target/linux/layerscape/patches-5.4/805-display-0053-LF-323-2-drm-bridge-cdns-enhance-link-training-stabi.patch

   1 From 06b758a32bb5ca164cff60f20173ecd71508c5ae Mon Sep 17 00:00:00 2001
   2 From: Sandor Yu <Sandor.yu@nxp.com>
   3 Date: Mon, 9 Dec 2019 17:58:29 +0800
   4 Subject: [PATCH] LF-323-2: drm/bridge/cdns: enhance link training stability
   5
   6 Remove drm_dp_link_power_down from bridge_disable function,
   7 in case some DP sinks aren't follow DP 1.1 specification
   8 and can not exit the power saving state within 1 ms.
   9 Add drm_dp_link_power_up to bridge_enable function,
  10 make sure DP sinks are power up before link training.
  11
  12 Signed-off-by: Sandor Yu <Sandor.yu@nxp.com>
  13 Reviewed-by: Robby Cai <robby.cai@nxp.com>
  14 ---
  15  drivers/gpu/drm/bridge/cadence/cdns-dp-core.c | 3 ++-
  16  1 file changed, 2 insertions(+), 1 deletion(-)
  17
  18 --- a/drivers/gpu/drm/bridge/cadence/cdns-dp-core.c
  19 +++ b/drivers/gpu/drm/bridge/cadence/cdns-dp-core.c
  20 @@ -329,6 +329,8 @@ static void cdn_hdp_bridge_enable(struct
  21         struct cdns_mhdp_device *mhdp = bridge->driver_private;
  22         int ret;
  23
  24 +       drm_dp_link_power_up(&mhdp->dp.aux, &mhdp->dp.link);
  25 +
  26         /* Link trainning */
  27         ret = cdns_mhdp_train_link(mhdp);
  28         if (ret) {
  29 @@ -348,7 +350,6 @@ static void cdn_hdp_bridge_disable(struc
  30         struct cdns_mhdp_device *mhdp = bridge->driver_private;
  31
  32         cdns_mhdp_set_video_status(mhdp, CONTROL_VIDEO_IDLE);
  33 -       drm_dp_link_power_down(&mhdp->dp.aux, &mhdp->dp.link);
  34  }
  35
  36  static const struct drm_bridge_funcs cdns_dp_bridge_funcs = {