Interfacing (DSI, CSI, I2C, etc.) • Re: DSI LCD works on Pi 5 but not on CM4 (same driver, same IC)

The Clock is always less than what is original set, I tried setting the clock to 55555 Khz, and in /sys/kernel/debug/clk/clk_summary the dsi1p was 41666668 Hz, and when i set the clock for 50000 khz, it was set for 37500 Khz in clk_summary, even so, any range from 24Mhz to 51.2Mhz should be acceptable to the screen anyways (tested on Pi 5)

when i set the clock to 50000 khz (which i think should be achievable - 37500 Khz in clk_summary) the fps was 60, so does that mean that CM4 did not alter the timing parameters right? because the LCD did not work yet, it does not even flicker or show any signs, its just black

The Driver does not send any initialization commands rather than: mipi_dsi_dcs_exit_sleep_mode(ctx->dsi);
could it be that Pi 5 sent some extra initialization commands automatically?
thats why it would work with Pi 5 and not CM4?


pi@raspberrypi:~$ kmstest --flip
Connector 0/@33: DSI-1
Crtc 2/@76: 1024x600@58.59 50.000 1024/160/80/80/? 600/12/10/13/? 59 (58.59) P|D
Plane 2/@65: 0,0-1024x600
Fb 709 1024x600-XR24
press enter to exit
Connector 0: fps 58.60, slowest 17.08 ms
Connector 0: fps 58.59, slowest 17.08 ms
Connector 0: fps 58.59, slowest 17.12 ms
Connector 0: fps 58.59, slowest 17.11 ms
Connector 0: fps 58.59, slowest 17.09 ms


[ 4.762909] panel_ronbo_rb070d30: loading out-of-tree module taints kernel.
[ 4.773077] panel-ronbo-rb070d30 fe700000.dsi.0: RB070D30 Panel probe started
[ 4.875328] panel-ronbo-rb070d30 fe700000.dsi.0: Panel GET_MODES called
[ 4.892202] panel-ronbo-rb070d30 fe700000.dsi.0: Panel PREPARE called
[ 4.964995] panel-ronbo-rb070d30 fe700000.dsi.0: Panel ENABLE called
[ 5.475974] panel-ronbo-rb070d30 fe700000.dsi.0: Failed to exit sleep mode in ENABLE func: -110
[ 5.555946] panel-ronbo-rb070d30 fe700000.dsi.0: Panel GET_MODES called
[ 5.568610] panel-ronbo-rb070d30 fe700000.dsi.0: RB070D30 Panel probe ended


pi@raspberrypi:~$ sudo cat /sys/kernel/debug/dri/1/crtc1_regs
PV_CONTROL = 0x00977001
PV_V_CONTROL = 0x0000000b
PV_VSYNCD_EVEN = 0x00000000
PV_HORZA = 0x00500050
PV_HORZB = 0x00a00400
PV_VERTA = 0x000d000a
PV_VERTB = 0x000c0258
PV_VERTA_EVEN = 0x00000000
PV_VERTB_EVEN = 0x00000000
PV_INTEN = 0x00000000
PV_INTSTAT = 0x00000000
PV_STAT = 0x00000644
PV_HACT_ACT = 0x00000400

Statistics: Posted by ORR — Mon Aug 11, 2025 7:25 am

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