To me, power cycling and rebooting are the same thing. I just power cycle I after I re-configure the parameters in the config.txt file. Sorry to have caused confusion there.To make sure I understand the issue: You have working configurations for both 4-lane and 2-lane operation, they both work correctly after a power cycle, but not after a reboot (when switching in either direction)?
EDIT: What about rebooting without having changed the DSI configuration - does that work?
The issue arises when switching between 4-lane and 2-lane DSI configurations. Here’s how it occurs:
1) Using the official Raspberry Pi imager, I loaded the latest version (6.6.37-v8-16k+ ) of Raspbian onto an SD card, which should include update #6157. This update resolved a 4-lane DSI issue we had with the previous Raspbian version.
2) I added the following parameters to config.txt to enable 4-lane DSI:
dtoverlay=vc4-kms-dsi-generic
dtparam=four-lane=1,hactive=3200
dtparam=vactive=1200
dtparam=vfp=96,vbp=12,hfp=90,hbp=90
dtparam=vsync=24,hsync=180
dtparam=clock-frequency=120000000
dtparam=dsi0=1
After adding the parameters, I power cycled the RPI and the 4-lane DSI worked and was validated with physical displays.
3) Then, I changed the configuration to 2-lane (dtparam=two-lane=1) and power cycled RPI. This also worked and was validated with physical displays.
4) However, when I switched back to 4-lane (dtparam=four-lane=1) and power cycled, the 4-lane DSI did not start. Multiple power cycles didn’t help, and neither the MIPI analyzer nor the displays showed any video. Changing the DSI timing parameters also didn’t resolve the issue.
5) I then reverted to 2-lane, and it worked again on physical displays. MIPI analyzer results also validated the 2-lane DSI output. It seems the DSI output becomes 'stuck' at the last configuration used, unable to toggle reliably between 4-lane and 2-lane.
When starting in either mode (4-lane or 2-lane), DSI only works for the initial setup, but subsequent attempts to switch modes cause it to remain fixed at the last applied configuration.
Statistics: Posted by ckarabul — Fri Nov 01, 2024 9:43 am
