linux-kernel - Re: [PATCH] eeprom: at24: correctly set the size for at24mac402

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Date:   Tue, 28 Nov 2017 12:25:12 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Claudiu Beznea <Claudiu.Beznea@...rochip.com>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH] eeprom: at24: correctly set the size for at24mac402

On Mon, Nov 27, 2017 at 11:06 PM, Bartosz Golaszewski <brgl@...ev.pl> wrote:
> There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down
> the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6,
> making it impossible to read it all.
>
> Fix it by manually adjusting the value in probe().
>
> This patch contains a temporary fix that is suitable for stable
> branches. Eventually we'll probably remove the call to ilog2() while
> converting the magic values to actual structs.

> +       /*
> +        * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while
> +        * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4.
> +        *
> +        * Eventually we'll get rid of the magic values altoghether in favor of
> +        * real structs, but for now just manually set the right size.
> +        */
> +       if (chip.flags & AT24_FLAG_MAC && chip.byte_len == 4)

I didn't check, but do we need to test for len == 4 at all?

> +               chip.byte_len = 6;

-- 
With Best Regards,
Andy Shevchenko