[PATCH 5.4.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[PATCH 5.4.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

This reverts commit 2402adce8da4e7396b63b5ffa71e1fa16e5fe5c4.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 4eabef5b86d0..ffc68d305afe 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -280,7 +280,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 	 * We just have to do it before any DPCD access and hope that the
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
-	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_LANE0_1_STATUS, buffer,
+	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer,
 				 1);
 	if (ret != 1)
 		goto out;
-- 
2.49.1

[PATCH 5.10.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

This reverts commit 89d17a2d89a83c5b7643ca934651a3f9229e4734.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index ba8ab1dc4912..6ba16db77500 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -299,7 +299,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
 	if (!aux->is_remote) {
-		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_LANE0_1_STATUS,
+		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV,
 					 buffer, 1);
 		if (ret != 1)
 			goto out;
-- 
2.49.1

Patch "Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"" has been added to the 5.10-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     revert-drm-dp-change-aux-dpcd-probe-address-from-dpcd_rev-to-lane0_1_status.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From imre.deak@intel.com  Tue Sep  2 13:49:03 2025
From: Imre Deak <imre.deak@intel.com>
Date: Thu, 28 Aug 2025 20:49:27 +0300
Subject: Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"
To: <stable@vger.kernel.org>
Cc: <intel-gfx@lists.freedesktop.org>, <dri-devel@lists.freedesktop.org>, Sasha Levin <sashal@kernel.org>
Message-ID: <20250828174932.414566-2-imre.deak@intel.com>

From: Imre Deak <imre.deak@intel.com>

This reverts commit 89d17a2d89a83c5b7643ca934651a3f9229e4734 which is
commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f upstream.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/drm_dp_helper.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -299,7 +299,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_a
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
 	if (!aux->is_remote) {
-		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_LANE0_1_STATUS,
+		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV,
 					 buffer, 1);
 		if (ret != 1)
 			goto out;


Patches currently in stable-queue which might be from imre.deak@intel.com are

queue-5.10/revert-drm-dp-change-aux-dpcd-probe-address-from-dpcd_rev-to-lane0_1_status.patch

[PATCH 5.15.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

This reverts commit a19b31f854a8992dfa35255f43efd19be292b15c.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index e830e461edd1..b8815e7f5832 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -336,7 +336,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
 	if (!aux->is_remote) {
-		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_LANE0_1_STATUS,
+		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV,
 					 buffer, 1);
 		if (ret != 1)
 			goto out;
-- 
2.49.1

[PATCH 6.1.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

This reverts commit 4f546a77671076a0a49c08b4c6a7d0888d72f7d2.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index ecb30e17d50c..e839981c7b2f 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -663,7 +663,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
 	if (!aux->is_remote) {
-		ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
+		ret = drm_dp_dpcd_probe(aux, DP_DPCD_REV);
 		if (ret < 0)
 			return ret;
 	}
-- 
2.49.1

Patch "Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"" has been added to the 6.1-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     revert-drm-dp-change-aux-dpcd-probe-address-from-dpcd_rev-to-lane0_1_status.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From imre.deak@intel.com  Tue Sep  2 13:50:59 2025
From: Imre Deak <imre.deak@intel.com>
Date: Thu, 28 Aug 2025 20:49:29 +0300
Subject: Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"
To: <stable@vger.kernel.org>
Cc: <intel-gfx@lists.freedesktop.org>, <dri-devel@lists.freedesktop.org>, Sasha Levin <sashal@kernel.org>
Message-ID: <20250828174932.414566-4-imre.deak@intel.com>

From: Imre Deak <imre.deak@intel.com>

This reverts commit 4f546a77671076a0a49c08b4c6a7d0888d72f7d2 which is
commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f upstream.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/display/drm_dp_helper.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -663,7 +663,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_a
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
 	if (!aux->is_remote) {
-		ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
+		ret = drm_dp_dpcd_probe(aux, DP_DPCD_REV);
 		if (ret < 0)
 			return ret;
 	}


Patches currently in stable-queue which might be from imre.deak@intel.com are

queue-6.1/revert-drm-dp-change-aux-dpcd-probe-address-from-dpcd_rev-to-lane0_1_status.patch

[PATCH 6.6.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

This reverts commit 65e46aeaf84aa88539bcff6b8077e05fbd0700da.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 772d8e662278..851f0baf9460 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -663,7 +663,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
 	if (!aux->is_remote) {
-		ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
+		ret = drm_dp_dpcd_probe(aux, DP_DPCD_REV);
 		if (ret < 0)
 			return ret;
 	}
-- 
2.49.1

