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authorWayne Lin <Wayne.Lin@amd.com>2020-01-13 12:36:49 +0300
committerLyude Paul <lyude@redhat.com>2020-01-16 01:01:21 +0300
commit5a64967a2f3bbc01cc708ee43c7b0893089c61c4 (patch)
tree67cab3ff97971a640fbfa2ffeb54f0afc5c63c32 /include
parent7617e9621bf2ca3bb58d5f216cc35c86b029105d (diff)
downloadlinux-5a64967a2f3bbc01cc708ee43c7b0893089c61c4.tar.xz
drm/dp_mst: Have DP_Tx send one msg at a time
[Why] Noticed this while testing MST with the 4 ports MST hub from StarTech.com. Sometimes can't light up monitors normally and get the error message as 'sideband msg build failed'. Look into aux transactions, found out that source sometimes will send out another down request before receiving the down reply of the previous down request. On the other hand, in drm_dp_get_one_sb_msg(), current code doesn't handle the interleaved replies case. Hence, source can't build up message completely and can't light up monitors. [How] For good compatibility, enforce source to send out one down request at a time. Add a flag, is_waiting_for_dwn_reply, to determine if the source can send out a down request immediately or not. - Check the flag before calling process_single_down_tx_qlock to send out a msg - Set the flag when successfully send out a down request - Clear the flag when successfully build up a down reply - Clear the flag when find erros during sending out a down request - Clear the flag when find errors during building up a down reply - Clear the flag when timeout occurs during waiting for a down reply - Use drm_dp_mst_kick_tx() to try to send another down request in queue at the end of drm_dp_mst_wait_tx_reply() (attempt to send out messages in queue when errors occur) Cc: Lyude Paul <lyude@redhat.com> Signed-off-by: Wayne Lin <Wayne.Lin@amd.com> Signed-off-by: Lyude Paul <lyude@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200113093649.11755-1-Wayne.Lin@amd.com
Diffstat (limited to 'include')
-rw-r--r--include/drm/drm_dp_mst_helper.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index d5fc90b30487..c1bda7030e2d 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -605,6 +605,12 @@ struct drm_dp_mst_topology_mgr {
* &drm_dp_sideband_msg_tx.state once they are queued
*/
struct mutex qlock;
+
+ /**
+ * @is_waiting_for_dwn_reply: indicate whether is waiting for down reply
+ */
+ bool is_waiting_for_dwn_reply;
+
/**
* @tx_msg_downq: List of pending down replies.
*/