Date: Fri, 19 Aug 2016 06:13:20 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-arm@FreeBSD.org Subject: [Bug 211979] On Raspberry Pi, GPIO output pins retain state on halt Message-ID: <bug-211979-7@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D211979 Bug ID: 211979 Summary: On Raspberry Pi, GPIO output pins retain state on halt Product: Base System Version: 11.0-RC1 Hardware: arm URL: http://mrp3.com OS: Any Status: New Severity: Affects Some People Priority: --- Component: arm Assignee: freebsd-arm@FreeBSD.org Reporter: bobf@mrp3.com Running FreeBSD 11.0 RC1 on a Raspbery Pi model 1 'B' When the Raspberry Pi shuts down, the pins that were selected as outputs ap= pear to retain their former state, rather than being disabled (or converted to inputs) on shutdown. This makes it difficult for a particular add-on board (the ATX-Raspi) to detect that the system has halted. As an example, the ATX-Raspi board configures one GPIO as an input, and ano= ther as an output, setting the output level to a '1' state when the helper script starts. When the script detects a shutdown or reboot condition, it executes the appropriate command on the Raspberry Pi to either shut down or reboot. This web site explains how the board works: http://hackaday.com/2013/05/19/atx-raspi-is-a-smart-power-source-for-raspbe= rry-pi/ On system halt, however, the GPIO output pin is still configured as an outp= ut with a high level. So the system never powers off, since the ATX Raspi boa= rd thinks it's still shutting down. To demonstrate it was doing this, I force= d a reboot by pressing a key on the serial console. The reboot apparently did a reset all of the GPIO pins, causing the external board to 'detect' a power down, and it then shut down the power within a few seconds [as it is suppos= ed to do]. Unfortunately this workaround isn't acceptable. This board was originally designed to work with a Linux operating system running on the Raspberry Pi. The only problem here appears to be that the = GPIO pins are not reset on halt. It may be possible to make this a kernel option that could be programmed via the /boot configuration files, in case resetti= ng them on halt would have any kind of negative impact. Since the Raspberry Pi has no ATX or ACPI interface available to shut down = the power programatically, an external board like the ATX Raspi needs some way = to easily determine that it is 'safe' to power off the Raspberry Pi. Resetting all of the GPIO pins (or making all of them input pins) on halt would make = this work. --=20 You are receiving this mail because: You are the assignee for the bug.=
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