[PATCH 6.12.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

This reverts commit 3c778a98bee16b4c7ba364a0101ee3c399a95b85.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index bb61bbdcce5b..9fa13da513d2 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -664,7 +664,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
 	if (!aux->is_remote) {
-		ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
+		ret = drm_dp_dpcd_probe(aux, DP_DPCD_REV);
 		if (ret < 0)
 			return ret;
 	}
-- 
2.49.1

[PATCH 6.16.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

This reverts commit 944e732be9c3a33e64e9fb0f5451a37fc252ddfc.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index dc622c78db9d..ea78c6c8ca7a 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -725,7 +725,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
 	if (!aux->is_remote) {
-		ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
+		ret = drm_dp_dpcd_probe(aux, DP_TRAINING_PATTERN_SET);
 		if (ret < 0)
 			return ret;
 	}
-- 
2.49.1

Re: [PATCH 6.16.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Wolfgang Frisch]

[-- Attachment #1.1: Type: text/plain, Size: 1437 bytes --]

Hi,

On 8/28/25 7:49 PM, Imre Deak wrote:
> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
> -		ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
> +		ret = drm_dp_dpcd_probe(aux, DP_TRAINING_PATTERN_SET);
The original commit d34d6feaf4a76833effcec0b148b65946b04cde8 broke my 
setup, with a monitor connected via Thunderbolt. Linux 6.16.4 
temporarily fixed the issue by reverting to DP_LANE0_1_STATUS. My 
monitor is a Samsung C34J79x connected via Thunderbolt 3.

To be clear:
- working: DP_LANE0_1_STATUS
- not working: DP_TRAINING_PATTERN_SET

With the latter I get:
> +thunderbolt 0000:c5:00.6: 2: timeout reading config space 2 from 0x20
> +thunderbolt 0000:c5:00.6: 2: timeout reading config space 2 from 0x5
> +thunderbolt 0000:c5:00.6: 2: cannot find TB_VSE_CAP_PLUG_EVENTS aborting
>  thunderbolt 1-2: new device found, vendor=0x175 device=0x20ab
>  thunderbolt 1-2: SAMSUNG ELECTRONICS CO.,LTD C34J79x
>  thunderbolt 1-0:2.1: new retimer found, vendor=0x1da0 device=0x8830
> +thunderbolt 0000:c5:00.6: 0:6 <-> 2:10 (DP): not active, tearing down
> +thunderbolt 0000:c5:00.6: 0:7 <-> 2:10 (DP): not active, tearing down

Best regards

-- 
Wolfgang Frisch <wolfgang.frisch@suse.com>
Security Engineer
OpenPGP fingerprint: A2E6 B7D4 53E9 544F BC13  D26B D9B3 56BD 4D4A 2D15
SUSE Software Solutions Germany GmbH, Frankenstraße 146, 90461 Nürnberg


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 840 bytes --]

Re: [PATCH 6.16.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

[-- Attachment #1: Type: text/plain, Size: 2405 bytes --]

Hi Wolfgang,

On Tue, Sep 02, 2025 at 04:32:10PM +0200, Wolfgang Frisch wrote:
> Hi,
> 
> On 8/28/25 7:49 PM, Imre Deak wrote:
> > diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
> > -		ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
> > +		ret = drm_dp_dpcd_probe(aux, DP_TRAINING_PATTERN_SET);
> The original commit d34d6feaf4a76833effcec0b148b65946b04cde8 broke my setup,
> with a monitor connected via Thunderbolt. Linux 6.16.4 temporarily fixed the
> issue by reverting to DP_LANE0_1_STATUS. My monitor is a Samsung C34J79x
> connected via Thunderbolt 3.
> 
> To be clear:
> - working: DP_LANE0_1_STATUS
> - not working: DP_TRAINING_PATTERN_SET

This looks like the issue tracked at
https://gitlab.freedesktop.org/drm/amd/-/issues/4500

The correct solution there is to disable the DPCD probing, which AMD
folks are working on atm. Until that, could you give a go to patch [1]
on the above ticket equivalent to this solution, applying on v6.17, or
the attached patch achieving the same on v6.16.4?

Also it would help if you could add a dmesg log on the ticket taken
after booting with drm.debug=0x100 and reproducing the problem (vs. two
other drm.debug=0x100 logs, one with the above DP_TRAINING_PATTERN_SET
-> DP_LANE0_1_STATUS change and another one with DPCD probing disabled
as I requested above, taken after booting up and connecting the
dock/monitor).

