Messages in this thread | ![/](/images/icornerl.gif) | | Date | Tue, 16 May 2023 15:24:18 +0200 | Subject | Re: [PATCH v2 1/5] dt-bindings: interrupt-controller: arm,gic-v3: Add quirk for Mediatek SoCs w/ broken FW | From | AngeloGioacchino Del Regno <> |
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Il 15/05/23 22:13, Douglas Anderson ha scritto: > When trying to turn on the "pseudo NMI" kernel feature in Linux, it > was discovered that all Mediatek-based Chromebooks that ever shipped > (at least ones with GICv3) had a firmware bug where they wouldn't save > certain GIC "GICR" registers properly. If a processor ever entered a > suspend/idle mode where the GICR registers lost state then they'd be > reset to their default state. > > As a result of the bug, if you try to enable "pseudo NMIs" on the > affected devices then certain interrupts will unexpectedly get > promoted to be "pseudo NMIs" and cause crashes / freezes / general > mayhem. > > ChromeOS is looking to start turning on "pseudo NMIs" in production to > make crash reports more actionable. To do so, we will release firmware > updates for at least some of the affected Mediatek Chromebooks. > However, even when we update the firmware of a Chromebook it's always > possible that a user will end up booting with old firmware. We need to > be able to detect when we're running with firmware that will crash and > burn if pseudo NMIs are enabled. > > The current plan is: > * Update the device trees of all affected Chromebooks to include the > 'mediatek,broken-save-restore-fw' property. The kernel can use this > to know not to enable certain features like "pseudo NMI". NOTE: > device trees for Chromebooks are never baked into the firmware but > are bundled with the kernel. A kernel will never be configured to > use "pseudo NMIs" and be bundled with an old device tree. > * When we get a fixed firmware for one of these Chromebooks, it will > patch the device tree to remove this property. > > For some details, you can also see the public bug > <https://issuetracker.google.com/281831288> > > Reviewed-by: Julius Werner <jwerner@chromium.org> > Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
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