linux-kernel - Re: [alsa-devel] [PATCH 06/10] mfd: Add core driver for AD242x A2B transceivers

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Date:   Tue, 17 Dec 2019 13:16:04 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Daniel Mack <daniel@...que.org>, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-clk@...r.kernel.org
Cc:     lars@...afoo.de, sboyd@...nel.org, mturquette@...libre.com,
        robh+dt@...nel.org, broonie@...nel.org, pascal.huerst@...il.com,
        lee.jones@...aro.org
Subject: Re: [alsa-devel] [PATCH 06/10] mfd: Add core driver for AD242x A2B
 transceivers


> +config MFD_AD242X
> +	bool "Analog Devices AD242x A2B support"
> +	select MFD_CORE
> +	select REGMAP_I2C
> +	depends on I2C=y && OF

is there a specific reason why I2C needs to be built-in (as opposed to 'm')?

> +/* See Table 3-2 in the datasheet */

is the datasheet public? I thought it was only available under NDA.

> +	master->sync_clk = devm_clk_get(dev, "sync");
> +	if (IS_ERR(master->sync_clk)) {
> +		ret = PTR_ERR(master->sync_clk);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dev, "failed to get sync clk: %d\n", ret);
> +
> +		return ret;
> +	}
> +
> +	if (of_property_read_u32(dev->of_node, "clock-frequency",
> +				 &master->sync_clk_rate)) {
> +		ret = clk_set_rate(master->sync_clk, master->sync_clk_rate);

shouldn't you check the rate before setting it?

> +		if (ret < 0) {
> +			dev_err(dev, "Cannot set sync clock rate: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	master->sync_clk_rate = clk_get_rate(master->sync_clk);
> +	if (master->sync_clk_rate != 44100 && master->sync_clk_rate != 48000) {
> +		dev_err(dev, "SYNC clock rate %d is invalid\n",
> +			master->sync_clk_rate);
> +		return -EINVAL;
> +	}

this is a bit odd, you set the rate in case there is a property but get 
it anyways. the last block could be an else?

> +
> +	ret = clk_prepare_enable(master->sync_clk);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to enable sync clk: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Master node setup */
> +
> +	ret = regmap_write(regmap, AD242X_CONTROL,
> +			   AD242X_CONTROL_MSTR | AD242X_CONTROL_SOFTRST);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ad242x_wait_for_irq(master, &master->run_completion, 10);

what is 10?


> +static int ad242x_master_remove(struct i2c_client *i2c)
> +{
> +	struct ad242x_master *master = i2c_get_clientdata(i2c);
> +
> +	if (master->sync_clk)
> +		clk_disable_unprepare(master->sync_clk);

earlier you tested for IS_ERR(master->sync_clk)?

> +	for (i = 0; i < 4; i++) {

what is 4? 4 hops?