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Fix drm_dp_send_dpcd_write() return code

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Justin M. Forbes 2020-04-28 10:25:57 -05:00
commit 2b7942c5c9
2 changed files with 52 additions and 0 deletions
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47
drm-dp_mst-Fix-drm_dp_send_dpcd_write-return-code.patch Normal file
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@ -0,0 +1,47 @@
From: Lyude Paul <lyude@redhat.com>
Date: Fri, 24 Apr 2020 15:07:22 -0400
Subject: drm/dp_mst: Fix drm_dp_send_dpcd_write() return code
drm_dp_mst_wait_tx_reply() returns > 1 if time elapsed in
wait_event_timeout() before check_txmsg_state(mgr, txmsg) evaluated to
true. However, we make the mistake of returning this time from
drm_dp_send_dpcd_write() on success instead of returning the number of
bytes written - causing spontaneous failures during link probing:
[drm:drm_dp_send_link_address [drm_kms_helper]] *ERROR* GUID check on
10:01 failed: 3975
Yikes! So, fix this by returning the number of bytes written on success
instead.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: cb897542c6d2 ("drm/dp_mst: Fix W=1 warnings")
Cc: Benjamin Gaignard <benjamin.gaignard@st.com>
Cc: Sean Paul <sean@poorly.run>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Sean Paul <sean@poorly.run>
Link: https://patchwork.freedesktop.org/patch/msgid/20200424190722.775284-1-lyude@redhat.com
---
drivers/gpu/drm/drm_dp_mst_topology.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 03a1496f6120..21dc78cb4ba6 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3436,8 +3436,12 @@ static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
drm_dp_queue_down_tx(mgr, txmsg);
ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
- if (ret > 0 && txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
- ret = -EIO;
+ if (ret > 0) {
+ if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
+ ret = -EIO;
+ else
+ ret = size;
+ }
kfree(txmsg);
fail_put:

5
kernel.spec
View file

@ -610,6 +610,8 @@ Patch509: drm-i915-backports.patch
# https://patchwork.ozlabs.org/patch/1260523/
Patch511: e1000e-bump-up-timeout-to-wait-when-ME-un-configure-ULP-mode.patch
Patch512: drm-dp_mst-Fix-drm_dp_send_dpcd_write-return-code.patch
# END OF PATCH DEFINITIONS
%endif
@ -1839,6 +1841,9 @@ fi
#
#
%changelog
* Tue Apr 28 2020 Justin M. Forbes <jforbes@fedoraproject.org>
- MST Fix from Lyude Paul
* Fri Apr 24 2020 Justin M. Forbes <jforbes@fedoraproject.org> - 5.6.7-100
- Linux v5.6.7 rebase