[PATCH AUTOSEL 6.19-6.18] EDAC/igen6: Add two Intel Amston Lake SoCs support

[Sasha Levin <sashal@kernel.org>]

From: Qiuxu Zhuo <qiuxu.zhuo@intel.com>

[ Upstream commit 41ca2155d62b0b0d217f59e1bce18362d0c2446f ]

Intel Amston Lake SoCs with IBECC (In-Band ECC) capability share the same
IBECC registers as Alder Lake-N SoCs. Add two new compute die IDs for
Amston Lake SoC products to enable EDAC support.

Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Tested-by: Jianfeng Gao <jianfeng.gao@intel.com>
Link: https://patch.msgid.link/20251124065457.3630949-2-qiuxu.zhuo@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

Now I have all the information needed for a complete analysis. Here is
my detailed assessment:

---

## Detailed Analysis: EDAC/igen6: Add two Intel Amston Lake SoCs support

### 1. Commit Message Analysis

The commit adds two new PCI compute die IDs (`DID_ASL_SKU2 = 0x4646`,
`DID_ASL_SKU3 = 0x4652`) for Intel Amston Lake SoC products to the
`igen6_edac` driver. The commit message explicitly states these SoCs
share the same IBECC registers as Alder Lake-N, meaning they reuse the
existing `adl_n_cfg` configuration structure.

- **Author**: Qiuxu Zhuo (Intel) - the primary maintainer and original
  author of this driver
- **Signed-off-by**: Tony Luck (Intel RAS maintainer) - trusted
  subsystem maintainer
- **Tested-by**: Jianfeng Gao (Intel) - hardware tested on actual Amston
  Lake devices

### 2. Code Change Analysis

The diff is minimal - exactly **4 lines added** across a single file:

1. **Two `#define` additions** (lines after existing `DID_ASL_SKU1`):
   - `#define DID_ASL_SKU2 0x4646`
   - `#define DID_ASL_SKU3 0x4652`

2. **Two PCI device table entries** (in `igen6_pci_tbl[]`):
   - `{ PCI_VDEVICE(INTEL, DID_ASL_SKU2), (kernel_ulong_t)&adl_n_cfg }`
   - `{ PCI_VDEVICE(INTEL, DID_ASL_SKU3), (kernel_ulong_t)&adl_n_cfg }`

Both new entries use the already-existing `adl_n_cfg` configuration,
which has been in the kernel since v6.8 (commit `c4a5398991fd2`). No new
code paths, no new functions, no behavioral changes. This is a pure PCI
device ID addition.

### 3. Classification: New Device IDs (Explicitly Allowed Exception)

This is a textbook **new device ID addition** to an existing driver. The
stable kernel rules documentation explicitly allows this:

> "Adding PCI IDs, USB IDs, ACPI IDs, etc. to existing drivers - These
are trivial one-line additions that enable hardware support"

The pattern is identical to many prior device ID additions to this
driver:
- Arizona Beach (`b804d7c59aea0`) - single PCI ID using `adl_n_cfg`
- Alder Lake-N extra SKU (`65c441ec58224`) - single PCI ID using
  `adl_n_cfg`
- Arrow Lake-U/H (`88150cd9501b9`) - PCI IDs using `mtl_p_cfg`

### 4. Scope and Risk Assessment

- **Lines changed**: 4 added, 0 deleted
- **Files touched**: 1 (`drivers/edac/igen6_edac.c`)
- **Complexity**: Near-zero - just PCI ID defines and table entries
- **Risk of regression**: Effectively zero. The new PCI IDs will only
  match hardware that has those specific device IDs. If no such hardware
  is present, the entries are completely inert. If the hardware IS
  present, it uses the well-tested `adl_n_cfg` path that Alder Lake-N,
  Arizona Beach, and Amston Lake SKU1 all use.

### 5. User Impact

Intel Amston Lake SoCs are described as "tailored for edge computing
needs" in the original Amston Lake commit. EDAC (Error Detection and
Correction) is critical for:
- **Edge computing and embedded systems** - where these SoCs are
  deployed
- **Reliability-critical environments** - where memory error detection
  prevents silent data corruption
- **Enterprise/industrial applications** - Amston Lake targets this
  market segment

Without these device IDs, users with Amston Lake SKU2/SKU3 hardware get
**no IBECC EDAC support** - meaning memory errors go undetected, which
can lead to silent data corruption.

