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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: Marc 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: Thomas Gleixner <tglx@linutronix.de>
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