thunderbolt: debugfs: Fix margin debugfs node creation condition

From: Aapo Vienamo <[email protected]>

The margin debugfs node controls the "Enable Margin Test" field of the lane margining operations. This field selects between either low or high voltage margin values for voltage margin test or left or right timing margin values for timing margin test.

According to the USB4 specification, whether or not the "Enable Margin Test" control applies, depends on the values of the "Independent High/Low Voltage Margin" or "Independent Left/Right Timing Margin" capability fields for voltage and timing margin tests respectively. The pre-existing condition enabled the debugfs node also in the case where both low/high or left/right margins are returned, which is incorrect. This change only enables the debugfs node in question, if the specific required capability values are met.

---
 drivers/thunderbolt/debugfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

index 193e9dfc983b..70b52aac3d97 100644
@@ -943,8 +943,9 @@ static void margining_port_init(struct tb_port *port)
 	debugfs_create_file("run", 0600, dir, port, &margining_run_fops);
 	debugfs_create_file("results", 0600, dir, port, &margining_results_fops);
 	debugfs_create_file("test", 0600, dir, port, &margining_test_fops);
-	if (independent_voltage_margins(usb4) ||
-	    (supports_time(usb4) && independent_time_margins(usb4)))
+	if (independent_voltage_margins(usb4) == USB4_MARGIN_CAP_0_VOLTAGE_HL ||
+	    (supports_time(usb4) &&
+	     independent_time_margins(usb4) == USB4_MARGIN_CAP_1_TIME_LR))
 		debugfs_create_file("margin", 0600, dir, port, &margining_margin_fops);
 }
 

2.43.0

Applied to thunderbolt.git/fixes.