On the K210, the prior stage bootloader does not clear IPIs. This presents a problem, because U-Boot up until this point assumes (with one exception) that IPIs are cleared when it starts. This series attempts to fix this in a robust manner, and fix several concurrency bugs I noticed while fixing these other areas. Heinrich previously submitted a patch addressing part of this problem in [1].
[1] https://patchwork.ozlabs.org/project/uboot/patch/20200811035648.3284-1-xypro...
Changes in v3: - Rename riscv_ipi_init_secondary_hart to dummy_pending_ipi_clear - Only compile dummy_pending_ipi_clear when SMP is enabled - Clarify XIP comment - Updated and expanded most commit messages
Changes in v2: - Use a valid bit instead of addr to validate IPIs - Make riscv_ipi_init_secondary_hart static - Remove fences after amoswaps - Set gp early with XIP - Clarify comments regarding tp
Sean Anderson (7): Revert "riscv: Clear pending interrupts before enabling IPIs" riscv: Match memory barriers between send_ipi_many and handle_ipi riscv: Use a valid bit to ignore already-pending IPIs riscv: Clear pending IPIs on initialization riscv: Consolidate fences into AMOs for available_harts_lock riscv: Ensure gp is NULL or points to valid data riscv: Add some comments to start.S
arch/riscv/cpu/cpu.c | 20 +++++++++++++ arch/riscv/cpu/start.S | 58 ++++++++++++++++++++++++++++-------- arch/riscv/include/asm/smp.h | 7 +++++ arch/riscv/lib/interrupts.c | 3 +- arch/riscv/lib/smp.c | 16 +++++++++- 5 files changed, 89 insertions(+), 15 deletions(-)