[lm-sensors] [patch lm-sensors 2.10.4] i2cdetect mislabels PEC

David Brownell david-b at pacbell.net
Wed Sep 19 23:55:37 CEST 2007


On Wednesday 19 September 2007, Jean Delvare wrote:
> Hi David,
> 
> On Tue, 18 Sep 2007 15:45:36 -0700, David Brownell wrote:
> > > > -	  .name = "SMBus PEC" },
> > > > +	  .name = "SMBus PEC in Hardware" },
> > >
> > > I agree that the current situation is confusing, I had noticed this
> > > already when reworking the PEC support in 2.6.15, but postponed fixing
> > > it.
> > >
> > > However, I don't think that what you proposed is the proper fix. We
> > > don't care whether PEC is implemented in hardware or software. What
> > > really matters is whether it is implemented at all, or not. So I'd
> > > rather rename I2C_FUNC_SMBUS_HWPEC_CALC to I2C_FUNC_SMBUS_PEC, and have
> > > i2c-algo-bit and other drivers declare that they support it. What do
> > > you think?
> > 
> > How about just not exposing that capability from i2cdetect at all?
> > 
> > There's a software implementation that's always available.  Whether
> > that's used, or a (presumably accelerated) hardware one is used is
> > purely an implementation issue, not an interface issue that a driver
> > would have any reason to care about.
> 
> This is not true. Software PEC support is only available for adapters
> emulating SMBus support using I2C-level messaging (e.g. i2c-algo-bit.)

OK.  I never use non-emulated SMBus, so it's hard to remember
about that other option.


> For non-I2C SMBus masters, PEC support is there only if the hardware
> explicitly supports it, it cannot be emulated. For example the Intel
> ICH3 can't do PEC. That's the reason why having a functionality bit for
> SMBus PEC makes sense.

Right ... then your suggestion above would seem to be The Answer,
although rather than modify algo-bit etc I'd just add that flag
into I2C_FUNC_SMBUS_EMUL.  Maybe that's what you meant.

The "rename" would presumably involve leaving the old symbol around
for a while, deprecated so gcc warns when it's used.

- Dave




More information about the lm-sensors mailing list