linux-kernel - Re: [PATCH v2 2/2] power: supply: add CellWise cw2015 fuel gauge driver

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Date:   Tue, 10 Mar 2020 19:55:42 +0100
From:   Tobias Schramm <t.schramm@...jaro.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Tobias Schramm <t.schramm@...jaro.org>
Cc:     Sebastian Reichel <sre@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] power: supply: add CellWise cw2015 fuel gauge
 driver

Hi Andy,

thanks for your review. Please find my comments inline.

>> +#define CW2015_DEFAULT_MONITOR_MS		8000
> 
> 8 seconds? Any comments about this?
>
Default suggested by CellWise Android example code. I'll add a comment
explaining that.

>> +static int cw_read(struct cw_battery *cw_bat, u8 reg, u8 *val)
>> +{
>> +	u32 tmp;
>> +	int ret;
>> +
>> +	ret = regmap_read(cw_bat->regmap, reg, &tmp);
>> +	*val = tmp;
>> +	return ret;
>> +}
>> +
[ ... ]
>
> This two has no value. Why?
>
This helper translates the memory write size. An u8 * is passed in while
regmap_read takes an unsigned int *. I'll drop it and just use an
unsigned int in the first place though.

>> +static int cw_read_word(struct cw_battery *cw_bat, u8 reg, u16 *val)
>> +{
>> +	u8 reg_val[2];
>> +	int ret;
>> +
>> +	ret = regmap_raw_read(cw_bat->regmap, reg, reg_val, 2);
>> +	*val = (reg_val[0] << 8) + reg_val[1];
>> +	return ret;
>> +}
> 
> NIH BE type of readings? Can REGMAP_ENDIAN_BIG help?

Not really, or can it? Registers on the cw2015 are a wild mix of single
bytes and words. There does not seem to be a per register override for
reg_/val_bits.

> 
> I didn't review some parts because of style issues. Please, fix all of them and
> send v2.
> 
I'll fix all style issues I find.

>> +	cancel_delayed_work(&cw_bat->battery_delay_work);
> 
> Are you sure you have no scheduled work after that?
> 

Will replace that with cancel_delayed_work_sync.


Best Regards,

Tobias