On 3/17/26 10:03 PM, Dmitry Baryshkov wrote:
On Tue, Mar 17, 2026 at 08:15:54PM -0300, Val Packett wrote:
On 3/16/26 12:23 AM, Dmitry Baryshkov wrote:
On Sat, Mar 14, 2026 at 10:10:26PM -0300, Val Packett wrote:
On 3/14/26 9:51 PM, Val Packett wrote:
On 3/13/26 10:09 PM, Dmitry Baryshkov wrote:
Currently, all HPD interrupt handling must go through the HPD state
machine.
This has caused many issues where the DRM framework assumes that DP is
in one state while the state machine is stuck in another state.
As discussed here [1], this series:
- Removes the state machine
- Moves link training to atomic_enable()
- Changes the detect() behavior to return true if a display is
physically
plugged in (as opposed to if the DP link is ready).
- Remove event queue and move internal HPD handling to hpd_notify()
To correctly detect the displays which are plugged on boot on the boards
which use dp-connector devices, this series depends on [2]. USB-C and
eDP panels are handled natively.
[1]
https://patchwork.freedesktop.org/patch/656312/?series=142010&rev=2#comment_1201738
[2]
https://lore.kernel.org/all/[email protected]/
Unfortunately this currently seems to mostly break link training with
USB-C, on x1e80100-dell-latitude-7455:
[ 102.190083] [drm:msm_dp_ctrl_link_train_1_2 [msm]] *ERROR* link
training #2 on phy 1 failed. ret=-110
[ 102.192846] [drm:msm_dp_ctrl_setup_main_link [msm]] *ERROR* link
training of LTTPR(s) failed. ret=-110
[ 102.211095] [drm:msm_dp_bridge_atomic_enable [msm]] *ERROR* Failed
link training (rc=-104)
[ 102.211164] [drm:msm_dp_aux_isr [msm]] *ERROR* Unexpected DP AUX IRQ
0x01000000 when not busy
[ 102.247168] [drm:msm_dp_ctrl_link_train_1_2 [msm]] *ERROR* link
training #2 on phy 1 failed. ret=-110
[ 102.252859] [drm:msm_dp_ctrl_setup_main_link [msm]] *ERROR* link
training of LTTPR(s) failed. ret=-110
[..]
Actually looks like that might've been due to having applied the [2]
dp-connector series from above.
Interesting. The series only affects dp-connector. It can't affect
pmic-glink usecase.
Removed it and rebooted, now plugging and unplugging multiple times between
the 2 ports works fine.
Except unplug is still not reliable, the "ghost" monitor often remains after
unplugging.
Does the patch at [3] fix the issue?
[3]
https://lore.kernel.org/linux-arm-msm/[email protected]/
Yes!
Overall works better than ever now, looks like I can unplug the cable with
the laptop closed and then open it and it's all fine, and even play with
dual-role / gadget mode USB and plug the alt-mode/dock cable back in and it
doesn't crash.
Tested-by?
Yeah, since I guess the link training is kinda orthogonal to this, sure!
Tested-by: Val Packett <[email protected]> # x1e80100-dell-latitude-7455
Still, rare link training failures can happen, e.g.:
Thanks!
The link training is one of the items that I want to check next.
