[PATCH 6.1.y 2/2] platform/x86/amd/pmc: Restore msg_port on amd_stb_s2d_init() error paths

[Sasha Levin <sashal@kernel.org>]

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

[ Upstream commit 9cef693bce96bb4c6952f48d855284cf7fa4f367 ]

dev->msg_port is switched to MSG_PORT_S2D before issuing the S2D SMU
commands but is only restored to MSG_PORT_PMC on the success path.  The
early "return -EIO" and "return -ENOMEM" leave the port stuck on
MSG_PORT_S2D, so all subsequent SMU communication - including the s2idle
prepare/restore handlers - is directed at the wrong mailbox.

Consolidate the exit path through a single label so the message port is
always restored.

Fixes: 3d7d407dfb05 ("platform/x86: amd-pmc: Add support for AMD Spill to DRAM STB feature")
Cc: stable@vger.kernel.org
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/20260721181756.143084-2-mario.limonciello@amd.com
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>
---
 drivers/platform/x86/amd/pmc/mp1_stb.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/x86/amd/pmc/mp1_stb.c b/drivers/platform/x86/amd/pmc/mp1_stb.c
index c5de2b6208c3b..484d9d9d6df2c 100644
--- a/drivers/platform/x86/amd/pmc/mp1_stb.c
+++ b/drivers/platform/x86/amd/pmc/mp1_stb.c
@@ -31,7 +31,7 @@ int amd_pmc_s2d_init(struct amd_pmc_dev *dev)
 	u32 phys_addr_low, phys_addr_hi;
 	u64 stb_phys_addr;
 	u32 size = 0;
-	int ret;
+	int ret = 0;
 
 	if (!enable_stb)
 		return 0;
@@ -42,8 +42,10 @@ int amd_pmc_s2d_init(struct amd_pmc_dev *dev)
 	dev->msg_port = MSG_PORT_S2D;
 
 	amd_pmc_send_cmd(dev, S2D_TELEMETRY_SIZE, &size, dev->stb_arg.s2d_msg_id, true);
-	if (size != S2D_TELEMETRY_BYTES_MAX)
-		return -EIO;
+	if (size != S2D_TELEMETRY_BYTES_MAX) {
+		ret = -EIO;
+		goto out;
+	}
 
 	/* Get DRAM size */
 	ret = amd_pmc_send_cmd(dev, S2D_DRAM_SIZE, &dev->dram_size, dev->stb_arg.s2d_msg_id, true);
@@ -62,12 +64,16 @@ int amd_pmc_s2d_init(struct amd_pmc_dev *dev)
 
 	stb_phys_addr = ((u64)phys_addr_hi << 32 | phys_addr_low);
 
-	/* Clear msg_port for other SMU operation */
-	dev->msg_port = MSG_PORT_PMC;
-
 	dev->stb_virt_addr = devm_ioremap(dev->dev, stb_phys_addr, dev->dram_size);
-	if (!dev->stb_virt_addr)
-		return -ENOMEM;
+	if (!dev->stb_virt_addr) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = 0;
 
-	return 0;
+out:
+	/* Restore the default message port for subsequent SMU operations */
+	dev->msg_port = MSG_PORT_PMC;
+	return ret;
 }
-- 
2.53.0