[U-Boot] I2C: OMAP: spurious i2c probe addresses

Heiko Schocher
2011-05-26T07:14:17Z

Hello Michael,

Michael Jones wrote:
> On 05/25/2011 05:38 PM, Michael Jones wrote:
>> While running v2011.06-rc1, I noticed some new behavior on my OMAP3 i2c
>> bus. I tracked it to commit 0e57968a215d1b, "I2C: OMAP: detect more
>> devices when probing an i2c bus". It detects more devices indeed, such
>> as some that don't even exist. Even better than that, it detects
>> different devices every time. It looks like just false positives, the
>> existent devices seem to always be found among the ghost devices.
>>
>> Here's the behavior I see:
>> --------------------------
>> # i2c probe
>> Valid chip addresses: 05 18 30 49 50 51 5E 7A
>> # i2c probe
>> Valid chip addresses: 02 06 0B 18 1D 24 25 30 35 50 51 57 5D 6F 7C
>> # i2c probe
>> Valid chip addresses: 18 2E 30 33 35 50 51 62 6F
>> # i2c probe
>> Valid chip addresses: 18 1B 1F 2D 30 46 50 51 5C 5D
>> # i2c probe
>> Valid chip addresses: 0A 18 21 26 2B 30 32 50 51 60 66 69 6D 79
>> # i2c probe
>> Valid chip addresses: 08 09 18 1B 30 50 51 5E 6C
>>
>>
>> Here's what it looks like after reverting the commit:
>> ------------------------------------------
>> # i2c probe
>> Valid chip addresses: 18 30 50 51
>> # i2c probe
>> Valid chip addresses: 18 30 50 51
>> # i2c probe
>> Valid chip addresses: 18 30 50 51
>> # i2c probe
>> Valid chip addresses: 18 30 50 51
>>
>>
>> -Michael
>
> Sorry- relevant point here: I have a device with a 2-byte subaddress,
> which I suspect is the culprit here. As Nick mentioned in his commit
> message, such devices are unsupported by the current OMAP i2c driver.
> I'm in the process of adding support for 2-byte subaddresses to the
> driver. In light of the above, I now realize that such changes will
> probably have to involve i2c_probe() as well.

Ah, good point. Thanks! (I just looked at this commit, and couldn;t
find, why it does such a mess) ... waiting for a patch, which adds
2-byte subaddress support ;-)

bye,
Heiko
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