• Marc Zyngier's avatar
    clocksource/arm_arch_timer: Force per-CPU interrupt to be level-triggered · f005bd7e
    Marc Zyngier authored
    The ARM architected timer produces level-triggered interrupts (this
    is mandated by the architecture). Unfortunately, a number of
    device-trees get this wrong, and expose an edge-triggered interrupt.
    
    Until now, this wasn't too much an issue, as the programming of the
    trigger would fail (the corresponding PPI cannot be reconfigured),
    and the kernel would be happy with this. But we're about to change
    this, and trust DT a lot if the driver doesn't provide its own
    trigger information. In that context, the timer breaks badly.
    
    While we do need to fix the DTs, there is also some userspace out
    there (kvmtool) that generates the same kind of broken DT on the
    fly, and that will completely break with newer kernels.
    
    As a safety measure, and to keep buggy software alive as well as
    buying us some time to fix DTs all over the place, let's check
    what trigger configuration has been given us by the firmware.
    If this is not a level configuration, then we know that the
    DT/ACPI configuration is bust, and we pick some defaults which
    won't be worse than the existing setup.
    Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
    Cc: Andrew Lunn <andrew@lunn.ch>
    Cc: Liu Gang <Gang.Liu@nxp.com>
    Cc: Mark Rutland <marc.rutland@arm.com>
    Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
    Cc: Wenbin Song <Wenbin.Song@freescale.com>
    Cc: Mingkai Hu <Mingkai.Hu@freescale.com>
    Cc: Florian Fainelli <f.fainelli@gmail.com>
    Cc: Kevin Hilman <khilman@baylibre.com>
    Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
    Cc: Michal Simek <michal.simek@xilinx.com>
    Cc: Jon Hunter <jonathanh@nvidia.com>
    Cc: arm@kernel.org
    Cc: bcm-kernel-feedback-list@broadcom.com
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
    Cc: Jason Cooper <jason@lakedaemon.net>
    Cc: Ray Jui <rjui@broadcom.com>
    Cc: "Hou Zhiqiang" <B48286@freescale.com>
    Cc: Tirumalesh Chalamarla <tchalamarla@cavium.com>
    Cc: linux-samsung-soc@vger.kernel.org
    Cc: Yuan Yao <yao.yuan@nxp.com>
    Cc: Jan Glauber <jglauber@cavium.com>
    Cc: Gregory Clement <gregory.clement@free-electrons.com>
    Cc: linux-amlogic@lists.infradead.org
    Cc: soren.brinkmann@xilinx.com
    Cc: Rajesh Bhagat <rajesh.bhagat@freescale.com>
    Cc: Scott Branden <sbranden@broadcom.com>
    Cc: Duc Dang <dhdang@apm.com>
    Cc: Kukjin Kim <kgene@kernel.org>
    Cc: Carlo Caione <carlo@caione.org>
    Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
    Link: http://lkml.kernel.org/r/1470045256-9032-2-git-send-email-marc.zyngier@arm.comSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    f005bd7e
arm_arch_timer.c 24.3 KB