feat: interrupt-driven xHCI keyboard — eliminate 20ms poll latency#241
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feat: interrupt-driven xHCI keyboard — eliminate 20ms poll latency#241
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The xHCI MSI handler was disabling the GIC SPI after each interrupt and relying on a rate-limited timer poll (50 Hz / 20ms) to re-enable it. This meant every keystroke after the first waited up to 20ms+ for the next poll tick, defeating the purpose of MSI interrupts entirely. Now handle_interrupt() re-enables the SPI after draining the event ring, so the next USB event gets a real interrupt immediately. The timer poll remains as housekeeping (endpoint resets, deferred init) but no longer gates keyboard responsiveness. Changes: - Re-enable GIC SPI at end of handle_interrupt() after event drain - Remove poll % 4 rate-limiting from poll_hid_events() (every tick now) - One-shot SPI activation via SPI_ACTIVATED flag (250ms after init) - Reduce deferred doorbell re-ring from poll=300 to poll=75 - Gate procfs xhci module behind cfg(target_arch = "aarch64") - Graphics and page table performance experiments (WIP) Co-Authored-By: Ryan Breen <rbreen@gmail.com> Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
handle_interrupt()after draining the event ring, so the next USB event gets a real MSI interrupt immediately instead of waiting for a timer pollpoll % 4rate-limiting frompoll_hid_events()— was throttling to 50 Hz (20ms), now runs every tick (200 Hz / 5ms) as pure housekeepingSPI_ACTIVATEDflag at 250ms post-init (down from 1 second)cfg(target_arch = "aarch64")(fixes x86-64 build)Test plan
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