• Matt Redfearn's avatar
    MIPS: pm-cps: Block system suspend when a JTAG probe is present · b2ed33a8
    Matt Redfearn authored
    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: default avatarEd Blake <ed.blake@sondrel.com>
    Signed-off-by: default avatarMatt 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: default avatarJames Hogan <jhogan@kernel.org>
    b2ed33a8
pm-cps.c 21.2 KB