linux-kernel - Re: [PATCH 1/1] Input: rmi_i2c: introduce reset GPIO handling

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Message-ID: <8A6D08BB-B830-4275-B61B-15D367415D59@mainlining.org>
Date: Mon, 10 Feb 2025 06:48:24 +0100
From: Barnabás Czémán <barnabas.czeman@...nlining.org>
To: Felix Kaechele <felix@...chele.ca>,
 Dmitry Torokhov <dmitry.torokhov@...il.com>
CC: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] Input: rmi_i2c: introduce reset GPIO handling



On February 10, 2025 6:02:09 AM GMT+01:00, Felix Kaechele <felix@...chele.ca> wrote:
>Implement reset GPIO handling logic for the rmi_i2c driver. This logic
>is required for some mobile devices to successfully initialize the touch
>controller.
>
>The timings for the assertion of the reset GPIO were derived from the
>GPLv2+ licensed synaptics-dsx-v2.1 vendor driver release and research I
>conducted into downstream device tree sources. Values of 10ms to 20ms
>are commonly found.
>
>Tested-On: Motorola Moto G5 Plus (XT1685 "potter")
>
>Signed-off-by: Felix Kaechele <felix@...chele.ca>
>---
> drivers/input/rmi4/rmi_driver.c |  1 -
> drivers/input/rmi4/rmi_driver.h |  2 ++
> drivers/input/rmi4/rmi_i2c.c    | 23 +++++++++++++++++++++++
> 3 files changed, 25 insertions(+), 1 deletion(-)

Tested-by: Barnabás Czémán <barnabas.czeman@...nlining.org>

>
>diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
>index 2168b6cd7167..ff6aed6a11c1 100644
>--- a/drivers/input/rmi4/rmi_driver.c
>+++ b/drivers/input/rmi4/rmi_driver.c
>@@ -30,7 +30,6 @@
> #define RMI4_PAGE_MASK 0xFF00
> 
> #define RMI_DEVICE_RESET_CMD	0x01
>-#define DEFAULT_RESET_DELAY_MS	100
> 
> void rmi_free_function_list(struct rmi_device *rmi_dev)
> {
>diff --git a/drivers/input/rmi4/rmi_driver.h b/drivers/input/rmi4/rmi_driver.h
>index 3bfe9013043e..e01453bd680f 100644
>--- a/drivers/input/rmi4/rmi_driver.h
>+++ b/drivers/input/rmi4/rmi_driver.h
>@@ -16,6 +16,8 @@
> #define SYNAPTICS_INPUT_DEVICE_NAME "Synaptics RMI4 Touch Sensor"
> #define SYNAPTICS_VENDOR_ID 0x06cb
> 
>+#define DEFAULT_RESET_DELAY_MS	100
>+
> #define GROUP(_attrs) { \
> 	.attrs = _attrs,  \
> }
>diff --git a/drivers/input/rmi4/rmi_i2c.c b/drivers/input/rmi4/rmi_i2c.c
>index 3c0c5fd44702..beff566ca2c8 100644
>--- a/drivers/input/rmi4/rmi_i2c.c
>+++ b/drivers/input/rmi4/rmi_i2c.c
>@@ -4,6 +4,7 @@
>  * Copyright (c) 2011 Unixphere
>  */
> 
>+#include <linux/gpio/consumer.h>
> #include <linux/i2c.h>
> #include <linux/rmi.h>
> #include <linux/of.h>
>@@ -26,7 +27,9 @@
>  * @tx_buf_size: Size of the buffer
>  *
>  * @supplies: Array of voltage regulators
>+ * @reset_gpio: Reference to the reset GPIO
>  * @startup_delay: Milliseconds to pause after powering up the regulators
>+ * @reset_delay: Milliseconds to pause after resetting the device
>  */
> struct rmi_i2c_xport {
> 	struct rmi_transport_dev xport;
>@@ -39,7 +42,9 @@ struct rmi_i2c_xport {
> 	size_t tx_buf_size;
> 
> 	struct regulator_bulk_data supplies[2];
>+	struct gpio_desc *reset_gpio;
> 	u32 startup_delay;
>+	u32 reset_delay;
> };
> 
> #define RMI_PAGE_SELECT_REGISTER 0xff
>@@ -227,6 +232,15 @@ static int rmi_i2c_probe(struct i2c_client *client)
> 		return -ENODEV;
> 	}
> 
>+	rmi_i2c->reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
>+						      GPIOD_OUT_HIGH);
>+	if (IS_ERR(rmi_i2c->reset_gpio)) {
>+		error = PTR_ERR(rmi_i2c->reset_gpio);
>+		dev_err(&client->dev, "failed to get reset GPIO: %d\n", error);
>+		return error;
>+	}
>+	gpiod_set_consumer_name(rmi_i2c->reset_gpio, "rmi4 reset");
>+
> 	rmi_i2c->supplies[0].supply = "vdd";
> 	rmi_i2c->supplies[1].supply = "vio";
> 	error = devm_regulator_bulk_get(&client->dev,
>@@ -251,6 +265,15 @@ static int rmi_i2c_probe(struct i2c_client *client)
> 
> 	msleep(rmi_i2c->startup_delay);
> 
>+	if (rmi_i2c->reset_gpio) {
>+		of_property_read_u32(client->dev.of_node, "syna,reset-delay-ms",
>+				     &rmi_i2c->reset_delay);
>+		gpiod_set_value_cansleep(rmi_i2c->reset_gpio, 1);
>+		usleep_range(10000, 20000);
>+		gpiod_set_value_cansleep(rmi_i2c->reset_gpio, 0);
>+		msleep(rmi_i2c->reset_delay ?: DEFAULT_RESET_DELAY_MS);
>+	}
>+
> 	rmi_i2c->client = client;
> 	mutex_init(&rmi_i2c->page_mutex);
>