Thanks,
Imre

[1] https://gitlab.freedesktop.org/-/project/4522/uploads/8b39006b61fe67674d9b41fd92224c32/0001-drm-dp-Disable-DPCD-probing.patch

> With the latter I get:
> > +thunderbolt 0000:c5:00.6: 2: timeout reading config space 2 from 0x20
> > +thunderbolt 0000:c5:00.6: 2: timeout reading config space 2 from 0x5
> > +thunderbolt 0000:c5:00.6: 2: cannot find TB_VSE_CAP_PLUG_EVENTS aborting
> >  thunderbolt 1-2: new device found, vendor=0x175 device=0x20ab
> >  thunderbolt 1-2: SAMSUNG ELECTRONICS CO.,LTD C34J79x
> >  thunderbolt 1-0:2.1: new retimer found, vendor=0x1da0 device=0x8830
> > +thunderbolt 0000:c5:00.6: 0:6 <-> 2:10 (DP): not active, tearing down
> > +thunderbolt 0000:c5:00.6: 0:7 <-> 2:10 (DP): not active, tearing down
> 
> Best regards
> 
> -- 
> Wolfgang Frisch <wolfgang.frisch@suse.com>
> Security Engineer
> OpenPGP fingerprint: A2E6 B7D4 53E9 544F BC13  D26B D9B3 56BD 4D4A 2D15
> SUSE Software Solutions Germany GmbH, Frankenstraße 146, 90461 Nürnberg
> 




[-- Attachment #2: drm-dp-Disable-DPCD-probing-v6.16.patch --]
[-- Type: text/x-diff, Size: 597 bytes --]

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index dc622c78db9d..ec53c545776f 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -724,7 +724,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 	 * We just have to do it before any DPCD access and hope that the
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
-	if (!aux->is_remote) {
+	if (0 && !aux->is_remote) {
 		ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS);
 		if (ret < 0)
 			return ret;

Re: [PATCH 6.16.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Wolfgang Frisch]

[-- Attachment #1.1: Type: text/plain, Size: 1346 bytes --]

Hi Imre,


On 9/2/25 6:13 PM, Imre Deak wrote:
> This looks like the issue tracked at
> https://gitlab.freedesktop.org/drm/amd/-/issues/4500
Thanks! I wasn't aware of that issue being tracked already.

> The correct solution there is to disable the DPCD probing, which AMD
> folks are working on atm. Until that, could you give a go to patch [1]
> on the above ticket equivalent to this solution, applying on v6.17, or
> the attached patch achieving the same on v6.16.4?
I can confirm your patch fixes the issue on v6.16.4.
> Also it would help if you could add a dmesg log on the ticket taken
> after booting with drm.debug=0x100 and reproducing the problem (vs. two
> other drm.debug=0x100 logs, one with the above DP_TRAINING_PATTERN_SET
> -> DP_LANE0_1_STATUS change and another one with DPCD probing disabled
> as I requested above, taken after booting up and connecting the
> dock/monitor).
Done. I attached 3 dmesg logs to the ticket:

- GOOD: Linux 6.16.4 with DPCD probing disabled
- BAD: Linux 6.17.0-rc4
- GOOD: Linux 6.17.0-rc4 with the probe address set to DP_LANE0_1_STATUS


Regards,

-- 
Wolfgang Frisch <wolfgang.frisch@suse.com>
Security Engineer
OpenPGP fingerprint: A2E6 B7D4 53E9 544F BC13  D26B D9B3 56BD 4D4A 2D15
SUSE Software Solutions Germany GmbH, Frankenstraße 146, 90461 Nürnberg


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 840 bytes --]

Re: [PATCH 6.16.y] Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

[Imre Deak]

On Thu, Sep 04, 2025 at 03:20:23PM +0200, Wolfgang Frisch wrote:
> Hi Imre,
> 
> 
> On 9/2/25 6:13 PM, Imre Deak wrote:
> > This looks like the issue tracked at
> > https://gitlab.freedesktop.org/drm/amd/-/issues/4500
> Thanks! I wasn't aware of that issue being tracked already.
> 
> > The correct solution there is to disable the DPCD probing, which AMD
> > folks are working on atm. Until that, could you give a go to patch [1]
> > on the above ticket equivalent to this solution, applying on v6.17, or
> > the attached patch achieving the same on v6.16.4?
> I can confirm your patch fixes the issue on v6.16.4.
> > Also it would help if you could add a dmesg log on the ticket taken
> > after booting with drm.debug=0x100 and reproducing the problem (vs. two
> > other drm.debug=0x100 logs, one with the above DP_TRAINING_PATTERN_SET
> > -> DP_LANE0_1_STATUS change and another one with DPCD probing disabled
> > as I requested above, taken after booting up and connecting the
> > dock/monitor).
> Done. I attached 3 dmesg logs to the ticket:

Thanks for the testing.

