linux-kernel - Re: [PATCH v4 1/4] [media] platform: Add Synopsys Designware HDMI RX PHY e405 Driver

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Date:   Sun, 25 Jun 2017 23:13:05 +0200
From:   Sylwester Nawrocki <snawrocki@...nel.org>
To:     Jose Abreu <Jose.Abreu@...opsys.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org,
        Carlos Palminha <CARLOS.PALMINHA@...opsys.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hans.verkuil@...co.com>
Subject: Re: [PATCH v4 1/4] [media] platform: Add Synopsys Designware HDMI RX
 PHY e405 Driver

Hi Jose,

Thank you for addressing my review comments. Couple more suggestions below.

On 06/20/2017 07:26 PM, Jose Abreu wrote:
> This adds support for the Synopsys Designware HDMI RX PHY e405. This
> phy receives and decodes HDMI video that is delivered to a controller.

> +static int dw_phy_config(struct dw_phy_dev *dw_dev, unsigned char color_depth,
> +		bool hdmi2, bool scrambling)
> +{

> +	phy_reset(dw_dev, 1);
> +	phy_pddq(dw_dev, 1);
> +	phy_svsmode(dw_dev, 1);
> +
> +	phy_zcal_reset(dw_dev);
> +	do {
> +		udelay(1000);

Could be mdelay(1) or better e.g. usleep_range(1000, 1100);

> +		zcal_done = phy_zcal_done(dw_dev);
> +	} while (!zcal_done && timeout--);
> +
> +	if (!zcal_done) {
> +		dev_err(dw_dev->dev, "Zcal calibration failed\n");
> +		return -ETIMEDOUT;
> +	}

> +	return 0;
> +}

> +static int dw_phy_probe(struct platform_device *pdev)
> +{
> +	struct dw_phy_pdata *pdata = pdev->dev.platform_data;
> +	struct device *dev = &pdev->dev;
> +	struct dw_phy_dev *dw_dev;
> +	struct v4l2_subdev *sd;
> +	int ret;
> +
> +	dev_dbg(dev, "probe start\n");
> +
> +	/* Resource allocation */

This comment is not needed.

> +	dw_dev = devm_kzalloc(dev, sizeof(*dw_dev), GFP_KERNEL);
> +	if (!dw_dev)
> +		return -ENOMEM;
> +
> +	/* Resource initialization */

Ditto.

> +	if (!pdata) {
> +		dev_err(dev, "no platform data suplied\n");
> +		return -EINVAL;
> +	}
> +
> +	dw_dev->dev = dev;
> +	dw_dev->config = pdata;
> +	dw_dev->version = 405;

How about storing the version number in the dw_hdmi_phy_e405_id[] table
and retrieving it here with of_device_get_match_data() ?

> +	mutex_init(&dw_dev->lock);
> +
> +	/* Get config clock value */

The comment is not needed, it's clear from the code we are getting the clock 
and its rate.

> +	dw_dev->clk = devm_clk_get(dev, "cfg-clk");

As Rob suggested, it would be good to change name of the clock to just "cfg".

> +	if (IS_ERR(dw_dev->clk)) {
> +		dev_err(dev, "failed to get cfg-clk\n");
> +		return PTR_ERR(dw_dev->clk);
> +	}
> +
> +	ret = clk_prepare_enable(dw_dev->clk);
> +	if (ret) {
> +		dev_err(dev, "failed to enable cfg-clk\n");
> +		return ret;
> +	}
> +
> +	dw_dev->cfg_clk = clk_get_rate(dw_dev->clk) / 1000000;

1000000U ?

> +	if (!dw_dev->cfg_clk) {
> +		dev_err(dev, "invalid cfg-clk frequency\n");> +		ret = -EINVAL;
> +		goto err_clk;
> +	}
> +
> +	/* V4L2 initialization */
> +	sd = &dw_dev->sd;
> +	v4l2_subdev_init(sd, &dw_phy_sd_ops);
> +	strlcpy(sd->name, dev_name(dev), sizeof(sd->name));
> +	sd->dev = dev;
> +
> +	/* Force phy disabling */
> +	dw_dev->phy_enabled = true;
> +	dw_phy_disable(dw_dev);
> +
> +	/* Register subdev */
> +	ret = v4l2_async_register_subdev(sd);
> +	if (ret) {
> +		dev_err(dev, "failed to register subdev\n");
> +		goto err_clk;
> +	}
> +
> +	/* All done */

Superfluous comment.

> +	dev_set_drvdata(dev, sd);
> +	dev_info(dev, "driver probed (cfg-clk=%d)\n", dw_dev->cfg_clk);

This should be at dev_dbg() level.

> +	return 0;
> +
> +err_clk:
> +	clk_disable_unprepare(dw_dev->clk);
> +	return ret;
> +}
> +
> +static int dw_phy_remove(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;

The assignment here could be dropped and &pdev->dev used directly below.

> +	struct v4l2_subdev *sd = dev_get_drvdata(dev);

> +	struct dw_phy_dev *dw_dev = to_dw_dev(sd);
> +
> +	v4l2_async_unregister_subdev(sd);
> +	clk_disable_unprepare(dw_dev->clk);

> +	dev_info(dev, "driver removed\n");

This should be at dev_dbg() level or dropped entirely.

> +	return 0;
> +}
> +
> +static const struct of_device_id dw_hdmi_phy_e405_id[] = {
> +	{ .compatible = "snps,dw-hdmi-phy-e405" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, dw_hdmi_phy_e405_id);

--
Regards,
Sylwester