[PATCH 3/4] platform/x86/amd/pmc: Do not fail probe when STB init fails

[Mario Limonciello]

STB (Spill to DRAM) is an optional debugging facility that is only
enabled through the enable_stb module parameter.  On some platforms the
SMU refuses the S2D setup outright, and on long-running systems the large
telemetry region can fail to ioremap.  In either case amd_stb_s2d_init()
returns an error and, because probe treated that as fatal, the entire
PMC driver failed to load - silently disabling s0i3 support even though
STB is only a debug aid.

Downgrade the failure to a warning and continue probing so that s0i3
support via the LPS0 handler no longer depends on an optional debug
feature.

Since probe no longer aborts on this path, the LPS0 and debugfs
unwinding added by the earlier fix in this series becomes unreachable
and is removed.

Assisted-by: Claude:opus
Reported-by: Francis De Brabandere <francisdb@xxxxxxxxx>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221759
Tested-by: Francis De Brabandere <francisdb@xxxxxxxxx>
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
 drivers/platform/x86/amd/pmc/pmc.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/amd/pmc/pmc.c b/drivers/platform/x86/amd/pmc/pmc.c
index 630a664bdd2f4..5b6c90abd4e5f 100644
--- a/drivers/platform/x86/amd/pmc/pmc.c
+++ b/drivers/platform/x86/amd/pmc/pmc.c
@@ -917,19 +917,24 @@ static int amd_pmc_probe(struct platform_device *pdev)
 	}
 
 	amd_pmc_dbgfs_register(dev);
+
+	/*
+	 * STB is an optional debugging facility, only enabled via the
+	 * enable_stb module parameter.  A failure to initialize it (e.g. the
+	 * SMU refusing the request, or the telemetry region failing to map)
+	 * must not prevent the rest of the driver - most importantly the s0i3
+	 * LPS0 handler - from working, so treat it as non-fatal.
+	 */
 	err = amd_stb_s2d_init(dev);
 	if (err)
-		goto err_dbgfs_unregister;
+		dev_warn(dev->dev, "STB initialization failed (%d), continuing without STB support\n",
+			 err);
 
 	if (IS_ENABLED(CONFIG_AMD_MP2_STB))
 		amd_mp2_stb_init(dev);
 	pm_report_max_hw_sleep(U64_MAX);
 	return 0;
 
-err_dbgfs_unregister:
-	amd_pmc_dbgfs_unregister(dev);
-	if (IS_ENABLED(CONFIG_SUSPEND))
-		acpi_unregister_lps0_dev(&amd_pmc_s2idle_dev_ops);
 err_pci_dev_put:
 	pci_dev_put(rdev);
 	return err;
-- 
2.43.0