[PATCH AUTOSEL 5.7 177/274] platform/x86: intel-vbtn: Do not advertise switches to userspace if they are not there

[Sasha Levin]

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

[ Upstream commit 990fbb48067bf8cfa34b7d1e6e1674eaaef2f450 ]

Commit de9647efeaa9 ("platform/x86: intel-vbtn: Only activate tablet mode
switch on 2-in-1's") added a DMI chassis-type check to avoid accidentally
reporting SW_TABLET_MODE = 1 to userspace on laptops (specifically on the
Dell XPS 9360), to avoid e.g. userspace ignoring touchpad events because
userspace thought the device was in tablet-mode.

But if we are not getting the initial status of the switch because the
device does not have a tablet mode, then we really should not advertise
the presence of a tablet-mode switch to userspace at all, as userspace may
use the mere presence of this switch for certain heuristics.

Fixes: de9647efeaa9 ("platform/x86: intel-vbtn: Only activate tablet mode 
switch on 2-in-1's")
Signed-off-by: Hans de Goede <hdego...@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevche...@linux.intel.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/platform/x86/intel-vbtn.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/platform/x86/intel-vbtn.c 
b/drivers/platform/x86/intel-vbtn.c
index 634096cef21a..500fae82e12c 100644
--- a/drivers/platform/x86/intel-vbtn.c
+++ b/drivers/platform/x86/intel-vbtn.c
@@ -55,6 +55,7 @@ static const struct key_entry intel_vbtn_switchmap[] = {
 struct intel_vbtn_priv {
        struct key_entry keymap[KEYMAP_LEN];
        struct input_dev *input_dev;
+       bool has_switches;
        bool wakeup_mode;
 };
 
@@ -70,7 +71,7 @@ static int intel_vbtn_input_setup(struct platform_device 
*device)
                keymap_len += ARRAY_SIZE(intel_vbtn_keymap);
        }
 
-       if (true) {
+       if (priv->has_switches) {
                memcpy(&priv->keymap[keymap_len], intel_vbtn_switchmap,
                       ARRAY_SIZE(intel_vbtn_switchmap) *
                       sizeof(struct key_entry));
@@ -138,16 +139,12 @@ static void notify_handler(acpi_handle handle, u32 event, 
void *context)
 
 static void detect_tablet_mode(struct platform_device *device)
 {
-       const char *chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
        struct intel_vbtn_priv *priv = dev_get_drvdata(&device->dev);
        acpi_handle handle = ACPI_HANDLE(&device->dev);
        unsigned long long vgbs;
        acpi_status status;
        int m;
 
-       if (!(chassis_type && strcmp(chassis_type, "31") == 0))
-               return;
-
        status = acpi_evaluate_integer(handle, "VGBS", NULL, &vgbs);
        if (ACPI_FAILURE(status))
                return;
@@ -158,6 +155,19 @@ static void detect_tablet_mode(struct platform_device 
*device)
        input_report_switch(priv->input_dev, SW_DOCK, m);
 }
 
+static bool intel_vbtn_has_switches(acpi_handle handle)
+{
+       const char *chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
+       unsigned long long vgbs;
+       acpi_status status;
+
+       if (!(chassis_type && strcmp(chassis_type, "31") == 0))
+               return false;
+
+       status = acpi_evaluate_integer(handle, "VGBS", NULL, &vgbs);
+       return ACPI_SUCCESS(status);
+}
+
 static int intel_vbtn_probe(struct platform_device *device)
 {
        acpi_handle handle = ACPI_HANDLE(&device->dev);
@@ -176,13 +186,16 @@ static int intel_vbtn_probe(struct platform_device 
*device)
                return -ENOMEM;
        dev_set_drvdata(&device->dev, priv);
 
+       priv->has_switches = intel_vbtn_has_switches(handle);
+
        err = intel_vbtn_input_setup(device);
        if (err) {
                pr_err("Failed to setup Intel Virtual Button\n");
                return err;
        }
 
-       detect_tablet_mode(device);
+       if (priv->has_switches)
+               detect_tablet_mode(device);
 
        status = acpi_install_notify_handler(handle,
                                             ACPI_DEVICE_NOTIFY,
-- 
2.25.1