Display Data Channel Command Interface (DDC/CI) ioctls [PSARC/2007/695 FastTrack timeout 01/02/2008]

[Garrett D'Amore]

Eric Sultan wrote:
> Garrett D'Amore wrote:
>> ...
>> How will a client know which port is which?  Are these exclusively 
>> for control interfaces, or is here an intent to be able to use these 
>> ioctls to access EDID data?
>>
>>    -- Garrett
> The client, or his installation, connected the monitors and so knows 
> which is which.
> Even so, he can fetch EDID info from the two ports and learn what's 
> connected.
>
> By convention, the ports are labeled "1" and "2".
>
> These ioctls are exclusively for DDC/CI.  The same struct would work 
> for EDID,
> but one would need to use the EDID i2c address instead of the DDC/CI 
> i2c address.
> The format of the payload in the buffer is different for EDID and for 
> DDC/CI.
>
> Currently, in SPARC graphics at least, each device has its own ioctls 
> for fetching EDID.
> I'd prefer to define a generalized set for EDID, but that's beyond the 
> scope of this proposal.

Understood, thanks for the clarification.  I've never used DDC/CI, and 
didn't realize that there was a separate i2c address, but now that I 
think about it it makes perfect sense. ;-)

    -- Garrett