This is a note to let you know that I've just added the patch titled
drm/amd/display: Fix deadlock when falling back to v2 from v3
to the 5.14-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:
drm-amd-display-fix-deadlock-when-falling-back-to-v2-from-v3.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ad76744b041d8c87ef1c9adbb04fb7eaa20a179e Mon Sep 17 00:00:00 2001
From: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
Date: Fri, 22 Oct 2021 16:14:24 -0400
Subject: drm/amd/display: Fix deadlock when falling back to v2 from v3
From: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
commit ad76744b041d8c87ef1c9adbb04fb7eaa20a179e upstream.
[Why]
A deadlock in the kernel occurs when we fallback from the V3 to V2
add_topology_to_display or remove_topology_to_display because they
both try to acquire the dtm_mutex but recursive locking isn't
supported on mutex_lock().
[How]
Make the mutex_lock/unlock more fine grained and move them up such that
they're only required for the psp invocation itself.
Fixes: bf62221e9d0e ("drm/amd/display: Add DCN3.1 HDCP support")
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
Reviewed-by: Aric Cyr <aric.cyr@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c
@@ -105,6 +105,7 @@ static enum mod_hdcp_status mod_hdcp_rem
dtm_cmd->dtm_status = TA_DTM_STATUS__GENERIC_FAILURE;
psp_dtm_invoke(psp, dtm_cmd->cmd_id);
+ mutex_unlock(&psp->dtm_context.mutex);
if (dtm_cmd->dtm_status != TA_DTM_STATUS__SUCCESS) {
status = mod_hdcp_remove_display_from_topology_v2(hdcp, index);
@@ -115,8 +116,6 @@ static enum mod_hdcp_status mod_hdcp_rem
HDCP_TOP_REMOVE_DISPLAY_TRACE(hdcp, display->index);
}
- mutex_unlock(&psp->dtm_context.mutex);
-
return status;
}
@@ -218,6 +217,7 @@ static enum mod_hdcp_status mod_hdcp_add
dtm_cmd->dtm_in_message.topology_update_v3.link_hdcp_cap = link->hdcp_supported_informational;
psp_dtm_invoke(psp, dtm_cmd->cmd_id);
+ mutex_unlock(&psp->dtm_context.mutex);
if (dtm_cmd->dtm_status != TA_DTM_STATUS__SUCCESS) {
status = mod_hdcp_add_display_to_topology_v2(hdcp, display);
@@ -227,8 +227,6 @@ static enum mod_hdcp_status mod_hdcp_add
HDCP_TOP_ADD_DISPLAY_TRACE(hdcp, display->index);
}
- mutex_unlock(&psp->dtm_context.mutex);
-
return status;
}
Patches currently in stable-queue which might be from nicholas.kazlauskas@xxxxxxx are
queue-5.14/drm-amd-display-require-immediate-flip-support-for-dcn3.1-planes.patch
queue-5.14/drm-amd-display-fallback-to-clocks-which-meet-requested-voltage-on-dcn31.patch
queue-5.14/drm-amd-display-fix-prefetch-bandwidth-calculation-for-dcn3.1.patch
queue-5.14/drm-amd-display-fix-deadlock-when-falling-back-to-v2-from-v3.patch
