Re: i2c and indirect vs. direct config

[Paul Goyette <paul%whooppee.com@localhost>]

On Sat, 2 Jun 2018, Jason Thorpe wrote:

> > On Jun 1, 2018, at 3:45 PM, Paul Goyette <paul%whooppee.com@localhost> wrote:
> >
> > There is at least one i2c bus controller that explicitly doesn't
> > handle "quick" transactions - the imc controller built into the Intel
> > X99 chip-set.  The docs are pretty clear that it implements an
> > absolute minimum subset of i2c, just barely enough to talk to the SPD
> > ROMs on memory DIMMs.
>
> Wait, are you sure about that?  The X99 data sheet explicitly says is 
> supports the SMBus “quick” command.

Hmmm, I must have mis-read or mis-understood something.

In any case, the current driver code doesn't seem to support "quick".

From src/sys/arch/x86/pci/imcsmb/imcsmb.c in routine imcsmb_exec() we 
have:

        if ((cmdlen != 1) || (len > 2) || (len < 1))
                return EINVAL;

(If I remember correctly, the quick command has cmdlen == 0 which would 
fail the first part of this test.)


For changing this, I'd have to defer to msaitoh@ (the author of the 
driver).




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