For a broken touchpad, it may take several months or longer to be fixed. Polling mode could be a fallback solution for enthusiastic Linux users when they have a new laptop. It also acts like a debugging feature. If polling mode works for a broken touchpad, we can almost be certain the root cause is related to the interrupt or power setting.

This patch could fix touchpads of Lenovo AMD gaming laptops including Legion-5 15ARH05 (R7000), Legion-5P (R7000P) and IdeaPad Gaming 3 15ARH05.

When polling mode is enabled, an I2C device can't wake up the suspended system since enable/disable_irq_wake is invalid for polling mode.

Three module parameters are added to i2c-hid, - polling_mode: by default set to 0, i.e., polling is disabled - polling_interval_idle_ms: the polling internal when the touchpad is idle, default to 10ms - polling_interval_active_us: the polling internal when the touchpad is active, default to 4000us

User can change the last two runtime polling parameter by writing to /sys/module/i2c_hid/parameters/polling_interval_{idle_ms,active_us}.

Note xf86-input-synaptics doesn't work well with this polling mode for the Synaptics touchpad. The Synaptics touchpad would often locks into scroll mode when using multitouch gestures [1]. One remedy is to decrease the polling interval.

Thanks to Barnabás's thorough review of this patch and the useful feedback!

[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1887190/comments/235

Cc: stable@vger.kernel.org Cc: Barnabás Pőcze pobrn@protonmail.com BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1887190 Signed-off-by: Coiby Xu coiby.xu@gmail.com --- drivers/hid/i2c-hid/i2c-hid-core.c | 152 +++++++++++++++++++++++++++-- 1 file changed, 142 insertions(+), 10 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c index aeff1ffb0c8b..f25503f31ccf 100644 --- a/drivers/hid/i2c-hid/i2c-hid-core.c +++ b/drivers/hid/i2c-hid/i2c-hid-core.c @@ -36,6 +36,8 @@ #include <linux/hid.h> #include <linux/mutex.h> #include <linux/acpi.h> +#include <linux/kthread.h> +#include <linux/gpio/driver.h> #include <linux/of.h> #include <linux/regulator/consumer.h>

@@ -60,6 +62,25 @@ #define I2C_HID_PWR_ON 0x00 #define I2C_HID_PWR_SLEEP 0x01

+/* polling mode */ +#define I2C_HID_POLLING_DISABLED 0 +#define I2C_HID_POLLING_GPIO_PIN 1 +#define I2C_HID_POLLING_INTERVAL_ACTIVE_US 4000 +#define I2C_HID_POLLING_INTERVAL_IDLE_MS 10 + +static u8 polling_mode; +module_param(polling_mode, byte, 0444); +MODULE_PARM_DESC(polling_mode, "How to poll (default=0) - 0 disabled; 1 based on GPIO pin's status"); + +static unsigned int polling_interval_active_us __read_mostly = I2C_HID_POLLING_INTERVAL_ACTIVE_US; +module_param(polling_interval_active_us, uint, 0644); +MODULE_PARM_DESC(polling_interval_active_us, + "Poll every {polling_interval_active_us} us when the touchpad is active (default=" __stringify(I2C_HID_POLLING_INTERVAL_ACTIVE_US) " us)"); + +static unsigned int polling_interval_idle_ms __read_mostly = I2C_HID_POLLING_INTERVAL_IDLE_MS; +module_param(polling_interval_idle_ms, uint, 0644); +MODULE_PARM_DESC(polling_interval_idle_ms, + "Poll every {polling_interval_idle_ms} ms when the touchpad is idle (default=" __stringify(I2C_HID_POLLING_INTERVAL_IDLE_MS) "ms)"); /* debug option */ static bool debug; module_param(debug, bool, 0444); @@ -158,6 +179,10 @@ struct i2c_hid {

struct i2c_hid_platform_data pdata;

+ struct task_struct *polling_thread; + unsigned long irq_trigger_type; + struct irq_desc *irq_desc; + bool irq_wake_enabled; struct mutex reset_lock; }; @@ -772,7 +797,9 @@ static int i2c_hid_start(struct hid_device *hid) i2c_hid_free_buffers(ihid);

ret = i2c_hid_alloc_buffers(ihid, bufsize); - enable_irq(client->irq); + + if (polling_mode == I2C_HID_POLLING_DISABLED) + enable_irq(client->irq);

if (ret) return ret; @@ -814,6 +841,96 @@ struct hid_ll_driver i2c_hid_ll_driver = { }; EXPORT_SYMBOL_GPL(i2c_hid_ll_driver);

