This is a note to let you know that I've just added the patch titled
drm/dp_mst: Fix return code on sideband message failure
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-dp_mst-fix-return-code-on-sideband-message-failure.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 92bd92c44d0d9be5dcbcda315b4be4b909ed9740 Mon Sep 17 00:00:00 2001
From: Rajkumar Subbiah <rsubbia@xxxxxxxxxxxxxx>
Date: Tue, 6 Jul 2021 08:30:34 -0700
Subject: drm/dp_mst: Fix return code on sideband message failure
From: Rajkumar Subbiah <rsubbia@xxxxxxxxxxxxxx>
commit 92bd92c44d0d9be5dcbcda315b4be4b909ed9740 upstream.
Commit 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing +
selftests") added some debug code for sideband message tracing. But
it seems to have unintentionally changed the behavior on sideband message
failure. It catches and returns failure only if DRM_UT_DP is enabled.
Otherwise it ignores the error code and returns success. So on an MST
unplug, the caller is unaware that the clear payload message failed and
ends up waiting for 4 seconds for the response. Fixes the issue by
returning the proper error code.
Changes in V2:
-- Revise commit text as review comment
-- add Fixes text
Changes in V3:
-- remove "unlikely" optimization
Fixes: 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing + selftests")
Cc: <stable@xxxxxxxxxxxxxxx> # v5.5+
Signed-off-by: Rajkumar Subbiah <rsubbia@xxxxxxxxxxxxxx>
Signed-off-by: Kuogee Hsieh <khsieh@xxxxxxxxxxxxxx>
Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/1625585434-9562-1-git-send-email-khsieh@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2872,11 +2872,13 @@ static int process_single_tx_qlock(struc
idx += tosend + 1;
ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx);
- if (unlikely(ret) && drm_debug_enabled(DRM_UT_DP)) {
- struct drm_printer p = drm_debug_printer(DBG_PREFIX);
+ if (ret) {
+ if (drm_debug_enabled(DRM_UT_DP)) {
+ struct drm_printer p = drm_debug_printer(DBG_PREFIX);
- drm_printf(&p, "sideband msg failed to send\n");
- drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
+ drm_printf(&p, "sideband msg failed to send\n");
+ drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
+ }
return ret;
}
Patches currently in stable-queue which might be from rsubbia@xxxxxxxxxxxxxx are
queue-5.14/drm-dp_mst-fix-return-code-on-sideband-message-failure.patch
