linux-kernel - Re: [PATCH v5 1/2] HID: hid-goodix: Add Goodix HID-over-SPI driver

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Message-ID: <ZoW4_hctu_cSiKA5@google.com>
Date: Wed, 3 Jul 2024 13:47:58 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Charles Wang <charles.goodix@...il.com>
Cc: dan.carpenter@...aro.org, conor@...nel.org, robh@...nel.org,
	dianders@...omium.org, krzk+dt@...nel.org, jikos@...nel.org,
	bentiss@...nel.org, hbarnor@...omium.org,
	linux-input@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] HID: hid-goodix: Add Goodix HID-over-SPI driver

Hi Charles,

On Tue, Jun 18, 2024 at 04:44:53PM +0800, Charles Wang wrote:
> This patch introduces a new driver to support the Goodix GT7986U
> touch controller. This device is not compatible with Microsoft's
> HID-over-SPI protocol and therefore needs to implement its own
> flavor. The data reported is packaged according to the HID
> protocol but uses SPI for communication to improve speed. This
> enables the device to transmit not only coordinate data but also
> corresponding raw data that can be accessed by user-space programs
> through the hidraw interface. The raw data can be utilized for
> functions like palm rejection, thereby improving the touch experience.
> 
> Key features:
> - Device connection confirmation and initialization
> - IRQ-based event reporting to the input subsystem
> - Support for HIDRAW operations (GET_REPORT and SET_REPORT)

This looks reasonable good, so:

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

A couple of suggestions/nits below:

> +static int goodix_spi_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct goodix_ts_data *ts;
> +	int error;
> +
> +	/* init spi_device */
> +	spi->mode            = SPI_MODE_0;
> +	spi->bits_per_word   = 8;
> +	error = spi_setup(spi);
> +	if (error)
> +		return error;
> +
> +	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> +	if (!ts)
> +		return -ENOMEM;
> +

If you do:

	ts->event_buf = devm_kmalloc(dev, <some nominal size>, GFP_KERNEL);

here and use devm_krealloc() once you figure the true size of event
buffer you can stop calling kfree() by hand on remove.

> +	mutex_init(&ts->hid_request_lock);
> +	spi_set_drvdata(spi, ts);
> +	ts->spi = spi;
> +	ts->dev = dev;
> +	ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(ts->reset_gpio))
> +		return dev_err_probe(dev, PTR_ERR(ts->reset_gpio),
> +				     "failed to request reset gpio\n");
> +
> +	error = device_property_read_u32(dev, "goodix,hid-report-addr",
> +					 &ts->hid_report_addr);
> +	if (error)
> +		return dev_err_probe(dev, error,
> +				     "failed get hid report addr\n");
> +
> +	error = goodix_dev_confirm(ts);
> +	if (error)
> +		return error;
> +
> +	/* Waits 150ms for firmware to fully boot */
> +	msleep(GOODIX_NORMAL_RESET_DELAY_MS);
> +
> +	error = goodix_hid_init(ts);
> +	if (error) {
> +		dev_err(dev, "failed init hid device");
> +		return error;
> +	}
> +
> +	error = devm_request_threaded_irq(&ts->spi->dev, ts->spi->irq,
> +					  NULL, goodix_hid_irq, IRQF_ONESHOT,
> +					  "goodix_spi_hid", ts);
> +	if (error) {
> +		dev_err(ts->dev, "could not register interrupt, irq = %d, %d",
> +			ts->spi->irq, error);
> +		goto err_destroy_hid;
> +	}
> +
> +	return 0;
> +
> +err_destroy_hid:
> +	hid_destroy_device(ts->hid);
> +	return error;
> +}
> +
> +static void goodix_spi_remove(struct spi_device *spi)
> +{
> +	struct goodix_ts_data *ts = spi_get_drvdata(spi);
> +
> +	disable_irq(spi->irq);
> +	hid_destroy_device(ts->hid);
> +	kfree(ts->event_buf);
> +}
> +
> +static void goodix_spi_shutdown(struct spi_device *spi)
> +{
> +	struct goodix_ts_data *ts = spi_get_drvdata(spi);
> +
> +	disable_irq(spi->irq);
> +	hid_destroy_device(ts->hid);

Do we really need shutdown() method? It is very rarely that it is
needed.

> +}
> +
> +static int goodix_spi_set_power(struct goodix_ts_data *ts, int power_state)
> +{
> +	u8 power_control_cmd[] = {0x00, 0x00, 0x00, 0x87, 0x02, 0x00, 0x08};
> +	int error;
> +
> +	/* value 0 for power on, 1 for power sleep */
> +	power_control_cmd[5] = power_state;
> +
> +	guard(mutex)(&ts->hid_request_lock);
> +	error = goodix_spi_write(ts, ts->hid_report_addr, power_control_cmd,
> +				 sizeof(power_control_cmd));
> +	if (error) {
> +		dev_err(ts->dev, "failed set power mode: %s",
> +			power_state == GOODIX_SPI_POWER_ON ? "on" : "sleep");
> +		return error;
> +	}
> +	return 0;
> +}
> +
> +static int goodix_spi_suspend(struct device *dev)
> +{
> +	struct goodix_ts_data *ts = dev_get_drvdata(dev);
> +	int error;
> +
> +	error = goodix_spi_set_power(ts, GOODIX_SPI_POWER_SLEEP);
> +	disable_irq(ts->spi->irq);

Can disable_irq() be called first?

Thanks.

-- 
Dmitry