[PATCH RESEND v3 0/5] drm/bridge: it6505: fix DP link traning and improve compatibility

[Hermes Wu via B4 Relay <devnull+Hermes.wu.ite.com.tw@kernel.org>]

IT6505 supports HW auto link training which will write DPCD and check
training status automatically. Some DP device can not pass
HW auto link training and must set link training step by step.

when HW auto link training fail, it may trigger video FIFO error,
and link training process will reset to beginning, and never try
step training method.

Modify training method improve compatibility to these DP devices.

Signed-off-by: Hermes Wu <Hermes.wu@ite.com.tw>
---
Changes in v3:
- Patch 1/5 : add commit message for detial about changes
- Patch 2/5 : fix lost variable struct device *dev;
- Patch 3/5 : keep changes and remove refactoring
- Patch 5/5 : merge condition "it6505->step_train_only" check form if condiction into for loop.
- Link to v2: https://lore.kernel.org/r/20250326-fix-link-training-v2-0-756c8306f500@ite.com.tw

Changes in v2:
- 1. Split [PATCH 1/3] into 3 commits
- 2. Drop non necessary variable auto_ttrain_retry
- Link to v1: https://lore.kernel.org/all/20250318-fix-link-training-v1-0-19266711142c@ite.com.tw/

---
Hermes Wu (5):
      drm/bridge: it6505: fix link training state HW register reset
      drm/bridge: it6505: check INT_LINK_TRAIN_FAIL while link auto training
      drm/bridge: it6505: modify DP link auto training
      drm/bridge: it6505: modify DP link training work
      drm/bridge: it6505: skip auto training when previous try fail

 drivers/gpu/drm/bridge/ite-it6505.c | 88 +++++++++++++++++++++----------------
 1 file changed, 50 insertions(+), 38 deletions(-)
---
base-commit: 938fbb16aba8f7b88e0fdcf56f315a5bbad41aad
change-id: 20250121-fix-link-training-461495494655

Best regards,
-- 
Hermes Wu <Hermes.wu@ite.com.tw>