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If a JTAG probe is connected to a MIPS cluster, then the CPC detects it and latches the CPC.STAT_CONF.EJTAG_PROBE bit to 1. While set, attempting to send a power-down command to a core will be blocked, and the CPC will instead send the core to clock-off state. This can interfere with systems fully entering a low power state where all cores, CM, GIC, etc are powered down. Detect that a JTAG probe is / has been connected to the cluster and block the suspend attempt. Attempting to suspend the system while a JTAG probe is connected now yields: # echo mem > /sys/power/state [ 11.654000] PM: Syncing filesystems ... done. [ 11.658000] JTAG probe is connected - abort suspend -sh: echo: write error: Operation not permitted # To restore suspend, the JTAG probe should be disconnected or put into quiescent state. Platform code can then clear the CPC.STAT_CONF.EJTAG_PROBE bit. Reported-by: Ed Blake <ed.blake@sondrel.com> Signed-off-by: Matt Redfearn <matt.redfearn@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Burton <paul.burton@mips.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/18641/ Signed-off-by: James Hogan <jhogan@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.