[PATCH AUTOSEL 6.18-6.12] ata: libata-core: Disable LPM on ST2000DM008-2FR102

[PATCH AUTOSEL 6.18-6.12] ata: libata-core: Disable LPM on ST2000DM008-2FR102

[Sasha Levin]

From: Niklas Cassel <cassel@kernel.org>

[ Upstream commit ba624ba88d9f5c3e2ace9bb6697dbeb05b2dbc44 ]

According to a user report, the ST2000DM008-2FR102 has problems with LPM.

Reported-by: Emerson Pinter <e@pinter.dev>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220693
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

## Analysis of Commit: Disable LPM on ST2000DM008-2FR102

### 1. COMMIT MESSAGE ANALYSIS

The commit message is clear and provides essential information:
- **Purpose:** Disabling Link Power Management (LPM) for a specific
  Seagate hard drive model
- **Evidence of real issue:** Has `Reported-by:` tag and references
  kernel bugzilla #220693
- **Proper sign-offs:** Signed by both the patch author (Niklas Cassel)
  and the libata maintainer (Damien Le Moal)

### 2. CODE CHANGE ANALYSIS

The change adds exactly 3 lines to the `__ata_dev_quirks[]` array in
`drivers/ata/libata-core.c`:

```c
/* Seagate disks with LPM issues */
{ "ST2000DM008-2FR102", NULL,           ATA_QUIRK_NOLPM },
```

This follows the exact same pattern as existing quirks in the table.
Looking at the context, there's already another Seagate drive with
`ATA_QUIRK_NOLPM`:
```c
{ "ST1000LM024 HN-M101MBB", NULL,       ATA_QUIRK_BROKEN_FPDMA_AA |
                                        ATA_QUIRK_NOLPM },
```

The mechanism is well-understood: when this specific drive model is
detected, LPM is disabled to avoid the hardware-specific issues it
causes.

### 3. CLASSIFICATION

This is a **hardware quirk/workaround** - one of the explicit exceptions
allowed in stable:
- It's adding a device-specific workaround to an existing quirk table
- Identical pattern to dozens of other quirks already in the table
- Fixes real-world hardware issues even though it "adds code"

### 4. SCOPE AND RISK ASSESSMENT

| Metric | Assessment |
|--------|------------|
| Lines changed | 3 (minimal) |
| Files touched | 1 |
| Complexity | Trivial - data table addition |
| Risk to other users | Zero - only affects this specific drive model |
| Regression potential | None - well-established mechanism |

The risk is essentially zero. This is a data-only change to a static
array. The quirk mechanism has been stable for many years and is used
extensively for similar hardware workarounds.

### 5. USER IMPACT

- **Affected users:** Owners of ST2000DM008-2FR102 (2TB Seagate
  Barracuda) - a popular consumer HDD
- **Without the fix:** LPM-related issues typically cause drive
  disconnects, I/O errors, or system hangs
- **Severity:** Medium to High - LPM issues can cause data corruption or
  loss in severe cases
- **Real bug evidence:** Bugzilla report indicates actual users hitting
  this problem

### 6. STABILITY INDICATORS

- Approved by libata maintainer (Damien Le Moal)
- Proper bug tracking with Closes: tag
- Reported-by indicates real user testing/reporting

### 7. DEPENDENCY CHECK

- **Dependencies:** None - standalone quirk addition
- **Code exists in stable:** Yes - the quirk table and `ATA_QUIRK_NOLPM`
  exist in all maintained stable kernels
- **Backport complexity:** Trivial - should apply cleanly to any stable
  kernel

### FINAL ASSESSMENT

This commit is a textbook example of what SHOULD be backported to
stable:

**Meets all stable criteria:**
1. ✅ Obviously correct - identical pattern to existing quirks
2. ✅ Fixes a real bug - LPM issues reported by users
3. ✅ Small and contained - 3 lines, 1 file
4. ✅ No new features - just a hardware workaround
5. ✅ Falls into "quirks/workarounds" exception category

**Risk vs Benefit:**
- **Risk:** Essentially zero - only affects one specific drive model,
  cannot break anything else
- **Benefit:** Fixes LPM-related issues (drive disconnects, errors,
  potential data corruption) for users of this popular Seagate drive

This is exactly the type of low-risk, high-value hardware workaround
that stable trees are designed to include.

**YES**

 drivers/ata/libata-core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index f48fb63d7e85..1216b4f2eb90 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4132,6 +4132,9 @@ static const struct ata_dev_quirks_entry __ata_dev_quirks[] = {
 	{ "ST3320[68]13AS",	"SD1[5-9]",	ATA_QUIRK_NONCQ |
 						ATA_QUIRK_FIRMWARE_WARN },
 
+	/* Seagate disks with LPM issues */
+	{ "ST2000DM008-2FR102",	NULL,		ATA_QUIRK_NOLPM },
+
 	/* drives which fail FPDMA_AA activation (some may freeze afterwards)
 	   the ST disks also have LPM issues */
 	{ "ST1000LM024 HN-M101MBB", NULL,	ATA_QUIRK_BROKEN_FPDMA_AA |
-- 
2.51.0