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

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Message-ID: <72df284b-66dd-2deb-13c2-cc0c9f4105cb@gmail.com>
Date:   Mon, 17 Jul 2023 14:23:26 +0200
From:   Andrea Collamati <andrea.collamati@...il.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        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 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).

Best regards

            Andrea