linux-kernel - Re: [PATCH v3 2/2] iio: adc: mcp3911: add support for the whole MCP39xx family

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Date:   Mon, 7 Aug 2023 18:53:21 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Marcus Folkesson <marcus.folkesson@...il.com>
Cc:     Kent Gustavsson <kent@...oris.se>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Cosmin Tanislav <demonsingur@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        ChiYuan Huang <cy_huang@...htek.com>,
        Haibo Chen <haibo.chen@....com>,
        Ramona Bolboaca <ramona.bolboaca@...log.com>,
        Ibrahim Tilki <Ibrahim.Tilki@...log.com>,
        ChiaEn Wu <chiaen_wu@...htek.com>,
        William Breathitt Gray <william.gray@...aro.org>,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] iio: adc: mcp3911: add support for the whole
 MCP39xx family

On Mon, Aug 07, 2023 at 09:18:31AM +0200, Marcus Folkesson wrote:
> Microchip does have many similar chips, add support for those.
> 
> The new supported chips are:
>   - microchip,mcp3910
>   - microchip,mcp3912
>   - microchip,mcp3913
>   - microchip,mcp3914
>   - microchip,mcp3918
>   - microchip,mcp3919

...

> +#define MCP3910_STATUSCOM_DRHIZ         BIT(20)

Is it deliberately using spaces? If so, why?

...

> +static int mcp3910_get_osr(struct mcp3911 *adc, int *val)
> +{
> +	int ret, osr;
> +
> +	ret = mcp3911_read(adc, MCP3910_REG_CONFIG0, val, 3);

> +	osr = FIELD_GET(MCP3910_CONFIG0_OSR, *val);
> +	*val = 32 << osr;
> +	return ret;

I believe this is wrong order. Or bad code. The rule of thumb is not pollute
the output variable if we know the error happened.

Same applies to another function.

> +}

...

> -	ret = mcp3911_config(adc);
> +	ret = device_property_read_u32(&adc->spi->dev, "microchip,device-addr", &adc->dev_addr);

Why not spi->dev? Ditto for other uses like this.

-- 
With Best Regards,
Andy Shevchenko