[PATCH AUTOSEL 6.15 7/8] platform/x86: asus-nb-wmi: add DMI quirk for ASUS Zenbook Duo UX8406CA

[Sasha Levin <sashal@kernel.org>]

From: Rahul Chandra <rahul@chandra.net>

[ Upstream commit 7dc6b2d3b5503bcafebbeaf9818112bf367107b4 ]

Add a DMI quirk entry for the ASUS Zenbook Duo UX8406CA 2025 model to use
the existing zenbook duo keyboard quirk.

Signed-off-by: Rahul Chandra <rahul@chandra.net>
Link: https://lore.kernel.org/r/20250624073301.602070-1-rahul@chandra.net
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

**YES**

This commit should be backported to stable kernel trees. Here's the
extensive explanation:

## Analysis of the Code Changes

The commit adds a simple DMI quirk entry for the ASUS Zenbook Duo
UX8406CA:

```c
+       {
+               .callback = dmi_matched,
+               .ident = "ASUS Zenbook Duo UX8406CA",
+               .matches = {
+                       DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER
INC."),
+                       DMI_MATCH(DMI_PRODUCT_NAME, "UX8406CA"),
+               },
+               .driver_data = &quirk_asus_zenbook_duo_kbd,
+       },
```

This applies the existing `quirk_asus_zenbook_duo_kbd` to the UX8406CA
model.

## Why This Is a Bug Fix, Not Just Hardware Enablement

Based on my analysis of the kernel repository, the
`quirk_asus_zenbook_duo_kbd` was introduced to fix a specific hardware
issue where:

1. **The keyboard emits spurious wireless disable keypresses** when
   placed on the laptop's secondary display
2. **This causes unexpected WiFi disconnections** via the rfkill system
3. **The keyboard doesn't actually have wireless toggle functionality**,
   so these events are always spurious

## Evidence Supporting Backporting

1. **Fixes User-Impacting Bug**: Without this quirk, users experience
   unexpected WiFi disconnections when using their keyboard normally,
   which significantly impacts usability.

2. **Follows Established Pattern**: The commit follows the exact pattern
   of the previous UX8406MA support (commit 9286dfd5735b), which
   addressed the same issue for a similar model.

3. **Minimal Risk**: The change is:
   - Only 9 lines of code
   - Isolated to specific hardware (only affects UX8406CA)
   - Uses existing, tested infrastructure
   - Cannot affect other systems due to DMI matching

4. **Similar to Other Backported Commits**: Looking at the reference
   commits:
   - Commit 2b1cb70 (adding support for ALS on UX430UQ) was backported
   - Commit ac16dfa (reverting GA401/GA502 quirks) was backported
   - Commit 82a7228 (adding tablet mode quirk for ROG Flow X13) was
     backported

5. **Clear Bug Fix Nature**: Unlike commit 79493de (making use of
   dmi->ident) which was NOT backported because it was just a code
   improvement, this commit actually fixes broken functionality.

## Comparison with Reference Commits

This commit is most similar to:
- **Commit 2b1cb70** (YES): Added device-specific quirk to fix
  functionality
- **Commit 82a7228** (YES): Added quirk to fix hardware-specific issue
- **Commit 25390f8** (YES): Added device support to fix existing
  hardware

And dissimilar to:
- **Commit 79493de** (NO): Code refactoring without functional impact

## Conclusion

This commit meets all criteria for stable backporting:
- Fixes a real bug affecting users
- Small, contained change
- Low risk of regression
- Follows established patterns
- Only affects specific hardware

The commit should be backported to stable kernels that contain the
`quirk_asus_zenbook_duo_kbd` infrastructure (6.11+).

 drivers/platform/x86/asus-nb-wmi.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/platform/x86/asus-nb-wmi.c b/drivers/platform/x86/asus-nb-wmi.c
index 3f8b2a324efdf..f84c3d03c1de7 100644
--- a/drivers/platform/x86/asus-nb-wmi.c
+++ b/drivers/platform/x86/asus-nb-wmi.c
@@ -530,6 +530,15 @@ static const struct dmi_system_id asus_quirks[] = {
 		},
 		.driver_data = &quirk_asus_zenbook_duo_kbd,
 	},
+	{
+		.callback = dmi_matched,
+		.ident = "ASUS Zenbook Duo UX8406CA",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "UX8406CA"),
+		},
+		.driver_data = &quirk_asus_zenbook_duo_kbd,
+	},
 	{},
 };
 
-- 
2.39.5