linux-kernel - Re: [PATCH v1 3/3] virtio-spi: Add virtio SPI driver.

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Message-ID: <20240229082224.2kh2scyjpielwx7v@vireshk-i7>
Date: Thu, 29 Feb 2024 13:52:24 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Harald Mommer <Harald.Mommer@...nsynergy.com>
Cc: virtio-dev@...ts.oasis-open.org, Haixu Cui <quic_haixcui@...cinc.com>,
	Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org, quic_ztu@...cinc.com,
	Matti Moell <Matti.Moell@...nsynergy.com>,
	Mikhail Golubev <Mikhail.Golubev@...nsynergy.com>
Subject: Re: [PATCH v1 3/3] virtio-spi: Add virtio SPI driver.

On 28-02-24, 15:27, Harald Mommer wrote:
> +static int virtio_spi_probe(struct virtio_device *vdev)
> +{
> +	struct device_node *np = vdev->dev.parent->of_node;
> +	struct virtio_spi_priv *priv;
> +	struct spi_controller *ctrl;
> +	int err;
> +	u32 bus_num;
> +	u16 csi;
> +
> +	ctrl = devm_spi_alloc_host(&vdev->dev, sizeof(*priv));
> +	if (!ctrl) {
> +		dev_err(&vdev->dev, "Kernel memory exhausted in %s()\n",
> +			__func__);

The print can be dropped I guess.

> +		return -ENOMEM;
> +	}
> +
> +	priv = spi_controller_get_devdata(ctrl);
> +	priv->vdev = vdev;
> +	vdev->priv = priv;
> +	dev_set_drvdata(&vdev->dev, ctrl);
> +
> +	init_completion(&priv->spi_req.completion);
> +
> +	err = of_property_read_u32(np, "spi,bus-num", &bus_num);
> +	if (!err && bus_num <= S16_MAX)
> +		ctrl->bus_num = (s16)bus_num;
> +
> +	virtio_spi_read_config(vdev);
> +
> +	/* Method to do a single SPI transfer */

The comments for obvious statements are normally not required. There
are a couple of them here.

> +	ctrl->transfer_one = virtio_spi_transfer_one;
> +
> +	/* Initialize virtqueues */
> +	err = virtio_spi_find_vqs(priv);
> +	if (err) {
> +		dev_err(&vdev->dev, "Cannot setup virtqueues\n");

Maybe "Failed to" instead of "Cannot" ?

> +		return err;
> +	}
> +
> +	err = spi_register_controller(ctrl);
> +	if (err) {
> +		dev_err(&vdev->dev, "Cannot register controller\n");
> +		goto err_return;
> +	}
> +
> +	board_info.max_speed_hz = priv->max_freq_hz;
> +	/* spi_new_device() currently does not use bus_num but better set it */
> +	board_info.bus_num = (u16)ctrl->bus_num;
> +
> +	/* Add chip selects to controller */
> +	for (csi = 0; csi < ctrl->num_chipselect; csi++) {
> +		dev_dbg(&vdev->dev, "Setting up CS=%u\n", csi);
> +		board_info.chip_select = csi;

Maybe a blank line here.

> +		/* TODO: Discuss setting of board_info.mode */
> +		if (!(priv->mode_func_supported & VIRTIO_SPI_CS_HIGH))
> +			board_info.mode = SPI_MODE_0;
> +		else
> +			board_info.mode = SPI_MODE_0 | SPI_CS_HIGH;

and here to improve readability.

> +		if (!spi_new_device(ctrl, &board_info)) {
> +			dev_err(&vdev->dev, "Cannot setup device %u\n", csi);
> +			spi_unregister_controller(ctrl);
> +			err = -ENODEV;
> +			goto err_return;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_return:
> +	vdev->config->del_vqs(vdev);
> +	return err;
> +}
> +
> +static void virtio_spi_remove(struct virtio_device *vdev)
> +{
> +	struct spi_controller *ctrl = dev_get_drvdata(&vdev->dev);
> +
> +	/* Order: 1.) unregister controller, 2.) remove virtqueue */

Not sure if this comment is required or not, since we don't add
similar ones while registering.

> +	spi_unregister_controller(ctrl);
> +	virtio_spi_del_vq(vdev);
> +}

Other than that.

Reviewed-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh