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iommu/rockchip: Clear stale page faults before enabling stall

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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 <gahing@gahingwoo.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Jiaxing Hu
2026-07-18 15:11:43 +12:00
committed by Will Deacon
parent 841363ebb5
commit b10d5920ca
1 changed files with 13 additions and 0 deletions
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13
drivers/iommu/rockchip-iommu.c
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@@ -418,6 +418,19 @@ 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,