[PATCH] thunderbolt: debugfs: Fix margin debugfs node creation condition

[PATCH] thunderbolt: debugfs: Fix margin debugfs node creation condition

[Mika Westerberg]

From: Aapo Vienamo <aapo.vienamo@linux.intel.com>

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.

Signed-off-by: Aapo Vienamo <aapo.vienamo@linux.intel.com>
Fixes: d0f1e0c2a699 ("thunderbolt: Add support for receiver lane margining")
Cc: stable@vger.kernel.org
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/thunderbolt/debugfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/thunderbolt/debugfs.c b/drivers/thunderbolt/debugfs.c
index 193e9dfc983b..70b52aac3d97 100644
--- a/drivers/thunderbolt/debugfs.c
+++ b/drivers/thunderbolt/debugfs.c
@@ -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

Re: [PATCH] thunderbolt: debugfs: Fix margin debugfs node creation condition

[Mika Westerberg]

On Wed, May 29, 2024 at 03:36:47PM +0300, Mika Westerberg wrote:
> From: Aapo Vienamo <aapo.vienamo@linux.intel.com>
> 
> 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.
> 
> Signed-off-by: Aapo Vienamo <aapo.vienamo@linux.intel.com>
> Fixes: d0f1e0c2a699 ("thunderbolt: Add support for receiver lane margining")
> Cc: stable@vger.kernel.org
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Applied to thunderbolt.git/fixes.