linux-kernel - Re: [PATCH 1/4] power: supply: max17042

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Message-ID: <f15c415a-ad08-ae4f-c79c-574964ab9cb0@kernel.org>
Date:   Fri, 18 Mar 2022 10:06:42 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Hans de Goede <hdegoede@...hat.com>,
        Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Sebastian Reichel <sre@...nel.org>, linux-pm@...r.kernel.org
Cc:     Purism Kernel Team <kernel@...i.sm>, Rob Herring <robh@...nel.org>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 1/4] power: supply: max17042_battery: Add unit conversion
 macros

On 18/03/2022 10:00, Hans de Goede wrote:
> Hi,
> 
> On 3/18/22 09:16, Krzysztof Kozlowski wrote:
>> On 18/03/2022 01:10, Sebastian Krzyszkowiak wrote:
>>> Instead of sprinkling the code with magic numbers, put the unit
>>> definitions used by the gauge into a set of macros. Macros are
>>> used instead of simple defines in order to not require floating
>>> point operations for divisions.
>>>
>>> Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@...i.sm>
>>> ---
>>>  drivers/power/supply/max17042_battery.c | 40 +++++++++++++++----------
>>>  1 file changed, 24 insertions(+), 16 deletions(-)
>>>
>>> diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c
>>> index ab031bbfbe78..c019d6c52363 100644
>>> --- a/drivers/power/supply/max17042_battery.c
>>> +++ b/drivers/power/supply/max17042_battery.c
>>> @@ -51,6 +51,15 @@
>>>  
>>>  #define MAX17042_VMAX_TOLERANCE		50 /* 50 mV */
>>>  
>>> +#define MAX17042_CURRENT_LSB		1562500ll /* µV */
>>
>> Is this really long long? The usage in max17042_get_status() is with int
>> operand and result.
> 
> The "ll" is part of the original code which these macros replace,
> dropping the "ll" is IMHO out of scope for this patch, it would
> clearly break the only change 1 thing per patch/commit rule.

Not in max17042_get_status(). The usage there is without ll. Three other
places use it in 64-bit context (result is 64-bit), so there indeed. But
in max17042_get_status() this is now different.


Best regards,
Krzysztof