linux-kernel - Re: [PATCH v2 0/2] add mcp4728 I2C DAC driver

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Message-ID: <55177316-c3f9-5566-e2d2-202913fca8f2@linaro.org>
Date:   Mon, 17 Jul 2023 17:03:45 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Andrea Collamati <andrea.collamati@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     Krzysztof Kozlowski <krzk@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        William Breathitt Gray <william.gray@...aro.org>,
        Angelo Dureghello <angelo.dureghello@...esys.com>,
        Fabio Estevam <festevam@...il.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/2] add mcp4728 I2C DAC driver

On 17/07/2023 14:23, Andrea Collamati wrote:
> On 7/17/23 09:17, Krzysztof Kozlowski wrote:
>>>> Shouldn't this binding be just merged with existing mcp4725? Are you
>>>> sure it's not similar device, IOW, are you sure you do not have vref supply?
>>>>
>>> Unfortunately they are not that similar. MCP4728 has two vref choices:
>>>
>>> - Use Vdd (power supply) as Vref
>>>
>>> - User Internal 2.048 V Vref source.
>> Exactly the same as existing mcp4726, so what is the problem?
> 
> MCP4726 has 2 separate pins, VDD and VREF that can be both used as external Vref depending on configuration.
> 
> MCP4728 has only one external vref pin, VDD pin. The other vref source is internal and fixed to 2.048V.
> 
> Furthermore MCP4728  has four independent channels. For each channels it's possible to choose whether
> 
> using VDD (External VRef) or 2.048V (Internal Vref).

Indeed, so new binding makes sense.

Best regards,
Krzysztof