linux-kernel - Re: [PATCH v2] eeprom: at25: Add DT support for EEPROMs with odd address bits

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Message-ID: <20171212205439.ijhvzmsumiu3l5pp@rob-hp-laptop>
Date:   Tue, 12 Dec 2017 14:54:39 -0600
From:   Rob Herring <robh@...nel.org>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Mark Rutland <mark.rutland@....com>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ivo Sieben <meltedpianoman@...il.com>,
        Wolfram Sang <wsa@...-dreams.de>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] eeprom: at25: Add DT support for EEPROMs with odd
 address bits

On Fri, Dec 08, 2017 at 02:46:41PM +0100, Geert Uytterhoeven wrote:
> Certain EEPROMS have a size that is larger than the number of address
> bytes would allow, and store the MSB of the address in bit 3 of the
> instruction byte.
> 
> This can be described in platform data using EE_INSTR_BIT3_IS_ADDR, or
> in DT using the obsolete legacy "at25,addr-mode" property.
> But currently there exists no non-deprecated way to describe this in DT.
> 
> Hence extend the existing "address-width" DT property to allow
> specifying 9 address bits, and enable support for that in the driver.
> 
> This has been tested with a Microchip 25LC040A.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> v2:
>   - Do not consider odd address widths of 17 or 25 bits,
>   - Move handling inside the switch() statement.
> ---
>  Documentation/devicetree/bindings/eeprom/at25.txt | 4 +++-
>  drivers/misc/eeprom/at25.c                        | 3 +++
>  2 files changed, 6 insertions(+), 1 deletion(-)

Reviewed-by: Rob Herring <robh@...nel.org>