Improved bcm2836/7 IRQ handling #6359
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Interrupts are dispatched round-robin but doing so trampled FIQ routing. Taking a FIQ on a core without a handler installed is fatal. Only modify bits 1:0 which are the IRQ route bits. Signed-off-by: Jonathan Bell <[email protected]>
BCM2836 with Cortex-A7 cores has almost the same ARM_LOCAL interrupt routing logic as BCM2837, so relax the compile guard to CONFIG_SMP not CONFIG_ARM64. Signed-off-by: Jonathan Bell <[email protected]>
Also declare as static inline, as they should be. Signed-off-by: Jonathan Bell <[email protected]>
The ARM64 architecture uses qspinlock which has a fast and slow path. This isn't ideal for all claimers of a lock operating in interrupt context. Add a ticket-based lock similar to the armv6/7 implementation. Based on an upstream patch that was abandoned in favour of qspinlock. Link: https://patchwork.kernel.org/project/linux-arm-kernel/patch/[email protected]/ Signed-off-by: Jonathan Bell <[email protected]>
Warning on normal behaviour isn't sensible and is spammy. Demote to info. Signed-off-by: Jonathan Bell <[email protected]>
The local spinlock protects the handlers from racing against each other on separate cores, hard IRQs don't preempt each other, and disabling/enabling the interrupt is more expensive than letting the fake FIQ contend the spinlock. So turn local_fiq_en/disable into no-ops. Signed-off-by: Jonathan Bell <[email protected]>
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This is exciting! I imagine this might help with the |
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At this stage it's more likely to just permute the set of errors you get. There's no guaranteed maximum interrupt latency with this patch series. |
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First phase of preparing to add platform FIQ support for armv8. Catch some low-hanging fruit first.
Posting as a PR to get autobuilds for all affected platforms (Pi 0 through 3). Only merge if you're feeling brave...