linux-kernel - [PATCH 11/16] media: rockchip: rga: add iommu restore function

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Message-Id: <20251007-spu-rga3-v1-11-36ad85570402@pengutronix.de>
Date: Tue, 07 Oct 2025 10:32:04 +0200
From: Sven Püschel <s.pueschel@...gutronix.de>
To: Jacob Chen <jacob-chen@...wrt.com>, 
 Ezequiel Garcia <ezequiel@...guardiasur.com.ar>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Heiko Stuebner <heiko@...ech.de>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 devicetree@...r.kernel.org, kernel@...gutronix.de, 
 Sven Püschel <s.pueschel@...gutronix.de>
Subject: [PATCH 11/16] media: rockchip: rga: add iommu restore function

Add an iommu restore function in preparation for the rga3 addition.
This is necessary for a soft reset, as the rga3 will also reset
it's iommu paging table to 0 and disable paging.

The empty domain attach/detach to restore the iommu is copied
from the rkvdec driver.

Signed-off-by: Sven Püschel <s.pueschel@...gutronix.de>
---
 drivers/media/platform/rockchip/rga/rga.c | 24 ++++++++++++++++++++++++
 drivers/media/platform/rockchip/rga/rga.h |  7 +++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c
index cd4da01645611e5fb51ed94e09b5f1463dad72c5..0a725841b0cfa41bbc5b861b8f5ceac2452fc2b5 100644
--- a/drivers/media/platform/rockchip/rga/rga.c
+++ b/drivers/media/platform/rockchip/rga/rga.c
@@ -9,6 +9,7 @@
 #include <linux/delay.h>
 #include <linux/fs.h>
 #include <linux/interrupt.h>
+#include <linux/iommu.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/pm_runtime.h>
@@ -560,6 +561,19 @@ static const struct video_device rga_videodev = {
 	.device_caps = V4L2_CAP_VIDEO_M2M_MPLANE | V4L2_CAP_STREAMING,
 };
 
+void rga_iommu_restore(struct rockchip_rga *rga)
+{
+	if (rga->empty_domain) {
+		/*
+		 * To rewrite mapping into the attached IOMMU core, attach a new empty domain that
+		 * will program an empty table, then detach it to restore the default domain and
+		 * all cached mappings.
+		 */
+		iommu_attach_device(rga->empty_domain, rga->dev);
+		iommu_detach_device(rga->empty_domain, rga->dev);
+	}
+}
+
 static int rga_parse_dt(struct rockchip_rga *rga)
 {
 	struct reset_control *core_rst, *axi_rst, *ahb_rst;
@@ -657,6 +671,13 @@ static int rga_probe(struct platform_device *pdev)
 		goto err_put_clk;
 	}
 
+	if (iommu_get_domain_for_dev(rga->dev)) {
+		rga->empty_domain = iommu_paging_domain_alloc(rga->dev);
+
+		if (!rga->empty_domain)
+			dev_warn(rga->dev, "cannot alloc new empty domain\n");
+	}
+
 	ret = v4l2_device_register(&pdev->dev, &rga->v4l2_dev);
 	if (ret)
 		goto err_put_clk;
@@ -741,6 +762,9 @@ static void rga_remove(struct platform_device *pdev)
 	v4l2_device_unregister(&rga->v4l2_dev);
 
 	pm_runtime_disable(rga->dev);
+
+	if (rga->empty_domain)
+		iommu_domain_free(rga->empty_domain);
 }
 
 static int __maybe_unused rga_runtime_suspend(struct device *dev)
diff --git a/drivers/media/platform/rockchip/rga/rga.h b/drivers/media/platform/rockchip/rga/rga.h
index fc4805ba4e8ef7fb311f780a198ba6ba4d3aff17..e19c4c82aca5ae2056f52d525138093fbbb81af8 100644
--- a/drivers/media/platform/rockchip/rga/rga.h
+++ b/drivers/media/platform/rockchip/rga/rga.h
@@ -75,6 +75,7 @@ struct rockchip_rga {
 	void __iomem *regs;
 	struct clk_bulk_data clks[3];
 	struct rockchip_rga_version version;
+	struct iommu_domain *empty_domain;
 
 	/* vfd lock */
 	struct mutex mutex;
@@ -114,6 +115,12 @@ static inline struct rga_vb_buffer *vb_to_rga(struct vb2_v4l2_buffer *vb)
 
 struct rga_frame *rga_get_frame(struct rga_ctx *ctx, enum v4l2_buf_type type);
 
+/*
+ * This should be called in an interrupt handler to make sure no memory
+ * is mapped through the IOMMU while the empty domain is attached.
+ */
+void rga_iommu_restore(struct rockchip_rga *rga);
+
 /* RGA Buffers Manage */
 extern const struct vb2_ops rga_qops;
 

-- 
2.51.0