Re: [PATCH 0/2] Convert enum->pointer for data in the tmp51x match tables

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On Sun, Aug 20, 2023 at 05:36:02PM +0000, Biju Das wrote:
> Hi Guenter Roeck,
> 
> > Subject: RE: [PATCH 0/2] Convert enum->pointer for data in the tmp51x match
> > tables
> > 
> > Hi Guenter Roeck,
> > 
> > Thanks for the feedback.
> > 
> > > Subject: Re: [PATCH 0/2] Convert enum->pointer for data in the tmp51x
> > > match tables
> > >
> > > Either case, I would want to keep temp_config and the number of
> > > channels in struct tmp51x_data to avoid repeated double dereferences
> > > and because temp_config could change (resistance correction
> > > enabled/disabled should be a devicetree property, conversion rate as
> > > well as channel enable should be sysfs attributes, and channel
> > > enable/disable should also be devicetree properties). The value could
> > > also be used to support suspend/resume in the driver if someone wants to
> > add that at some point.
> > >
> > > In this context,
> > > 		if (data->id == tmp512 && channel == 4)
> > > 			return 0;
> > > is wrong because there are 3 or 4 channels, meaning the channel
> > > numbers are
> > > 0..3 and there is no channel 4. This should be "channel == 3"
> > > to disable the 4th channel on tmp512. Interesting that no one
> > > (including me ;-) noticed this.
> > 
> > If I am correct, as per above, only max number channels supported by the
> > chip can go to device data. That is the only HW difference between these 2
> > chips and other chip specific data can be derived from this.
> 
> I guess, the below initial values for temp_config
> is chip specific apart from the number of supported channels
> as we won't be able to derive from number of channels??
> 
> #define TMP512_TEMP_CONFIG_DEFAULT	0xBF80
> #define TMP513_TEMP_CONFIG_DEFAULT	0xFF80
> 
Bit 3-6 enable temperature sensors. The difference in bit 6
is that the 3rd external temperature sensor (which only exists for
tmp513) is enabled if the bit is set. So the base value for
TMP513_TEMP_CONFIG_DEFAULT would be 0xBF80 with bit 6 set if
the chip has four temperature sensors.

Guenter



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