In the Raspberry Pi 4 bootloader configuration, it is said:
USB_MSD_PWR_OFF_TIME
During USB mass storage boot, power to the USB ports is switched off for a short time to ensure the correct operation of USB mass storage devices. Most devices work correctly using the default setting: change this only if you have problems booting from a particular device. Setting USB_MSD_PWR_OFF_TIME=0 will prevent power to the USB ports being switched off during USB mass storage boot.
This makes it sound like:
- This option only applies when the Raspberry boots from a USB mass storage device and not SD card. I assume this refers to boot mode 0x4, USB-MSD, and not 0x1, SD CARD.
- The documentation also says:
During USB mass storage boot, power to the USB ports is switched off for a short time to ensure the correct operation of USB mass storage devices.
The mention of mass storage devices is a bit confusing, and again made me wonder if this setting is somehow only relevant for mass storage boot and not other USB devices. I set the setting to 5000 and put a little LED indicator device in the USB port. It looked like the USB ports were unpowered for 5 seconds when booting from an SD card. Is the documentation off here, and is this feature supposed to work regardless of what boot mode is used?
This came up when I was looking for ways to cut power to problematic USB cameras to power cycle them on boot.
In the Raspberry Pi 4 bootloader configuration, it is said:
This makes it sound like:
The mention of mass storage devices is a bit confusing, and again made me wonder if this setting is somehow only relevant for mass storage boot and not other USB devices. I set the setting to 5000 and put a little LED indicator device in the USB port. It looked like the USB ports were unpowered for 5 seconds when booting from an SD card. Is the documentation off here, and is this feature supposed to work regardless of what boot mode is used?
This came up when I was looking for ways to cut power to problematic USB cameras to power cycle them on boot.