Date: Fri, 28 Nov 2008 21:39:25 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: des@des.no Cc: raj@semihalf.com, nwhitehorn@freebsd.org, freebsd-arch@freebsd.org Subject: Re: Enumerable I2C busses Message-ID: <20081128.213925.-1597343424.imp@bsdimp.com> In-Reply-To: <86od054iaz.fsf@ds4.des.no> References: <86myfq9uha.fsf@ds4.des.no> <C1917DFE-AA7F-4042-8A8F-088599FCDBB4@semihalf.com> <86od054iaz.fsf@ds4.des.no>
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In message: <86od054iaz.fsf@ds4.des.no>
Dag-Erling_Smørgrav <des@des.no> writes:
: Rafał Jaworowski <raj@semihalf.com> writes:
: > Well, hard-coded addresses and conflicting assignments between vendors
: > do not technically prevent from scanning the bus; actually, our
: > current iicbus code can do bus scaning when compiled with a diag
: > define.
:
: I haven't looked at how that is implemented, but - I2C version 3
: describes device enumeration and identification, but AFAIK very few
: devices actually support it.
:
: This is really stupid, BTW. Philips could easily have required the
: first few bytes of the device address space to contain a vendor / device
: ID, along the lines of PCI and USB, from the start. I wonder: did it
: not occur to them, or did they intentionally leave it out to save a few
: microcents per chip?
EEPROMs typically don't have registers at all. They are just memory.
Forcing them to have set content would break all kinds of
applications.
Warner
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