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| author | Doug Berger <opendmb@gmail.com> | 2024-02-10 04:24:49 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-02-23 11:12:44 +0300 |
| commit | 659311f593188a3d6c6adcb7d9316993f9431a91 (patch) | |
| tree | 67fbd1d2bc8d228ded860ba0e5e4851ce28fa096 /drivers/irqchip | |
| parent | 783912cbce88be94ac2f9d4c256bd61e708814ce (diff) | |
| download | linux-659311f593188a3d6c6adcb7d9316993f9431a91.tar.xz | |
irqchip/irq-brcmstb-l2: Add write memory barrier before exit
commit b0344d6854d25a8b3b901c778b1728885dd99007 upstream.
It was observed on Broadcom devices that use GIC v3 architecture L1
interrupt controllers as the parent of brcmstb-l2 interrupt controllers
that the deactivation of the parent interrupt could happen before the
brcmstb-l2 deasserted its output. This would lead the GIC to reactivate the
interrupt only to find that no L2 interrupt was pending. The result was a
spurious interrupt invoking handle_bad_irq() with its associated
messaging. While this did not create a functional problem it is a waste of
cycles.
The hazard exists because the memory mapped bus writes to the brcmstb-l2
registers are buffered and the GIC v3 architecture uses a very efficient
system register write to deactivate the interrupt.
Add a write memory barrier prior to invoking chained_irq_exit() to
introduce a dsb(st) on those systems to ensure the system register write
cannot be executed until the memory mapped writes are visible to the
system.
[ florian: Added Fixes tag ]
Fixes: 7f646e92766e ("irqchip: brcmstb-l2: Add Broadcom Set Top Box Level-2 interrupt controller")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Florian Fainelli <florian.fainelli@broadcom.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240210012449.3009125-1-florian.fainelli@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/irqchip')
| -rw-r--r-- | drivers/irqchip/irq-brcmstb-l2.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/irqchip/irq-brcmstb-l2.c b/drivers/irqchip/irq-brcmstb-l2.c index 091b0fe7e324..5d4421f75b43 100644 --- a/drivers/irqchip/irq-brcmstb-l2.c +++ b/drivers/irqchip/irq-brcmstb-l2.c @@ -2,7 +2,7 @@ /* * Generic Broadcom Set Top Box Level 2 Interrupt controller driver * - * Copyright (C) 2014-2017 Broadcom + * Copyright (C) 2014-2024 Broadcom */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt @@ -113,6 +113,9 @@ static void brcmstb_l2_intc_irq_handle(struct irq_desc *desc) generic_handle_domain_irq(b->domain, irq); } while (status); out: + /* Don't ack parent before all device writes are done */ + wmb(); + chained_irq_exit(chip, desc); } |