Hi Paul, > Am 16.06.2023 um 22:21 schrieb H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>: > - But renaming the DT nodes (e.g. SUDCDC1 -> DCDC1) (with or without regulator_name) makes > boot hang with strange errors which indicate that the processor power supply is not stable. > Once a while it did even automatically reboot. In most cases there are some EXT4 errors > afterwards. I am coming closer, I think. I have now touched only the DCDC1 node name. a) with "SUDCDC1" -> "DCDC1" (bad bood): regulator_of_get_init_node() returns the child node Then: [ 0.666962] act8865 0-005a: Looking up vp1-supply from device tree [ 0.673191] DCDC1: supplied by vcc_33v [ 0.727070] DCDC1: Bringing 1200000uV into 1100000-1100000uV [ 0.739398] DCDC1: 1100 mV, enabled b) without patch/series or reverted (good boot): regulator_of_get_init_node() returns NULL Then: [ 1.016487] DCDC1: at 1200 mV, enabled [ 1.020578] act8865 0-005a: Looking up vp1-supply from device tree [ 1.026917] DCDC1: supplied by vcc_33v So at least for my board the patched series seems to reduce DCDC1 voltage to 1.1V which may trigger the boot and stability problems on my board while it is fine for yours. This could explain the hardware dependency. Now I have no data sheets or information which voltages are the right ones and where the 1200mV come from (most likely some default programmed into the PMU chip). And the issue seems to be that without matching the node names the voltages in the device tree may have been ignored completely all the time... Now it sets up voltages, which should happen. But different ones for my board which breaks boot. Finally I did risk (I have no replacement CI20 board and they are no longer on sale... RS part# was 125-3305 Mouser 456-VL-62851) to run a test with rename to "DCDC1" but changing the voltage to 1200mV. And this version boots. Still without WiFi/Bluetooth but that may be related to missing rename of the other regulators. So I tried renaming all regulators as by your [PATCH 2/9], and now I see something from WiFi (haven't installed firmware yet) and the Bluetooth chip: [ 1.977876] mmc1: new high speed SDIO card at address 0001 [ 11.341994] Bluetooth: hci0: BCM: chip id 62 [ 11.348811] Bluetooth: hci0: BCM: features 0x0f [ 11.376698] Bluetooth: hci0: BCM4330B1 [ 11.380662] Bluetooth: hci0: BCM4330B1 (002.001.003) build 0000 [ 11.392053] Bluetooth: hci0: BCM4330B1 'brcm/BCM4330B1.hcd' Patch [ 12.145330] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac4330-sdio.img,ci20.bin failed with error -2 [ 12.208001] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac4330-sdio.clm_blob failed with error -2 Unfortunatley systemd bailed out starting Bluetooth service but failed to provide a login: In summary it looks like a potential fix could be to replace the DCDC1 min/max range by 1.0 - 1.2V instead of 1.1 - 1.1V but we need deeper understanding first. Usually this has something to do with dynamic voltage scaling depending on processor clock and lower voltages are only allowed for lower frequencies but max. clock requires the highest possible voltage. AFAIK we have no cpufreq integrated and therefore always run at max. speed. BR, Nikolaus PS: here is what I read back from the regulator voltages (for DCDC1 min/max = 1.2V): root@letux:~# cat /sys/kernel/debug/regulator/regulator_summary regulator use open bypass opmode voltage current min max --------------------------------------------------------------------------------------- regulator-dummy 1 0 0 unknown 0mV 0mA 0mV 0mV eth0_power 1 1 0 unknown 3300mV 0mA 3300mV 3300mV 16000000.dm9000-vcc 1 0mA 0mV 0mV otg_power 0 0 0 unknown 5000mV 0mA 5000mV 5000mV vcc_33v 4 9 0 unknown 3300mV 0mA 3300mV 3300mV 13450000.mmc-vqmmc 1 0mA 0mV 0mV 13450000.mmc-vmmc 1 0mA 3300mV 3400mV DCDC1 1 0 0 standby 1200mV 0mA 1200mV 1200mV DCDC2 0 0 0 standby 1500mV 0mA 0mV 0mV DCDC3 0 0 0 unknown 3300mV 0mA 0mV 0mV LDO5 0 0 0 unknown 2500mV 0mA 0mV 0mV LDO6 0 0 0 normal 1800mV 0mA 1800mV 1800mV LDO7 0 0 0 unknown 3300mV 0mA 0mV 0mV LDO8 0 0 0 unknown 3300mV 0mA 0mV 0mV SUDCDC_REG4 0 0 0 normal 5000mV 0mA 0mV 0mV LDO_REG9 1 0 0 unknown 3300mV 0mA 3300mV 3300mV LDO_REG10 1 0 0 unknown 1200mV 0mA 1200mV 1200mV bt_power 0 0 0 unknown 3300mV 0mA 3300mV 3300mV root@letux:~# This matches device tree except DCDC1, LDO7 and LDO8 (camera).