From 65299e8bfb24774e6340e93ae49f6626598917c8 Mon Sep 17 00:00:00 2001

From: Hans de Goede <hdegoede@redhat.com>

Date: Fri, 9 Apr 2021 22:29:07 -0700

Subject: [PATCH] Input: elants_i2c - do not bind to i2c-hid compatible ACPI instantiated devices

Git-commit: 65299e8bfb24774e6340e93ae49f6626598917c8

Patch-mainline: v5.13-rc1

References: git-fixes

Several users have been reporting that elants_i2c gives several errors

during probe and that their touchscreen does not work on their Lenovo AMD

based laptops with a touchscreen with a ELAN0001 ACPI hardware-id:

[    0.550596] elants_i2c i2c-ELAN0001:00: i2c-ELAN0001:00 supply vcc33 not found, using dummy regulator

[    0.551836] elants_i2c i2c-ELAN0001:00: i2c-ELAN0001:00 supply vccio not found, using dummy regulator

[    0.560932] elants_i2c i2c-ELAN0001:00: elants_i2c_send failed (77 77 77 77): -121

[    0.562427] elants_i2c i2c-ELAN0001:00: software reset failed: -121

[    0.595925] elants_i2c i2c-ELAN0001:00: elants_i2c_send failed (77 77 77 77): -121

[    0.597974] elants_i2c i2c-ELAN0001:00: software reset failed: -121

[    0.621893] elants_i2c i2c-ELAN0001:00: elants_i2c_send failed (77 77 77 77): -121

[    0.622504] elants_i2c i2c-ELAN0001:00: software reset failed: -121

[    0.632650] elants_i2c i2c-ELAN0001:00: elants_i2c_send failed (4d 61 69 6e): -121

[    0.634256] elants_i2c i2c-ELAN0001:00: boot failed: -121

[    0.699212] elants_i2c i2c-ELAN0001:00: invalid 'hello' packet: 00 00 ff ff

[    1.630506] elants_i2c i2c-ELAN0001:00: Failed to read fw id: -121

[    1.645508] elants_i2c i2c-ELAN0001:00: unknown packet 00 00 ff ff

Despite these errors, the elants_i2c driver stays bound to the device

(it returns 0 from its probe method despite the errors), blocking the

i2c-hid driver from binding.

Manually unbinding the elants_i2c driver and binding the i2c-hid driver

makes the touchscreen work.

Check if the ACPI-fwnode for the touchscreen contains one of the i2c-hid

compatiblity-id strings and if it has the I2C-HID spec's DSM to get the

HID descriptor address, If it has both then make elants_i2c not bind,

so that the i2c-hid driver can bind.

This assumes that non of the (older) elan touchscreens which actually

need the elants_i2c driver falsely advertise an i2c-hid compatiblity-id

+ DSM in their ACPI-fwnodes. If some of them actually do have this

false advertising, then this change may lead to regressions.

While at it also drop the unnecessary DEVICE_NAME prefixing of the

"I2C check functionality error", dev_err already outputs the driver-name.

Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=207759

Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Link: https://lore.kernel.org/r/20210405202756.16830-1-hdegoede@redhat.com

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/input/touchscreen/elants_i2c.c | 44 ++++++++++++++++++++++++--

 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c

index 4c2b579f6c8b..36cf5694bfcc 100644

--- a/drivers/input/touchscreen/elants_i2c.c

+++ b/drivers/input/touchscreen/elants_i2c.c

@@ -38,6 +38,7 @@

 #include <linux/of.h>

 #include <linux/gpio/consumer.h>

 #include <linux/regulator/consumer.h>

+#include <linux/uuid.h>

 #include <asm/unaligned.h>

 /* Device, Driver information */

@@ -1334,6 +1335,40 @@ static void elants_i2c_power_off(void *_data)

 	}

 }

+#ifdef CONFIG_ACPI

+static const struct acpi_device_id i2c_hid_ids[] = {

+	{"ACPI0C50", 0 },

+	{"PNP0C50", 0 },

+	{ },

+};

+

+static const guid_t i2c_hid_guid =

+	GUID_INIT(0x3CDFF6F7, 0x4267, 0x4555,

+		  0xAD, 0x05, 0xB3, 0x0A, 0x3D, 0x89, 0x38, 0xDE);

+

+static bool elants_acpi_is_hid_device(struct device *dev)

+{

+	acpi_handle handle = ACPI_HANDLE(dev);

+	union acpi_object *obj;

+

+	if (acpi_match_device_ids(ACPI_COMPANION(dev), i2c_hid_ids))

+		return false;

+

+	obj = acpi_evaluate_dsm_typed(handle, &i2c_hid_guid, 1, 1, NULL, ACPI_TYPE_INTEGER);

+	if (obj) {

+		ACPI_FREE(obj);

+		return true;

+	}

+

+	return false;

+}

+#else

+static bool elants_acpi_is_hid_device(struct device *dev)

+{

+	return false;

+}

+#endif

+

 static int elants_i2c_probe(struct i2c_client *client,

 			    const struct i2c_device_id *id)

 {

@@ -1342,9 +1377,14 @@ static int elants_i2c_probe(struct i2c_client *client,

 	unsigned long irqflags;

 	int error;

+	/* Don't bind to i2c-hid compatible devices, these are handled by the i2c-hid drv. */

+	if (elants_acpi_is_hid_device(&client->dev)) {

+		dev_warn(&client->dev, "This device appears to be an I2C-HID device, not binding\n");

+		return -ENODEV;

+	}

+

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {

-		dev_err(&client->dev,

-			"%s: i2c check functionality error\n", DEVICE_NAME);

+		dev_err(&client->dev, "I2C check functionality error\n");

 		return -ENXIO;

 	}

-- 

2.26.2