Commit 65299e8b authored by Hans de Goede's avatar Hans de Goede Committed by Dmitry Torokhov
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Input: elants_i2c - do not bind to i2c-hid compatible ACPI instantiated devices 

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: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210405202756.16830-1-hdegoede@redhat.com



Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 2531fdbf

drivers/input/touchscreen/elants_i2c.c

+42 −2
Original line number Diff line number Diff line
@@ -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;

	}