[PATCH v2 6/6] platform/x86/amd/pmc: Do not fail probe when STB init fails

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.

Reported-by: Francis De Brabandere <[email protected]>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221759
Tested-by: Francis De Brabandere <[email protected]>
Signed-off-by: Mario Limonciello <[email protected]>
---
 drivers/platform/x86/amd/pmc/pmc.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/platform/x86/amd/pmc/pmc.c b/drivers/platform/x86/amd/pmc/pmc.c
index 630a664bdd2f4..0e013402c1c65 100644
--- a/drivers/platform/x86/amd/pmc/pmc.c
+++ b/drivers/platform/x86/amd/pmc/pmc.c
@@ -917,19 +917,22 @@ static int amd_pmc_probe(struct platform_device *pdev)
 	}
 
 	amd_pmc_dbgfs_register(dev);
+
+	/*
+	 * STB is an optional debug facility (enable_stb); a failure to set it
+	 * up must not stop 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