+static int get_gpio_pin_state(struct irq_desc *irq_desc) +{ + struct gpio_chip *gc = irq_data_get_irq_chip_data(&irq_desc->irq_data); + int value; + + /* + * This part of code is borrowed from gpiod_get_raw_value_commit in + * drivers/gpio/gpiolib.c. Ideally, gpiod_get_value_cansleep can be re-used + * instead but there is no API of converting (struct irq_desc *) to + * (struct gpio_desc*). + */ + value = gc->get ? gc->get(gc, irq_desc->irq_data.hwirq) : -EIO; + value = value < 0 ? value : !!value; + return value; +} + +static bool interrupt_line_active(struct i2c_hid *ihid) +{ + int status = get_gpio_pin_state(ihid->irq_desc); + struct i2c_client *client = ihid->client; + + if (status < 0) { + dev_dbg_ratelimited(&client->dev, + "Failed to get GPIO Interrupt line status for %s", + client->name); + return false; + } + /* + * According to Windows Precsiontion Touchpad's specs + * https://docs.microsoft.com/en-us/windows-hardware/design/component-guideline..., + * GPIO Interrupt Assertion Leve could be either ActiveLow or + * ActiveHigh. + */ + if (ihid->irq_trigger_type & IRQF_TRIGGER_LOW) + return !status; + + return status; +} + +static int i2c_hid_polling_thread(void *i2c_hid) +{ + struct i2c_hid *ihid = i2c_hid; + unsigned int polling_interval_idle; + + while (!kthread_should_stop()) { + while (interrupt_line_active(i2c_hid) && + !test_bit(I2C_HID_READ_PENDING, &ihid->flags) && + !kthread_should_stop()) { + i2c_hid_get_input(ihid); + usleep_range(polling_interval_active_us, + polling_interval_active_us + 100); + } + /* + * re-calculate polling_interval_idle + * so the module parameters polling_interval_idle_ms can be + * changed dynamically through sysfs as polling_interval_active_us + */ + polling_interval_idle = polling_interval_idle_ms * 1000; + usleep_range(polling_interval_idle, + polling_interval_idle + 1000); + } + + return 0; +} + +static int i2c_hid_init_polling(struct i2c_hid *ihid) +{ + struct i2c_client *client = ihid->client; + + ihid->irq_trigger_type = irq_get_trigger_type(client->irq); + if (!ihid->irq_trigger_type) { + dev_dbg(&client->dev, + "Failed to get GPIO Interrupt Assertion Level, could not enable polling mode for %s", + client->name); + return -EINVAL; + } + + ihid->polling_thread = kthread_create(i2c_hid_polling_thread, ihid, + "I2C HID polling thread"); + + if (IS_ERR(ihid->polling_thread)) { + dev_err(&client->dev, "Failed to create I2C HID polling thread"); + return PTR_ERR(ihid->polling_thread); + } + + ihid->irq_desc = irq_to_desc(client->irq); + wake_up_process(ihid->polling_thread); + return 0; +} + static int i2c_hid_init_irq(struct i2c_client *client) { struct i2c_hid *ihid = i2c_get_clientdata(client); @@ -1014,6 +1131,15 @@ static void i2c_hid_fwnode_probe(struct i2c_client *client, pdata->post_power_delay_ms = val; }

+static void free_irq_or_stop_polling(struct i2c_client *client, + struct i2c_hid *ihid) +{ + if (polling_mode != I2C_HID_POLLING_DISABLED) + kthread_stop(ihid->polling_thread); + else + free_irq(client->irq, ihid); +} + static int i2c_hid_probe(struct i2c_client *client, const struct i2c_device_id *dev_id) { @@ -1109,7 +1235,11 @@ static int i2c_hid_probe(struct i2c_client *client, if (ret < 0) goto err_regulator;

- ret = i2c_hid_init_irq(client); + if (polling_mode != I2C_HID_POLLING_DISABLED) + ret = i2c_hid_init_polling(ihid); + else + ret = i2c_hid_init_irq(client); + if (ret < 0) goto err_regulator;

@@ -1148,7 +1278,7 @@ static int i2c_hid_probe(struct i2c_client *client, hid_destroy_device(hid);

err_irq: - free_irq(client->irq, ihid); + free_irq_or_stop_polling(client, ihid);

err_regulator: regulator_bulk_disable(ARRAY_SIZE(ihid->pdata.supplies), @@ -1165,7 +1295,7 @@ static int i2c_hid_remove(struct i2c_client *client) hid = ihid->hid; hid_destroy_device(hid);

- free_irq(client->irq, ihid); + free_irq_or_stop_polling(client, ihid);

if (ihid->bufsize) i2c_hid_free_buffers(ihid); @@ -1181,7 +1311,7 @@ static void i2c_hid_shutdown(struct i2c_client *client) struct i2c_hid *ihid = i2c_get_clientdata(client);

i2c_hid_set_power(client, I2C_HID_PWR_SLEEP); - free_irq(client->irq, ihid); + free_irq_or_stop_polling(client, ihid);

i2c_hid_acpi_shutdown(&client->dev); } @@ -1204,15 +1334,16 @@ static int i2c_hid_suspend(struct device *dev) /* Save some power */ i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);

- disable_irq(client->irq); + if (polling_mode == I2C_HID_POLLING_DISABLED) + disable_irq(client->irq);

- if (device_may_wakeup(&client->dev)) { + if (device_may_wakeup(&client->dev) && polling_mode == I2C_HID_POLLING_DISABLED) { wake_status = enable_irq_wake(client->irq); if (!wake_status) ihid->irq_wake_enabled = true; else hid_warn(hid, "Failed to enable irq wake: %d\n", - wake_status); + wake_status); } else { regulator_bulk_disable(ARRAY_SIZE(ihid->pdata.supplies), ihid->pdata.supplies); @@ -1229,7 +1360,7 @@ static int i2c_hid_resume(struct device *dev) struct hid_device *hid = ihid->hid; int wake_status;

- if (!device_may_wakeup(&client->dev)) { + if (!device_may_wakeup(&client->dev) || polling_mode != I2C_HID_POLLING_DISABLED) { ret = regulator_bulk_enable(ARRAY_SIZE(ihid->pdata.supplies), ihid->pdata.supplies); if (ret) @@ -1246,7 +1377,8 @@ static int i2c_hid_resume(struct device *dev) wake_status); }

- enable_irq(client->irq); + if (polling_mode == I2C_HID_POLLING_DISABLED) + enable_irq(client->irq);

/* Instead of resetting device, simply powers the device on. This * solves "incomplete reports" on Raydium devices 2386:3118 and