Hi George et al,
Its great to see the aSC7621 driver being resurrected, but I notice in
the patches flying about recently (see LKML 22 Feb 2010 in particular)
that the voltage calculation is a bit off, as I already pointed out in a
previous review. To get the correct results, it is much easier to use
the 3/4 scale values given in the data sheet, and also be careful to do
the multiplication before the division to avoid loss of precision (Hint:
The BSD version of the driver does it correctly!).
See below:
static int asc7621_in_scaling[] = {
2500, 2250, 3300, 5000, 12000
};
For the 10-bit voltage registers, do something like this:
long regval =
(data->reg[param->msb[0]] << 8) |
(data->reg[param->lsb[0]]);
regval = (regval >> 6) * asc7621_in_scaling[index] / (192 << 2);
And for the 8-bit registers:
long regval = data->reg[param->msb[0]];
regval = regval * asc7621_in_scaling[index] / 192;
I've not yet checked the code thoroughly to look for any of the other
fixes which were put in during our previous discussions, but I suspect
that some of the other minor fixes which were discussed on the mailing
list may have been left out.
This was a very ambitious driver in that it included all the fancy
thermal management features of the aSC7621, and a complete review and
testing of everything in the driver was a lot more than I had the
stomach for. I'm glad to see others have now picked it up though!
Best wishes,
Ken.
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