Re: Sensor with 7 bit address above 0x77

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

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> Both programs mention the limitations in their manpages but give *no explanation* on why they
> exist or where those special values came from.

That could be added to them. But the first thing to look for such
information is still the I2C specification which has a section about
reserved addresses.

> The comment above the line states that addresses 0x78-0x7b are used for 10-bit slave
> addressing. The documentation on 10-bit slave addressing (Documentation/i2c/ten-bit-addresses)
> says "...The leading 0xa (= 10) represents the 10 bit mode...". Wouldn't such an address
> on the bus be quite problematic as 0xA has a leading 1 bit (read/write select?).

Please read the above specification to understand how 10 bit addresses
are transferred over the wire. I think reading it will answer most of
your questions.

> Is there a specific reason I can override i2cdetect but not i2cdump?

Probably not. More likely, nobody needed it until now. Which is
understandable since the device you have has to be considered broken
regarding the I2C standard. But I think patches adding that could be
acceptable. Jean has the last word on this.


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