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cbb4451404
10-bit addresses overlap with traditional 7-bit addresses, leading in device name collisions. Add an arbitrary offset to 10-bit addresses to prevent this collision. The offset was chosen so that the address is still easily recognizable. Signed-off-by: Jean Delvare <khali@linux-fr.org> Acked-by: Wolfram Sang <w.sang@pengutronix.de>
24 lines
1.2 KiB
Text
24 lines
1.2 KiB
Text
The I2C protocol knows about two kinds of device addresses: normal 7 bit
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addresses, and an extended set of 10 bit addresses. The sets of addresses
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do not intersect: the 7 bit address 0x10 is not the same as the 10 bit
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address 0x10 (though a single device could respond to both of them).
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I2C messages to and from 10-bit address devices have a different format.
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See the I2C specification for the details.
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The current 10 bit address support is minimal. It should work, however
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you can expect some problems along the way:
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* Not all bus drivers support 10-bit addresses. Some don't because the
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hardware doesn't support them (SMBus doesn't require 10-bit address
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support for example), some don't because nobody bothered adding the
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code (or it's there but not working properly.) Software implementation
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(i2c-algo-bit) is known to work.
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* Some optional features do not support 10-bit addresses. This is the
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case of automatic detection and instantiation of devices by their,
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drivers, for example.
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* Many user-space packages (for example i2c-tools) lack support for
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10-bit addresses.
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Note that 10-bit address devices are still pretty rare, so the limitations
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listed above could stay for a long time, maybe even forever if nobody
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needs them to be fixed.
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