From: Midgy BALON <midgy971@gmail•com>
To: tomeu@tomeuvizoso•net, ogabbay@kernel•org, heiko@sntech•de,
robh@kernel•org, krzk+dt@kernel•org, conor+dt@kernel•org,
joro@8bytes•org, will@kernel•org
Cc: robin.murphy@arm•com, dri-devel@lists•freedesktop.org,
linux-rockchip@lists•infradead.org, devicetree@vger•kernel.org,
linux-arm-kernel@lists•infradead.org, iommu@lists•linux.dev,
linux-kernel@vger•kernel.org
Subject: [RFC PATCH v3 6/9] iommu/rockchip: Clear AUTO_GATING bit 1 on the RK356x v1 IOMMU
Date: Thu, 4 Jun 2026 13:52:52 +0000 [thread overview]
Message-ID: <20260604135255.62682-7-midgy971@gmail.com> (raw)
In-Reply-To: <20260604135255.62682-1-midgy971@gmail.com>
On the RK356x v1 IOMMU, RK_MMU_AUTO_GATING resets to 0x3. Bit 1 enables
auto clock-gating of the page-table walker, so the walker's AXI master
loses its clock between transactions; a TLB-miss page walk then never
completes and the IOMMU is left stuck (PAGING_ENABLED, never IDLE).
Clear bit 1 (keeping bit 0, the slave-port gate) once paging is enabled
so the walker keeps its clock. This is required for the RK3568 NPU MMU.
Signed-off-by: Midgy BALON <midgy971@gmail•com>
---
drivers/iommu/rockchip-iommu.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index 4da80136933c4..e3d8b6e9ca12b 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -953,6 +953,18 @@ static int rk_iommu_enable(struct rk_iommu *iommu)
ret = rk_iommu_enable_paging(iommu);
+ if (!ret) {
+ /*
+ * RK356x v1 IOMMU: RK_MMU_AUTO_GATING bit 1 enables page-walker
+ * auto clock-gating; the walker's AXI master then loses its clock
+ * between transactions and a TLB-miss page walk never completes,
+ * leaving the IOMMU stuck (PAGING_ENABLED, never IDLE). Clear
+ * bit 1 (keep bit 0, the slave-port gate) once paging is enabled.
+ */
+ for (i = 0; i < iommu->num_mmu; i++)
+ rk_iommu_write(iommu->bases[i], RK_MMU_AUTO_GATING, 0x2);
+ }
+
out_disable_stall:
rk_iommu_disable_stall(iommu);
out_disable_clocks:
--
2.39.5
next prev parent reply other threads:[~2026-06-04 13:53 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-04 13:52 [RFC PATCH v3 0/9] accel: rocket: Add RK3568 NPU support Midgy BALON
2026-06-04 13:52 ` [RFC PATCH v3 1/9] accel: rocket: Introduce per-SoC rocket_soc_data Midgy BALON
2026-06-04 13:52 ` [RFC PATCH v3 2/9] accel: rocket: Derive DMA width and core count from match data Midgy BALON
2026-06-04 13:52 ` [RFC PATCH v3 3/9] accel: rocket: Add RK3568 SoC support Midgy BALON
2026-06-04 13:52 ` [RFC PATCH v3 4/9] accel: rocket: Reset the NPU before detaching the IOMMU on timeout Midgy BALON
2026-06-04 13:52 ` [RFC PATCH v3 5/9] accel: rocket: Keep the IOMMU domain attached across jobs Midgy BALON
2026-06-04 13:52 ` Midgy BALON [this message]
2026-06-04 14:20 ` [RFC PATCH v3 6/9] iommu/rockchip: Clear AUTO_GATING bit 1 on the RK356x v1 IOMMU Tomeu Vizoso
2026-06-05 1:59 ` Chaoyi Chen
2026-06-04 13:52 ` [RFC PATCH v3 7/9] dt-bindings: npu: rockchip,rk3588-rknn-core: Add RK3568 Midgy BALON
2026-06-04 13:52 ` [RFC PATCH v3 8/9] arm64: dts: rockchip: rk356x: Add the NPU and its IOMMU Midgy BALON
2026-06-04 13:52 ` [RFC PATCH v3 9/9] arm64: dts: rockchip: rk3568-rock-3b: Enable the NPU Midgy BALON
2026-06-05 1:36 ` [RFC PATCH v3 0/9] accel: rocket: Add RK3568 NPU support Chaoyi Chen
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