Hi, On Wed, May 31, 2023 at 6:40 AM Sasha Levin <sashal@xxxxxxxxxx> wrote: > > From: Douglas Anderson <dianders@xxxxxxxxxxxx> > > [ Upstream commit 44bd78dd2b8897f59b7e3963f088caadb7e4f047 ] > > Some Chromebooks with Mediatek SoCs have a problem where the firmware > doesn't properly save/restore certain GICR registers. Newer > Chromebooks should fix this issue and we may be able to do firmware > updates for old Chromebooks. At the moment, the only known issue with > these Chromebooks is that we can't enable "pseudo NMIs" since the > priority register can be lost. Enabling "pseudo NMIs" on Chromebooks > with the problematic firmware causes crashes and freezes. > > Let's detect devices with this problem and then disable "pseudo NMIs" > on them. We'll detect the problem by looking for the presence of the > "mediatek,broken-save-restore-fw" property in the GIC device tree > node. Any devices with fixed firmware will not have this property. > > Our detection plan works because we never bake a Chromebook's device > tree into firmware. Instead, device trees are always bundled with the > kernel. We'll update the device trees of all affected Chromebooks and > then we'll never enable "pseudo NMI" on a kernel that is bundled with > old device trees. When a firmware update is shipped that fixes this > issue it will know to patch the device tree to remove the property. > > In order to make this work, the quick detection mechanism of the GICv3 > code is extended to be able to look for properties in addition to > looking at "compatible". > > Reviewed-by: Julius Werner <jwerner@xxxxxxxxxxxx> > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > Link: https://lore.kernel.org/r/20230515131353.v2.2.I88dc0a0eb1d9d537de61604cd8994ecc55c0cac1@changeid > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > --- > drivers/irqchip/irq-gic-common.c | 8 ++++++-- > drivers/irqchip/irq-gic-common.h | 1 + > drivers/irqchip/irq-gic-v3.c | 20 ++++++++++++++++++++ > 3 files changed, 27 insertions(+), 2 deletions(-) Please delay picking this across all stable versions unless until you can also get Marc's fix: https://lore.kernel.org/r/168544149933.404.717399647227994720.tip-bot2@tip-bot2 -Doug
