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    Subject[PATCH 5.12 13/45] Input: elants_i2c - do not bind to i2c-hid compatible ACPI instantiated devices
    Date
    From: Hans de Goede <hdegoede@redhat.com>

    [ Upstream commit 65299e8bfb24774e6340e93ae49f6626598917c8 ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 5f7706febcb0..17540bdb1eaf 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;
    }

    --
    2.30.2


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