From 891a5bb04a602efa31a58c2d66b043c943445f64 Mon Sep 17 00:00:00 2001
From: Alex Deucher <alexander.deucher@amd.com>
Date: Thu, 21 Jan 2021 16:39:59 -0500
Subject: drm/amdgpu: add a mutex for the smu11 i2c bus (v2)
Git-commit: 6963d6c176fe36c775996cfd6886d4c4234ccd9e
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

So we lock software as well as hardware access to the bus.

v2: fix mutex handling.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/amd/amdgpu/smu_v11_0_i2c.c | 19 +++++++++----------
 drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h    |  1 +
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/smu_v11_0_i2c.c b/drivers/gpu/drm/amd/amdgpu/smu_v11_0_i2c.c
index 5c7d769aee3f..1d8f6d5180e0 100644
--- a/drivers/gpu/drm/amd/amdgpu/smu_v11_0_i2c.c
+++ b/drivers/gpu/drm/amd/amdgpu/smu_v11_0_i2c.c
@@ -584,12 +584,11 @@ static void lock_bus(struct i2c_adapter *i2c, unsigned int flags)
 {
 	struct amdgpu_device *adev = to_amdgpu_device(i2c);
 
-	if (!smu_v11_0_i2c_bus_lock(i2c)) {
+	mutex_lock(&adev->pm.smu_i2c_mutex);
+	if (!smu_v11_0_i2c_bus_lock(i2c))
 		DRM_ERROR("Failed to lock the bus from SMU");
-		return;
-	}
-
-	adev->pm.bus_locked = true;
+	else
+		adev->pm.bus_locked = true;
 }
 
 static int trylock_bus(struct i2c_adapter *i2c, unsigned int flags)
@@ -602,12 +601,11 @@ static void unlock_bus(struct i2c_adapter *i2c, unsigned int flags)
 {
 	struct amdgpu_device *adev = to_amdgpu_device(i2c);
 
-	if (!smu_v11_0_i2c_bus_unlock(i2c)) {
+	if (!smu_v11_0_i2c_bus_unlock(i2c))
 		DRM_ERROR("Failed to unlock the bus from SMU");
-		return;
-	}
-
-	adev->pm.bus_locked = false;
+	else
+		adev->pm.bus_locked = false;
+	mutex_unlock(&adev->pm.smu_i2c_mutex);
 }
 
 static const struct i2c_lock_operations smu_v11_0_i2c_i2c_lock_ops = {
@@ -665,6 +663,7 @@ int smu_v11_0_i2c_control_init(struct i2c_adapter *control)
 	struct amdgpu_device *adev = to_amdgpu_device(control);
 	int res;
 
+	mutex_init(&adev->pm.smu_i2c_mutex);
 	control->owner = THIS_MODULE;
 	control->class = I2C_CLASS_SPD;
 	control->dev.parent = &adev->pdev->dev;
diff --git a/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h b/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
index f6e0e7d8a007..d03e6fa2bf1a 100644
--- a/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
+++ b/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
@@ -450,6 +450,7 @@ struct amdgpu_pm {
 
 	/* Used for I2C access to various EEPROMs on relevant ASICs */
 	struct i2c_adapter smu_i2c;
+	struct mutex		smu_i2c_mutex;
 	struct list_head	pm_attr_list;
 };
 
-- 
2.38.1