Re: [PATCH 4/7] hwmon: (lm90) Add support for 2nd remote channel's offset register

[Guenter Roeck <linux@roeck-us.net>]

On 6/5/22 23:30, Slawomir Stepien wrote:
> On cze 05, 2022 11:03, Guenter Roeck wrote:
>> On Wed, May 25, 2022 at 09:36:54AM +0200, Slawomir Stepien wrote:
>>> From: Slawomir Stepien <slawomir.stepien@nokia.com>
>>>
>>> The ADT7461 supports offset register for both remote channels it has.
>>
>> ADT7481
> 
> Oops. I will fix that in new version.
> 
>>> Both registers have the same bit width (resolution).
>>>
>>> In the code, this device has LM90_HAVE_TEMP3 and LM90_HAVE_OFFSET flags,
>>> but the support of second remote channel's offset is missing. Add that
>>> implementation.
>>>
>>> Signed-off-by: Slawomir Stepien <slawomir.stepien@nokia.com>
>>> ---
>>>   drivers/hwmon/lm90.c | 37 ++++++++++++++++++++++++++++++++-----
>>>   1 file changed, 32 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
>>> index 02b211a4e571..d226f1dea2ba 100644
>>> --- a/drivers/hwmon/lm90.c
>>> +++ b/drivers/hwmon/lm90.c
>>> @@ -153,6 +153,8 @@ enum chips { adm1023, adm1032, adt7461, adt7461a, adt7481,
>>>   #define LM90_REG_REMOTE_TEMPL		0x10
>>>   #define LM90_REG_REMOTE_OFFSH		0x11
>>>   #define LM90_REG_REMOTE_OFFSL		0x12
>>> +#define LM90_REG_REMOTE2_OFFSH		0x34
>>> +#define LM90_REG_REMOTE2_OFFSL		0x35
>>
>> I don't think those are needed.
> 
> In lm90_temp_write() (unlike in lm90_update_limits()) the remote channel is *not* set. I find

... unless lm90_set_temp() is used to write the values. If I recall correctly
I didn't do that because selecting the remote channel seemed unnecessary.

> setting it (the remote channel) in lm90_temp_write() a waste of xfers, if we can address the
> registers directly. But if you prefer to have just one set of register and setting the remote
> channel bit, then sure I can do it like that.
> 
It isn't as if setting the offset happens all the time, so I'd prefer
to use lm90_set_temp() if that is possible.

Thanks,
Guenter