linux-kernel - Re: [PATCH v2] hwmon (max6639): Use regmap

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Date: Thu, 2 May 2024 11:22:40 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Naresh Solanki <naresh.solanki@...ements.com>
Cc: Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] hwmon (max6639): Use regmap

On 5/2/24 10:25, Naresh Solanki wrote:
[ ... ]

>>> +     u8 pwm[MAX6639_NDEV];           /* Register value: Duty cycle 0..120 */
>>
>> pwm caching needs to be dropped as well. It is no longer initialized in
>> max6639_init_client(), but updated and later used in pwm_store() and
>> pwm_show(). Looking at the datasheet, the pwm registers are volatile
>> and should not be cached in the first place.
> Yes. I did that but found that the register is write only. i.e.,

Odd. The datasheet says that it is r/w or, rather, that reading it returns
the _current_ pwm value and writing it sets the target pwm value in pwm mode.

What happens when the register is read ?

Thanks,
Guenter