Re: [PATCH v5 10/10] iio: dac: add support for Microchip MCP48FEB02

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Missing POR (Power-On Reset) delay after enabling the VDD regulator in probe.
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commit 3cf6710da958614daaff4a4a7e99d396c3398a95
Author: Ariana Lazar <ariana.lazar@microchip.com>

iio: dac: add support for Microchip MCP48FEB02

This commit introduces SPI support for the Microchip MCP48FEB02 series DACs.
It adds a new SPI driver file and the corresponding Kconfig and Makefile
changes.

> diff --git a/drivers/iio/dac/mcp47feb02-spi.c b/drivers/iio/dac/mcp47feb02-spi.c
> new file mode 100644
> index 0000000000000..0c68d7c318cb2
> --- /dev/null
> +++ b/drivers/iio/dac/mcp47feb02-spi.c

[ ... ]

> +static int mcp47feb02_spi_probe(struct spi_device *spi)
> +{
> +	const struct mcp47feb02_features *chip_features;
> +	struct device *dev = &spi->dev;
> +	struct regmap *regmap;

[ ... ]

> +	if (IS_ERR(regmap))
> +		return dev_err_probe(dev, PTR_ERR(regmap), "Error initializing SPI regmap\n");
> +
> +	return mcp47feb02_common_probe(chip_features, regmap);
> +}

[Severity: High]
This is a pre-existing issue, but does mcp47feb02_common_probe() miss a
Power-On Reset (POR) delay after enabling the VDD regulator?

Looking at the shared probe function in drivers/iio/dac/mcp47feb02-core.c:

    ret = devm_regulator_get_enable_read_voltage(dev, "vdd");
    if (ret < 0)
        return ret;

    /* ... vref initialization ... */

    ret = mcp47feb02_init_ctrl_regs(data);

When devm_regulator_get_enable_read_voltage() cold-starts the VDD supply
for the first time, the device requires a typical 2ms (max 4ms) POR delay
before its internal state machine is ready to accept commands. 

Since the driver immediately proceeds to mcp47feb02_init_ctrl_regs() and
performs a regmap operation without any wait (e.g., usleep_range()), could
this cause the device to fail to probe or read garbage data on setups where
the driver is responsible for turning on the VDD regulator?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260909-mcp47feb02_refactor-v5-0-8b67bcab93d1@microchip.com?part=10