linux-kernel - Re: [PATCH v9 2/7] i2c: Add FSI-attached I2C master algorithm

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Date:   Tue, 5 Jun 2018 12:17:48 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:     Eddie James <eajames@...ux.vnet.ibm.com>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Rob Herring <robh+dt@...nel.org>,
        Joel Stanley <joel@....id.au>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v9 2/7] i2c: Add FSI-attached I2C master algorithm

On Tue, Jun 5, 2018 at 2:38 AM, Benjamin Herrenschmidt
<benh@...nel.crashing.org> wrote:
> On Mon, 2018-06-04 at 22:21 +0300, Andy Shevchenko wrote:
>> > +#define I2C_INT_ENABLE         0x0000ff80
>> > +#define I2C_INT_ERR            0x0000fcc0
>>
>> Now it looks like a flags combinations.
>> For me as for reader would be better to see quickly a decoded line.
>>
>> My proposal is to introduce something like following
>>
>> _INT_ALL  GENMASK()
>> _INT_ENABLE (_INT_ALL & ~(_FOO | _BAR))
>> _INT_ERR ... similar way as above ...
>>
>> What do you think?
>
> I don't think this absolutely needs to change but yes, open coding is
> error prone. However I would think it more readable to use positive
> logic and just list all the bits that are *set* even if it's a bit more
> text:
>
> #define I2C_INT_ERR     (I2C_INT_INV_CMD        |\
>  I2C_INT_PARITY         |\
>                          I2C_INT_BE_OVERRUN     |\
>                         .../...)
>
> #define I2C_INT_ENABLE  (I2C_INT_ERR            |\
>                          I2C_INT_DAT_REQ        |\
>                          I2C_INT_CMD_COMP)

Yep, it's fine.
I prefered though slightly different style (not putting first value on
the same line with #define), but it doesn't matter.

>
> Note: Eddie, I notice I2C_INT_BUSY is in "ERR" but not in "ENABLE", any
> reason for that ?

Exactly the reason why I payid attention on these values.

-- 
With Best Regards,
Andy Shevchenko