[PATCH AUTOSEL 6.16 04/85] platform/x86/amd: pmc: Add Lenovo Yoga 6 13ALC6 to pmc quirk list

[Sasha Levin <sashal@kernel.org>]

From: Mario Limonciello <mario.limonciello@amd.com>

[ Upstream commit 4ff3aeb664f7dfe824ba91ffb0b203397a8d431e ]

The Lenovo Yoga 6 13ACL6 82ND has a similar BIOS problem as other Lenovo
laptops from that vintage that causes a rather long resume from suspend.

Add it to the quirk list that manipulates the scratch register to avoid
the issue.

Reported-by: Adam Berglund <adam.f.berglund@hotmail.com>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4434
Tested-by: Adam Berglund <adam.f.berglund@hotmail.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Hans de Goede <hansg@kernel.org>
Link: https://lore.kernel.org/r/20250718172307.1928744-1-superm1@kernel.org
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>
---

LLM Generated explanations, may be completely bogus:

**YES**

This commit should be backported to stable kernel trees. Here's my
extensive analysis:

## Backport Justification

1. **Fixes a real user-impacting bug**: The commit addresses a BIOS
   firmware bug that causes "rather long resume from suspend" on the
   Lenovo Yoga 6 13ALC6 laptop. This is a significant usability issue
   that affects users of this specific hardware model during
   suspend/resume operations.

2. **Minimal and contained change**: The patch simply adds 8 lines to an
   existing DMI quirk table (lines 193-201 in the diff). It adds one new
   entry:
  ```c
  {
  .ident = "Lenovo Yoga 6 13ALC6",
  .driver_data = &quirk_s2idle_bug,
  .matches = {
  DMI_MATCH(DMI_BOARD_VENDOR, "LENOVO"),
  DMI_MATCH(DMI_PRODUCT_NAME, "82ND"),
  }
  },
  ```

3. **Follows established pattern**: The fix uses the exact same
   mechanism (`quirk_s2idle_bug`) that's already applied to 20+ other
   Lenovo laptops in the same file. The workaround manipulates a scratch
   register (FCH_PM_SCRATCH) to skip a problematic SMI handler during
   suspend-to-idle resume, as documented in the comment at lines
   241-248.

4. **No architectural changes**: This is purely a device-specific quirk
   addition to an existing quirk framework. No new functionality is
   introduced, no APIs are changed, and no kernel subsystem architecture
   is modified.

5. **Low regression risk**: The change only affects systems that match
   the specific DMI strings (LENOVO board vendor + 82ND product name).
   It cannot affect any other hardware.

6. **Tested by reporter**: The commit message indicates "Tested-by: Adam
   Berglund" who was also the reporter of the issue, confirming the fix
   works on the affected hardware.

7. **Follows stable tree rules**: This is exactly the type of commit
   that stable trees want:
   - Fixes a real bug (long resume times)
   - Minimal change (8 lines)
   - Hardware-specific fix with no broader impact
   - Already tested on affected hardware

The issue being fixed is documented at
https://gitlab.freedesktop.org/drm/amd/-/issues/4434, and the workaround
applies the same proven fix that's been working for numerous other
Lenovo models with similar BIOS issues related to suspend-to-idle resume
performance when IOMMU is enabled for NVMe devices.

 drivers/platform/x86/amd/pmc/pmc-quirks.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/platform/x86/amd/pmc/pmc-quirks.c b/drivers/platform/x86/amd/pmc/pmc-quirks.c
index 131f10b68308..ded4c84f5ed1 100644
--- a/drivers/platform/x86/amd/pmc/pmc-quirks.c
+++ b/drivers/platform/x86/amd/pmc/pmc-quirks.c
@@ -190,6 +190,15 @@ static const struct dmi_system_id fwbug_list[] = {
 			DMI_MATCH(DMI_PRODUCT_NAME, "82XQ"),
 		}
 	},
+	/* https://gitlab.freedesktop.org/drm/amd/-/issues/4434 */
+	{
+		.ident = "Lenovo Yoga 6 13ALC6",
+		.driver_data = &quirk_s2idle_bug,
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "82ND"),
+		}
+	},
 	/* https://gitlab.freedesktop.org/drm/amd/-/issues/2684 */
 	{
 		.ident = "HP Laptop 15s-eq2xxx",
-- 
2.39.5