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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Wed, 23 May 2018 13:48:38 +0200
Message-ID: <CACRpkdYfjqRaUnYXhksXANbgyn++nUAda4D1prawGU1vZ06wQg@mail.gmail.com>
Subject: Re: [PATCH v7 3/3] gpio: pca953x: fix address calculation for pcal6524
To:     "H. Nikolaus Schaller" <hns@goldelico.com>
Cc:     Kumar Gala <galak@codeaurora.org>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Alexandre Courbot <gnurou@gmail.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Discussions about the Letux Kernel 
        <letux-kernel@openphoenux.org>, kernel@pyra-handheld.com
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On Thu, May 17, 2018 at 6:59 AM, H. Nikolaus Schaller <hns@goldelico.com> wrote:

> The register constants are so far defined in a way that they fit
> for the pcal9555a when shifted by the number of banks, i.e. are
> multiplied by 2 in the accessor function.
>
> Now, the pcal6524 has 3 banks which means the relative offset
> is multiplied by 4 for the standard registers.
>
> Simply applying the bit shift to the extended registers gives
> a wrong result, since the base offset is already included in
> the offset.
>
> Therefore, we have to add code to the 24 bit accessor functions
> that adjusts the register number for these exended registers.
>
> The formula finally used was developed and proposed by
> Andy Shevchenko <andy.shevchenko@gmail.com>.
>
> Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>

Patch applied.

Yours,
Linus Walleij