> - GOOD: Linux 6.16.4 with DPCD probing disabled
> - BAD: Linux 6.17.0-rc4

This is expected, as it still does DPCD probing leading to the original
TBT firmware issue tracked on the above ticket.

> - GOOD: Linux 6.17.0-rc4 with the probe address set to DP_LANE0_1_STATUS

Switching the DPCD probing address to DP_LANE0_1_STATUS is not a viable
solution, as it causes an issue for at least one other (eDP) panel. The
probing should be disabled according to the following AMD patch:

https://gitlab.freedesktop.org/-/project/4522/uploads/5205fd4e2bdc396088836bafcac176b6/0004-drm-amd-display-Disable-DPCD-Probe-Quirk.patch

--Imre

> Regards,
> 
> -- 
> Wolfgang Frisch <wolfgang.frisch@suse.com>
> Security Engineer
> OpenPGP fingerprint: A2E6 B7D4 53E9 544F BC13  D26B D9B3 56BD 4D4A 2D15
> SUSE Software Solutions Germany GmbH, Frankenstraße 146, 90461 Nürnberg
> 

✗ Fi.CI.BUILD: failure for Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS" (rev7)

[Patchwork]

== Series Details ==

Series: Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS" (rev7)
URL   : https://patchwork.freedesktop.org/series/153652/
State : failure

== Summary ==

Error: patch https://patchwork.freedesktop.org/api/1.0/series/153652/revisions/7/mbox/ not applied
Applying: Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"
Using index info to reconstruct a base tree...
M	drivers/gpu/drm/display/drm_dp_helper.c
Falling back to patching base and 3-way merge...
Auto-merging drivers/gpu/drm/display/drm_dp_helper.c
CONFLICT (content): Merge conflict in drivers/gpu/drm/display/drm_dp_helper.c
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
Build failed, no error log produced

Patch "Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"" has been added to the 5.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     revert-drm-dp-change-aux-dpcd-probe-address-from-dpcd_rev-to-lane0_1_status.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From imre.deak@intel.com  Tue Sep  2 13:42:52 2025
From: Imre Deak <imre.deak@intel.com>
Date: Thu, 28 Aug 2025 20:49:26 +0300
Subject: Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"
To: <stable@vger.kernel.org>
Cc: <intel-gfx@lists.freedesktop.org>, <dri-devel@lists.freedesktop.org>, Sasha Levin <sashal@kernel.org>
Message-ID: <20250828174932.414566-1-imre.deak@intel.com>

From: Imre Deak <imre.deak@intel.com>

This reverts commit 2402adce8da4e7396b63b5ffa71e1fa16e5fe5c4 which is
commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f upstream.

The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp:
Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the
reverted commit backported causes a regression, on one eDP panel at
least resulting in display flickering, described in detail at the Link:
below. The issue fixed by the upstream commit will need a different
solution, revert the backport for now.

Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Sasha Levin <sashal@kernel.org>
Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/drm_dp_helper.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -280,7 +280,7 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_a
 	 * We just have to do it before any DPCD access and hope that the
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
-	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_LANE0_1_STATUS, buffer,
+	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer,
 				 1);
 	if (ret != 1)
 		goto out;


Patches currently in stable-queue which might be from imre.deak@intel.com are

queue-5.4/revert-drm-dp-change-aux-dpcd-probe-address-from-dpcd_rev-to-lane0_1_status.patch

✗ Fi.CI.BUILD: failure for Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS" (rev8)

[Patchwork]

== Series Details ==

Series: Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS" (rev8)
URL   : https://patchwork.freedesktop.org/series/153652/
State : failure

== Summary ==

Error: patch https://patchwork.freedesktop.org/api/1.0/series/153652/revisions/8/mbox/ not applied
Applying: Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"
Using index info to reconstruct a base tree...
M	drivers/gpu/drm/display/drm_dp_helper.c
Falling back to patching base and 3-way merge...
Auto-merging drivers/gpu/drm/display/drm_dp_helper.c
CONFLICT (content): Merge conflict in drivers/gpu/drm/display/drm_dp_helper.c
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Revert "drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS"
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
Build failed, no error log produced