[PATCH v4 00/78] drm/vc4: Support BCM2711 Display Pipeline

[Jian-Hong Pan]

Hi Maxime,

Thanks for your version 4 patch again.
I took the patches and applied them upon next-20200708.

I make system cold reboot to multi-user target and the text console shows on the
screen. Then, I simply hot re-plug the HDMI cable on HDMI0 port, I not only lose
the text console on the screen (the display shows blank, backlight is off), but
also kernel does not probe modes for the HDMI connector again.

But HDMI1 does probe modes again for hot re-plugging. So, HDMI1 does not hit the
issue like HDMI0.

* System probes modes only once for HDMI0 port (HDMI-A-1), even hot re-plug HDMI
  cable to the same port:

[   15.611072] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:32:HDMI-A-1] probed modes :
[   15.611079] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x48 0x5
[   15.611085] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
...
[   15.611298] [drm:drm_mode_debug_printmodeline] Modeline "720x400": 70 28320 720 738 846 900 400 412 414 449 0x40 0x6
[   15.611303] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:38:HDMI-A-2]
[   15.612184] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:38:HDMI-A-2] disconnected
[   15.612191] [drm:drm_client_modeset_probe] connector 32 enabled? yes
[   15.612194] [drm:drm_client_modeset_probe] connector 38 enabled? no
[   15.612206] [drm:drm_client_modeset_probe] Not using firmware configuration
[   15.612213] [drm:drm_client_modeset_probe] looking for cmdline mode on connector 32
[   15.612218] [drm:drm_client_modeset_probe] looking for preferred mode on connector 32 0
[   15.612221] [drm:drm_client_modeset_probe] found mode 1920x1080
...
[  108.263384] [drm:output_poll_execute] [CONNECTOR:32:HDMI-A-1] status updated from disconnected to connected
[  108.264307] vc4-drm gpu: [drm:drm_fb_helper_hotplug_event.part.0] 
[  108.264312] [drm:drm_client_modeset_probe] 
[  108.264321] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:32:HDMI-A-1]
[  109.303379] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:38:HDMI-A-2]
[  109.304258] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:38:HDMI-A-2] disconnected
[  109.304266] [drm:drm_client_modeset_probe] No connectors reported connected with modes

* System probes modes again for HDMI1 port (HDMI-A-2), whenever hot re-plug the
  HDMI cable:

[  797.974649] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:38:HDMI-A-2] probed modes :
[  797.974656] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x48 0x5
[  797.974662] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
...
[  797.974874] [drm:drm_mode_debug_printmodeline] Modeline "720x400": 70 28320 720 738 846 900 400 412 414 449 0x40 0x6
[  797.974880] [drm:drm_client_modeset_probe] connector 32 enabled? no
[  797.974883] [drm:drm_client_modeset_probe] connector 38 enabled? yes
[  797.974895] [drm:drm_client_modeset_probe] Not using firmware configuration
[  797.974901] [drm:drm_client_modeset_probe] looking for cmdline mode on connector 38
[  797.974905] [drm:drm_client_modeset_probe] looking for preferred mode on connector 38 0
[  797.974908] [drm:drm_client_modeset_probe] found mode 1920x1080
...
[  852.242615] vc4-drm gpu: [drm:drm_client_dev_hotplug] fbdev: ret=0
[  873.718277] [drm:output_poll_execute] [CONNECTOR:38:HDMI-A-2] status updated from disconnected to connected
[  873.718332] vc4-drm gpu: [drm:drm_fb_helper_hotplug_event.part.0] 
[  873.718338] [drm:drm_client_modeset_probe]
...
[  874.264013] [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:38:HDMI-A-2] probed modes :
[  874.264020] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x48 0x5
[  874.264026] [drm:drm_mode_debug_printmodeline] Modeline "1920x1080": 60 148500 1920 2008 2052 2200 1080 1084 1089 1125 0x40 0x5
...
[  874.264239] [drm:drm_mode_debug_printmodeline] Modeline "720x400": 70 28320 720 738 846 900 400 412 414 449 0x40 0x6
[  874.264244] [drm:drm_client_modeset_probe] connector 32 enabled? no
[  874.264247] [drm:drm_client_modeset_probe] connector 38 enabled? yes
[  874.264259] [drm:drm_client_modeset_probe] Not using firmware configuration
[  874.264264] [drm:drm_client_modeset_probe] looking for cmdline mode on connector 38
[  874.264268] [drm:drm_client_modeset_probe] looking for preferred mode on connector 38 0
[  874.264272] [drm:drm_client_modeset_probe] found mode 1920x1080

Here is the full dmesg: https://gist.github.com/starnight/5ffb86af552fedb9b6e5741d0540a878#file-dmesg-v4-log