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In commit44bd78dd2b("irqchip/gic-v3: Disable pseudo NMIs on MediaTek devices w/ firmware issues") we added a method for detecting MediaTek devices with broken firmware and disabled pseudo-NMI. While that worked, it didn't address the problem at a deep enough level. The fundamental issue with this broken firmware is that it's not saving and restoring several important GICR registers. The current list is believed to be: * GICR_NUM_IPRIORITYR * GICR_CTLR * GICR_ISPENDR0 * GICR_ISACTIVER0 * GICR_NSACR Pseudo-NMI didn't work because it was the only thing (currently) in the kernel that relied on the broken registers, so forcing pseudo-NMI off was an effective fix. However, it could be observed that calling system_uses_irq_prio_masking() on these systems still returned "true". That caused confusion and led to the need for commita07a594152("arm64: smp: avoid NMI IPIs with broken MediaTek FW"). It's worried that the incorrect value returned by system_uses_irq_prio_masking() on these systems will continue to confuse future developers. Let's fix the issue a little more completely by disabling IRQ priorities at a deeper level in the kernel. Once we do this we can revert some of the other bits of code dealing with this quirk. This includes a partial revert of commit44bd78dd2b("irqchip/gic-v3: Disable pseudo NMIs on MediaTek devices w/ firmware issues"). This isn't a full revert because it leaves some of the changes to the "quirks" structure around in case future code needs it. Suggested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20231107072651.v2.1.Ide945748593cffd8ff0feb9ae22b795935b944d6@changeid Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.