send out next version, including panic-fault-injector, hopefully
today.

Thanks,

   Wolfram

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