drm/amdgpu: add amdgpu.ptl module parameter for PTL control

Add a new kernel module parameter 'amdgpu.ptl' to allow
users to enable or disable PTL feature at driver loading time.

Parameter values:
  *) 0 or -1: disable PTL (default)
  *) 1: enable PTL
  *) 2: permanently disable PTL

Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Reviewed-by: Yifan Zhang <yifan1.zhang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -267,6 +267,7 @@ extern int amdgpu_rebar;
 
 extern int amdgpu_wbrf;
 extern int amdgpu_user_queue;
+extern int amdgpu_ptl;
 
 extern uint amdgpu_hdmi_hpd_debounce_delay_ms;
 

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

@@ -246,6 +246,7 @@ int amdgpu_umsch_mm_fwlog;
 int amdgpu_rebar = -1; /* auto */
 int amdgpu_user_queue = -1;
 uint amdgpu_hdmi_hpd_debounce_delay_ms;
+int amdgpu_ptl = -1; /* auto */
 
 DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
 			"DRM_UT_CORE",
@@ -1112,6 +1113,18 @@ module_param_named(user_queue, amdgpu_user_queue, int, 0444);
 MODULE_PARM_DESC(hdmi_hpd_debounce_delay_ms, "HDMI HPD disconnect debounce delay in milliseconds (0 to disable (by default), 1500 is common)");
 module_param_named(hdmi_hpd_debounce_delay_ms, amdgpu_hdmi_hpd_debounce_delay_ms, uint, 0644);
 
+/**
+ * DOC: ptl (int)
+ * Enable PTL feature at boot time. Possible values:
+ *
+ * - -1 = auto (ASIC specific default)
+ * -  0 = disable PTL (default)
+ * -  1 = enable PTL
+ * -  2 = permanently disable PTL (cannot be re-enabled at runtime)
+ */
+MODULE_PARM_DESC(ptl, "Enable PTL (-1 = auto, 0 = disable (default), 1 = enable, 2 = permanently disable)");
+module_param_named(ptl, amdgpu_ptl, int, 0444);
+
 /* These devices are not supported by amdgpu.
  * They are supported by the mach64, r128, radeon drivers
  */

drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c

@@ -1300,6 +1300,9 @@ int amdgpu_ptl_perf_monitor_ctrl(struct amdgpu_device *adev, u32 req_code,
 	psp = &adev->psp;
 	ptl = &psp->ptl;
 
+	if (ptl->permanently_disabled && *ptl_state == 1)
+		return 0;
+
 	if (amdgpu_ip_version(adev, GC_HWIP, 0) != IP_VERSION(9, 4, 4) ||
 			psp->sos.fw_version < 0x0036081a)
 		return -EOPNOTSUPP;
@@ -1386,6 +1389,12 @@ static ssize_t ptl_enable_store(struct device *dev,
 		return -EINVAL;
 	}
 
+	/* Block enable when permanently disabled */
+	if (ptl->permanently_disabled) {
+		mutex_unlock(&ptl->mutex);
+		return -EPERM;
+	}
+
 	fmt1 = ptl->fmt1;
 	fmt2 = ptl->fmt2;
 	ptl_state = enable ? 1 : 0;
@@ -1417,6 +1426,9 @@ static ssize_t ptl_enable_show(struct device *dev, struct device_attribute *attr
 	struct amdgpu_device *adev = drm_to_adev(ddev);
 	struct amdgpu_ptl *ptl = &adev->psp.ptl;
 
+	if (ptl->permanently_disabled)
+		return sysfs_emit(buf, "permanently disabled\n");
+
 	return sysfs_emit(buf, "%s\n", ptl->enabled ? "enabled" : "disabled");
 }
 

drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c

@@ -2405,6 +2405,32 @@ static int gfx_v9_4_3_perf_monitor_ptl_init(struct amdgpu_device *adev, bool ena
 	return 0;
 }
 
+static int gfx_v9_4_3_ptl_hw_init(struct amdgpu_device *adev)
+{
+	struct amdgpu_ptl *ptl = &adev->psp.ptl;
+	bool enable;
+
+	switch (amdgpu_ptl) {
+	case 1:
+		enable = true;
+		break;
+	case 2:
+		/* Permanently disabled - cannot be re-enabled */
+		enable = false;
+		ptl->permanently_disabled = true;
+		break;
+	case -1:
+	case 0:
+	default:
+		enable = false;
+		break;
+	}
+
+	gfx_v9_4_3_perf_monitor_ptl_init(adev, enable ? 1 : 0);
+
+	return 0;
+}
+
 static int gfx_v9_4_3_hw_fini(struct amdgpu_ip_block *ip_block)
 {
 	struct amdgpu_device *adev = ip_block->adev;
@@ -2587,7 +2613,7 @@ static int gfx_v9_4_3_late_init(struct amdgpu_ip_block *ip_block)
 	    adev->gfx.ras->enable_watchdog_timer)
 		adev->gfx.ras->enable_watchdog_timer(adev);
 
-	gfx_v9_4_3_perf_monitor_ptl_init(adev, true);
+	gfx_v9_4_3_ptl_hw_init(adev);
 
 	return 0;
 }

drivers/gpu/drm/amd/include/amdgpu_ptl.h

@@ -44,6 +44,7 @@ struct amdgpu_ptl {
 	enum amdgpu_ptl_fmt		fmt2;
 	bool				enabled;
 	bool				hw_supported;
+	bool				permanently_disabled;
 	/* PTL disable reference counting */
 	atomic_t			disable_ref;
 	struct mutex			mutex;