[PATCH fixes v3] platform/x86: ideapad-laptop: Disable touchpad_switch for ELAN0634

[Jiaxun Yang]

Newer ideapads (e.g.: Yoga 14s, 720S 14) come with ELAN0634 touchpad do not
use EC to switch touchpad.

Reading VPCCMD_R_TOUCHPAD will return zero thus touchpad may be blocked
unexpectedly.
Writing VPCCMD_W_TOUCHPAD may cause a spurious key press.

Add has_touchpad_switch to workaround these machines.

Signed-off-by: Jiaxun Yang <jiaxun.y...@flygoat.com>
Cc: sta...@vger.kernel.org # 5.4+
--
v2: Specify touchpad to ELAN0634
v3: Stupid missing ! in v2
---
 drivers/platform/x86/ideapad-laptop.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/ideapad-laptop.c 
b/drivers/platform/x86/ideapad-laptop.c
index 7598cd46cf60..427970b3b0da 100644
--- a/drivers/platform/x86/ideapad-laptop.c
+++ b/drivers/platform/x86/ideapad-laptop.c
@@ -92,6 +92,7 @@ struct ideapad_private {
        struct dentry *debug;
        unsigned long cfg;
        bool has_hw_rfkill_switch;
+       bool has_touchpad_switch;
        const char *fnesc_guid;
 };
 
@@ -535,7 +536,9 @@ static umode_t ideapad_is_visible(struct kobject *kobj,
        } else if (attr == &dev_attr_fn_lock.attr) {
                supported = acpi_has_method(priv->adev->handle, "HALS") &&
                        acpi_has_method(priv->adev->handle, "SALS");
-       } else
+       } else if (attr == &dev_attr_touchpad.attr)
+               supported = priv->has_touchpad_switch;
+       else
                supported = true;
 
        return supported ? attr->mode : 0;
@@ -867,6 +870,9 @@ static void ideapad_sync_touchpad_state(struct 
ideapad_private *priv)
 {
        unsigned long value;
 
+       if (!priv->has_touchpad_switch)
+               return;
+
        /* Without reading from EC touchpad LED doesn't switch state */
        if (!read_ec_data(priv->adev->handle, VPCCMD_R_TOUCHPAD, &value)) {
                /* Some IdeaPads don't really turn off touchpad - they only
@@ -989,6 +995,9 @@ static int ideapad_acpi_add(struct platform_device *pdev)
        priv->platform_device = pdev;
        priv->has_hw_rfkill_switch = dmi_check_system(hw_rfkill_list);
 
+       /* Most ideapads with ELAN0634 touchpad don't use EC touchpad switch */
+       priv->has_touchpad_switch = !acpi_dev_present("PNP0C50", "ELAN0634", 
-1);
+
        ret = ideapad_sysfs_init(priv);
        if (ret)
                return ret;
@@ -1006,6 +1015,10 @@ static int ideapad_acpi_add(struct platform_device *pdev)
        if (!priv->has_hw_rfkill_switch)
                write_ec_cmd(priv->adev->handle, VPCCMD_W_RF, 1);
 
+       /* The same for Touchpad */
+       if (!priv->has_touchpad_switch)
+               write_ec_cmd(priv->adev->handle, VPCCMD_W_TOUCHPAD, 1);
+
        for (i = 0; i < IDEAPAD_RFKILL_DEV_NUM; i++)
                if (test_bit(ideapad_rfk_data[i].cfgbit, &priv->cfg))
                        ideapad_register_rfkill(priv, i);
-- 
2.30.0