linux-kernel - Re: [PATCH v3 2/2] iio: dac: driver for MCP4821

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Message-ID: <20231220142638.7739c5d7@jic23-huawei>
Date: Wed, 20 Dec 2023 14:26:38 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Anshul Dalal <anshulusr@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
 devicetree@...r.kernel.org, Conor Dooley <conor+dt@...nel.org>, Lars-Peter
 Clausen <lars@...afoo.de>, Rob Herring <robh+dt@...nel.org>, Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 linux-kernel-mentees@...ts.linuxfoundation.org, Shuah Khan
 <skhan@...uxfoundation.org>
Subject: Re: [PATCH v3 2/2] iio: dac: driver for MCP4821

On Mon, 18 Dec 2023 22:17:34 +0530
Anshul Dalal <anshulusr@...il.com> wrote:

> Adds driver for the MCP48xx series of DACs.
> 
> Device uses a simplex SPI channel. To set the value of an output channel,
> a 16-bit data of following format must be written:
> 
> Bit field | Description
> 15 [MSB]  | Channel selection bit
>             0 -> Channel A
>             1 -> Channel B
> 13        | Output Gain Selection bit
>             0 -> 2x Gain (Vref = 4.096V)
>             1 -> 1x Gain (Vref = 2.048V)
> 12        | Output Shutdown Control bit
>             0 -> Shutdown the selected channel
>             1 -> Active mode operation
> 11-0 [LSB]| DAC Input Data bits
>             Value's big endian representation is taken as input for the
>             selected DAC channel. For devices with a resolution of less
>             than 12-bits, only the x most significant bits are considered
>             where x is the resolution of the device.
> Reference: Page#22 [MCP48x2 Datasheet]
> 
> Supported devices:
>   +---------+--------------+-------------+
>   | Device  |  Resolution  |   Channels  |
>   |---------|--------------|-------------|
>   | MCP4801 |     8-bit    |      1      |
>   | MCP4802 |     8-bit    |      2      |
>   | MCP4811 |    10-bit    |      1      |
>   | MCP4812 |    10-bit    |      2      |
>   | MCP4821 |    12-bit    |      1      |
>   | MCP4822 |    12-bit    |      2      |
>   +---------+--------------+-------------+
> 
> Devices tested:
>   MCP4821 [12-bit single channel]
>   MCP4802 [8-bit dual channel]
> 
> Tested on Raspberry Pi Zero 2W
> 
> Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/22244B.pdf #MCP48x1
> Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/20002249B.pdf #MCP48x2
> Signed-off-by: Anshul Dalal <anshulusr@...il.com>
> 
> ---
> 
> Changes for v3:
> - no updates
>
Oops. I reviewed v2.  Please find comments there.

Jonathan