[PATCH] thunderbolt: Add only on-board retimers when !CONFIG_USB4_DEBUGFS_MARGINING

[PATCH] thunderbolt: Add only on-board retimers when !CONFIG_USB4_DEBUGFS_MARGINING

[Mika Westerberg]

Normally there is no need to enumerate retimers on the other side of the
cable. This is only needed in special cases where user wants to run
receiver lane margining against the downstream facing port of a retimer.
Furthermore this might confuse the userspace tools such as fwupd because
it cannot read the information it expects from these retimers.

Fix this by changing the retimer enumeration code to add only on-board
retimers when CONFIG_USB4_DEBUGFS_MARGINING is not enabled.

Reported-by: AceLan Kao <acelan.kao@canonical.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219420
Cc: stable@vger.kernel.org
Fixes: ff6ab055e070 ("thunderbolt: Add receiver lane margining support for retimers")
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
Hi AceLan,

I changed the patch slightly. I wonder if you could try it again?

Thanks!

 drivers/thunderbolt/retimer.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/thunderbolt/retimer.c b/drivers/thunderbolt/retimer.c
index 7db9869a9f3f..89d2919d0193 100644
--- a/drivers/thunderbolt/retimer.c
+++ b/drivers/thunderbolt/retimer.c
@@ -532,6 +532,8 @@ int tb_retimer_scan(struct tb_port *port, bool add)
 	}
 
 	ret = 0;
+	if (!IS_ENABLED(CONFIG_USB4_DEBUGFS_MARGINING))
+		max = min(last_idx, max);
 
 	/* Add retimers if they do not exist already */
 	for (i = 1; i <= max; i++) {
-- 
2.45.2

Re: [PATCH] thunderbolt: Add only on-board retimers when !CONFIG_USB4_DEBUGFS_MARGINING

[Chia-Lin Kao (AceLan)]

On Mon, Oct 28, 2024 at 12:51:21PM +0200, Mika Westerberg wrote:
> Normally there is no need to enumerate retimers on the other side of the
> cable. This is only needed in special cases where user wants to run
> receiver lane margining against the downstream facing port of a retimer.
> Furthermore this might confuse the userspace tools such as fwupd because
> it cannot read the information it expects from these retimers.
> 
> Fix this by changing the retimer enumeration code to add only on-board
> retimers when CONFIG_USB4_DEBUGFS_MARGINING is not enabled.
> 
> Reported-by: AceLan Kao <acelan.kao@canonical.com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219420
> Cc: stable@vger.kernel.org
> Fixes: ff6ab055e070 ("thunderbolt: Add receiver lane margining support for retimers")
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
> Hi AceLan,
> 
> I changed the patch slightly. I wonder if you could try it again?
Yes, this revision also fixes the issue.
Thanks.

Tested-by: AceLan Kao <acelan.kao@canonical.com>

> 
> Thanks!
> 
>  drivers/thunderbolt/retimer.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/thunderbolt/retimer.c b/drivers/thunderbolt/retimer.c
> index 7db9869a9f3f..89d2919d0193 100644
> --- a/drivers/thunderbolt/retimer.c
> +++ b/drivers/thunderbolt/retimer.c
> @@ -532,6 +532,8 @@ int tb_retimer_scan(struct tb_port *port, bool add)
>  	}
>  
>  	ret = 0;
> +	if (!IS_ENABLED(CONFIG_USB4_DEBUGFS_MARGINING))
> +		max = min(last_idx, max);
>  
>  	/* Add retimers if they do not exist already */
>  	for (i = 1; i <= max; i++) {
> -- 
> 2.45.2
> 

Re: [PATCH] thunderbolt: Add only on-board retimers when !CONFIG_USB4_DEBUGFS_MARGINING

[Mika Westerberg]

On Mon, Oct 28, 2024 at 07:12:51PM +0800, Chia-Lin Kao (AceLan) wrote:
> On Mon, Oct 28, 2024 at 12:51:21PM +0200, Mika Westerberg wrote:
> > Normally there is no need to enumerate retimers on the other side of the
> > cable. This is only needed in special cases where user wants to run
> > receiver lane margining against the downstream facing port of a retimer.
> > Furthermore this might confuse the userspace tools such as fwupd because
> > it cannot read the information it expects from these retimers.
> > 
> > Fix this by changing the retimer enumeration code to add only on-board
> > retimers when CONFIG_USB4_DEBUGFS_MARGINING is not enabled.
> > 
> > Reported-by: AceLan Kao <acelan.kao@canonical.com>
> > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219420
> > Cc: stable@vger.kernel.org
> > Fixes: ff6ab055e070 ("thunderbolt: Add receiver lane margining support for retimers")
> > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > ---
> > Hi AceLan,
> > 
> > I changed the patch slightly. I wonder if you could try it again?
> Yes, this revision also fixes the issue.
> Thanks.
> 
> Tested-by: AceLan Kao <acelan.kao@canonical.com>

Thanks for testing!

Applied to thunderbolt.git/fixes.