[AMD Public Use]
Hi Paul,
Thanks for the mail!
I tried to solve this problem by having restriction on sending one msg at a time due to hub/dock compatibility problems.
>From my experience, some branch devices don't handle well on interleaved replies (Dock from HP I think)
As the result of that, correct me if I'm wrong, I remember most gpu vendors just send one down request at a time now in windows environment.
I would suggest the original solution :)
Thanks!
> -----Original Message-----
> From: Sean Paul <sean@xxxxxxxxxx>
> Sent: Friday, February 14, 2020 5:15 AM
> To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: lyude@xxxxxxxxxx; Lin, Wayne <Wayne.Lin@xxxxxxx>; Sean Paul
> <seanpaul@xxxxxxxxxxxx>; Maarten Lankhorst
> <maarten.lankhorst@xxxxxxxxxxxxxxx>; Maxime Ripard <mripard@xxxxxxxxxx>;
> David Airlie <airlied@xxxxxxxx>
> Subject: [PATCH 3/3] drm/dp_mst: Remove single tx msg restriction.
>
> From: Sean Paul <seanpaul@xxxxxxxxxxxx>
>
> Now that we can support multiple simultaneous replies, remove the
> restrictions placed on sending new tx msgs.
>
> This patch essentially just reverts commit
> 5a64967a2f3b ("drm/dp_mst: Have DP_Tx send one msg at a time") now
> that the problem is solved in a different way.
>
> Cc: Wayne Lin <Wayne.Lin@xxxxxxx>
> Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_mst_topology.c | 14 ++------------
> include/drm/drm_dp_mst_helper.h | 6 ------
> 2 files changed, 2 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 7e6a82efdfc02..cbf0bb0ddeb84 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -1203,8 +1203,6 @@ static int drm_dp_mst_wait_tx_reply(struct
> drm_dp_mst_branch *mstb,
> txmsg->state == DRM_DP_SIDEBAND_TX_SENT) {
> mstb->tx_slots[txmsg->seqno] = NULL;
> }
> - mgr->is_waiting_for_dwn_reply = false;
> -
> }
> out:
> if (unlikely(ret == -EIO) && drm_debug_enabled(DRM_UT_DP)) { @@
> -1214,7 +1212,6 @@ static int drm_dp_mst_wait_tx_reply(struct
> drm_dp_mst_branch *mstb,
> }
> mutex_unlock(&mgr->qlock);
>
> - drm_dp_mst_kick_tx(mgr);
> return ret;
> }
>
> @@ -2797,11 +2794,9 @@ static void process_single_down_tx_qlock(struct
> drm_dp_mst_topology_mgr *mgr)
> ret = process_single_tx_qlock(mgr, txmsg, false);
> if (ret == 1) {
> /* txmsg is sent it should be in the slots now */
> - mgr->is_waiting_for_dwn_reply = true;
> list_del(&txmsg->next);
> } else if (ret) {
> DRM_DEBUG_KMS("failed to send msg in q %d\n", ret);
> - mgr->is_waiting_for_dwn_reply = false;
> list_del(&txmsg->next);
> if (txmsg->seqno != -1)
> txmsg->dst->tx_slots[txmsg->seqno] = NULL; @@ -2841,8
> +2836,7 @@ static void drm_dp_queue_down_tx(struct
> drm_dp_mst_topology_mgr *mgr,
> drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
> }
>
> - if (list_is_singular(&mgr->tx_msg_downq) &&
> - !mgr->is_waiting_for_dwn_reply)
> + if (list_is_singular(&mgr->tx_msg_downq))
> process_single_down_tx_qlock(mgr);
> mutex_unlock(&mgr->qlock);
> }
> @@ -3822,7 +3816,6 @@ static int drm_dp_mst_handle_down_rep(struct
> drm_dp_mst_topology_mgr *mgr)
> mutex_lock(&mgr->qlock);
> txmsg->state = DRM_DP_SIDEBAND_TX_RX;
> mstb->tx_slots[seqno] = NULL;
> - mgr->is_waiting_for_dwn_reply = false;
> mutex_unlock(&mgr->qlock);
>
> wake_up_all(&mgr->tx_waitq);
> @@ -3830,9 +3823,6 @@ static int drm_dp_mst_handle_down_rep(struct
> drm_dp_mst_topology_mgr *mgr)
> return 0;
>
> out_clear_reply:
> - mutex_lock(&mgr->qlock);
> - mgr->is_waiting_for_dwn_reply = false;
> - mutex_unlock(&mgr->qlock);
> if (msg)
> memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
> out:
> @@ -4670,7 +4660,7 @@ static void drm_dp_tx_work(struct work_struct
> *work)
> struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct
> drm_dp_mst_topology_mgr, tx_work);
>
> mutex_lock(&mgr->qlock);
> - if (!list_empty(&mgr->tx_msg_downq)
> && !mgr->is_waiting_for_dwn_reply)
> + if (!list_empty(&mgr->tx_msg_downq))
> process_single_down_tx_qlock(mgr);
> mutex_unlock(&mgr->qlock);
> }
> diff --git a/include/drm/drm_dp_mst_helper.h
> b/include/drm/drm_dp_mst_helper.h index 7d0341f94ce1b..fcc30e64c8e7e
> 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -619,12 +619,6 @@ 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.
> */
> --
> Sean Paul, Software Engineer, Google / Chromium OS
--
Wayne Lin
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