Boot firmware can leave an IOMMU bank in PAGE_FAULT_ACTIVE before the driver has configured paging:
PAGE_FAULT_ACTIVE=1 STALL_ACTIVE=0 IDLE=1 Such a bank ignores CMD_ENABLE_STALL and never reaches STALL_ACTIVE, so rk_iommu_enable_stall()'s readx_poll_timeout() spins until it times out (seen on the RK3576 NPU, whose MMUs share this poll across banks). Rather than special-casing these banks in the stall path, acknowledge the stale fault with CMD_PAGE_FAULT_DONE before enabling stall, so every bank starts from a clean state and the normal stall sequence applies to all of them. Banks without a pending fault are untouched. Signed-off-by: Jiaxing Hu <[email protected]> --- drivers/iommu/rockchip-iommu.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c index 62cd6b022..68bd55433 100644 --- a/drivers/iommu/rockchip-iommu.c +++ b/drivers/iommu/rockchip-iommu.c @@ -415,6 +415,19 @@ static int rk_iommu_enable_stall(struct rk_iommu *iommu) if (!rk_iommu_is_paging_enabled(iommu)) return 0; + /* + * Boot firmware can leave a bank in PAGE_FAULT_ACTIVE with no handler + * (PAGE_FAULT_ACTIVE & !STALL_ACTIVE & IDLE). Such a bank ignores + * CMD_ENABLE_STALL and never reaches STALL_ACTIVE, timing out the poll + * below. Acknowledge any stale fault first so every bank starts clean. + */ + for (i = 0; i < iommu->num_mmu; i++) { + if (rk_iommu_read(iommu->bases[i], RK_MMU_STATUS) & + RK_MMU_STATUS_PAGE_FAULT_ACTIVE) + writel(RK_MMU_CMD_PAGE_FAULT_DONE, + iommu->bases[i] + RK_MMU_COMMAND); + } + rk_iommu_command(iommu, RK_MMU_CMD_ENABLE_STALL); ret = readx_poll_timeout(rk_iommu_is_stall_active, iommu, val, -- 2.43.0
