Re: [lm-sensors] [PATCH] hwmon: (w83627ehf) Fix number of fans for NCT6776F

[Guenter Roeck <guenter.roeck@ericsson.com>]

On Sat, Jan 28, 2012 at 03:34:00PM -0500, Jean Delvare wrote:
> On Sat, 28 Jan 2012 09:04:28 -0800, Guenter Roeck wrote:
> > Logic was that I only need to check if the fans are connected to 90..92 if they are
> > not connected to 3..5. However, it looks like 90..92 take precedence, so
> > I think I have to check if the fans are connected to 90..92 first, and only
> > check if they are connected to 3..5 if they are not connected to 90..92.
> > 
> > Something like:
> > 
> > 	fan3pin = 0;
> > 	fan4pin = 0;
> > 	fan5pin = 0;
> > 	if (superio_inb(sio_data->sioreg, 0x27) & 0x80) {
> >                 superio_select(sio_data->sioreg, W83627EHF_LD_HWM);
> >                 regval = superio_inb(sio_data->sioreg, SIO_REG_ENABLE);
> >                 fan3pin = !!(regval & 0x80);
> >                 fan4pin = !!(regval & 0x40);
> >                 fan5pin = !!(regval & 0x20);
> >         }
> > 	if (!fan3pin)
> > 		fan3pin = !(superio_inb(sio_data->sioreg, 0x24) & 0x40);
> > 	if (!fan4pin)
> > 		fan4pin = !!(superio_inb(sio_data->sioreg, 0x1C) & 0x01);
> > 	if (!fan5pin)
> >   		fan5pin = !!(superio_inb(sio_data->sioreg, 0x1C) & 0x02);
> > 
> > Does that make sense ?
> 
> Yes, this should work in practice. However some improper chip
> configurations would not be dealt with properly by the code above. For
> example bits 5, 6 and 7 of configuration register SIO_REG_ENABLE set but
> bit 7 of configuration register 0x27 not set makes no sense, but if the
> chip is so configured then I believe the fans cannot be monitored,
> regardless of the bit values in configuration registers 0x24 and 0x1C.
> If you want to handle this case, you have to check every fan
> separately, like:
> 
> 	gpok = superio_inb(sio_data->sioreg, 0x27) & 0x80;
> 	regval = superio_inb(sio_data->sioreg, SIO_REG_ENABLE);
> 
> 	if (regval & 0x80)
> 		fan3pin = gpok;
> 	else
> 		fan3pin = !(superio_inb(sio_data->sioreg, 0x24) & 0x40);
> 
> 	if (regval & 0x40)
> 		fan4pin = gpok;
> 	else
> 		fan4pin = !!(superio_inb(sio_data->sioreg, 0x1C) & 0x01);
> 	[etc]
> 
> It's up to you if you want to do that for absolute correctness
> (assuming I read the datasheet properly...) or prefer to stick to your
> approach which should be equivalent for properly configured chips.
> 
I might as well (try to) do it right, so I'll use your approach.
I'll send an updated patch in a minute.

Guenter 

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