linux-kernel - Re: [PATCH v3 2/2] thermal: uniphier: add UniPhier thermal driver

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Message-ID: <CAK7LNASfco5oj8pLDykqq_xFsx4P0qjR1CuXsbF0n-1v0PBGKg@mail.gmail.com>
Date:   Wed, 5 Jul 2017 21:20:16 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Cc:     rui.zhang@...el.com, Eduardo Valentin <edubezval@...il.com>,
        linux-pm@...r.kernel.org,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Masami Hiramatsu <masami.hiramatsu@...aro.org>,
        Jassi Brar <jaswinder.singh@...aro.org>
Subject: Re: [PATCH v3 2/2] thermal: uniphier: add UniPhier thermal driver

2017-07-05 20:50 GMT+09:00 Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>:

> +
> +#define TMOD                           0x0928
> +#define TMOD_MASK                      GENMASK(9, 0)
> +
 [ snip ]
> +
> +       /*
> +        * The bit[8:0] of TMOD register represents 2's complement value
> +        * of temperature in Celsius. Since bit8 of TMOD shows a sign bit,
> +        * 32bit temperature value is obtained by sign extension.
> +        */


Apparently, this comment does not match your code:

     #define TMOD_MASK                      GENMASK(9, 0)


TMOD_MASK is indicating bit[9:0].



Digging into the patch history, now I understood what happened.



In v1, you described
#define TMOD_MASK         0x1ff

This was correct.


In v2, you converted it into
#define TMOD_MASK          GENMASK(9, 0)

This was misconversion.  It should be GENMASK(8, 0)



Anyway, TMOD_MASK is not used any more.


> +       *out_temp = sign_extend32(temp, 8) * 1000;


Why magic number here?

   /* MSB of the TMOD field is a sign bit */
   *out_temp = sign_extend32(temp, TMOD_WIDTH) * 1000;


-- 
Best Regards
Masahiro Yamada