### 6. Stability Indicators

- Written by the driver's original author (Qiuxu Zhuo at Intel)
- Signed-off by the RAS subsystem maintainer (Tony Luck)
- Hardware-tested by Intel engineer (Jianfeng Gao)
- The same `adl_n_cfg` config is already used by 12+ Alder Lake-N SKUs,
  Arizona Beach, and ASL_SKU1 - extremely well-tested code path

### 7. Dependency Check

This commit depends on commit `099d2db3625b3` ("EDAC/igen6: Add Intel
Amston Lake SoCs support") which introduced `DID_ASL_SKU1` and the
Amston Lake comment section. That commit landed in v6.16-rc1. Both
commits would need to be backported together to stable trees that have
`adl_n_cfg` (v6.8+). This is straightforward - both are trivial device
ID additions.

The `adl_n_cfg` configuration exists since v6.8 (commit
`c4a5398991fd2`), so active stable trees 6.8.y, 6.12.y would have the
necessary infrastructure. For 6.6.y, the `adl_n_cfg` is also present
since it was added in v6.8-rc1 which branched after 6.6 - actually let
me verify:

The `adl_n_cfg` was introduced by `c4a5398991fd2` which is tagged at
`v6.8-rc1~209^2~8`. This means it's in v6.8+. Active stable trees like
6.12.y and 6.6.y need to be checked individually, but 6.6.y would NOT
have `adl_n_cfg` since it predates v6.8. Stable trees 6.8+ would have
it.

### Summary

| Criterion | Assessment |
|---|---|
| Fixes real issue? | Yes - enables EDAC on Amston Lake SKU2/SKU3
hardware |
| Obviously correct? | Yes - trivial PCI ID addition |
| Small and contained? | Yes - 4 lines, 1 file |
| New features? | No - enables existing functionality on new hardware |
| Risk? | Near-zero |
| Tested? | Yes (Tested-by tag from Intel) |
| Category | New Device IDs - explicitly allowed in stable |

This commit is a clear-cut example of the "new device ID" exception to
stable kernel rules. It enables EDAC support for real Intel hardware
(Amston Lake edge computing SoCs) with zero risk of regression. The
change is trivial, authored and tested by Intel engineers, and follows
the exact same pattern as numerous prior device ID additions to this
driver.

**YES**

 drivers/edac/igen6_edac.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/edac/igen6_edac.c b/drivers/edac/igen6_edac.c
index 839b6dd3629e9..f2c9270c1893c 100644
--- a/drivers/edac/igen6_edac.c
+++ b/drivers/edac/igen6_edac.c
@@ -246,6 +246,8 @@ static struct work_struct ecclog_work;
 
 /* Compute did IDs for Amston Lake with IBECC */
 #define DID_ASL_SKU1	0x464a
+#define DID_ASL_SKU2	0x4646
+#define DID_ASL_SKU3	0x4652
 
 /* Compute die IDs for Raptor Lake-P with IBECC */
 #define DID_RPL_P_SKU1	0xa706
@@ -628,6 +630,8 @@ static struct pci_device_id igen6_pci_tbl[] = {
 	{ PCI_VDEVICE(INTEL, DID_ADL_N_SKU12), (kernel_ulong_t)&adl_n_cfg },
 	{ PCI_VDEVICE(INTEL, DID_AZB_SKU1), (kernel_ulong_t)&adl_n_cfg },
 	{ PCI_VDEVICE(INTEL, DID_ASL_SKU1), (kernel_ulong_t)&adl_n_cfg },
+	{ PCI_VDEVICE(INTEL, DID_ASL_SKU2), (kernel_ulong_t)&adl_n_cfg },
+	{ PCI_VDEVICE(INTEL, DID_ASL_SKU3), (kernel_ulong_t)&adl_n_cfg },
 	{ PCI_VDEVICE(INTEL, DID_RPL_P_SKU1), (kernel_ulong_t)&rpl_p_cfg },
 	{ PCI_VDEVICE(INTEL, DID_RPL_P_SKU2), (kernel_ulong_t)&rpl_p_cfg },
 	{ PCI_VDEVICE(INTEL, DID_RPL_P_SKU3), (kernel_ulong_t)&rpl_p_cfg },
-- 
2.51.0