media: rkvdec: Add RCB and SRAM support

cazou · Hans Verkuil · commit e5640dbb991c · 2026-01-21T14:43:09.000+01:00
The RCB (Rows and Cols Buffers) are a set of buffers used by other
variations of the decoder to store temporary data.

Those variation come with a dedicated SRAM area used to store those
buffers for better performances.

The buffer sizes are either the width or height of the frame being
decoded multiplied by a documented factor and can be stored either
in SRAM or RAM.
A fallback to RAM is provided if the SRAM is full (e.g.: multiple
streams are being decoded at the same time).

To manage the different kind of allocation, an enum is added to the
rkvdec_aux_buf struct to specify how the buffer was allocated, and
so, how to free it.

This commit is in preparation of other variants support.

Tested-by: Diederik de Haas &lt;didi.debian@cknow.org&gt;  # Rock 5B
Reviewed-by: Nicolas Dufresne &lt;nicolas.dufresne@collabora.com&gt;
Signed-off-by: Detlev Casanova &lt;detlev.casanova@collabora.com&gt;
Signed-off-by: Nicolas Dufresne &lt;nicolas.dufresne@collabora.com&gt;
Signed-off-by: Hans Verkuil &lt;hverkuil+cisco@kernel.org&gt;
diff --git a/drivers/media/platform/rockchip/rkvdec/Makefile b/drivers/media/platform/rockchip/rkvdec/Makefile
@@ -7,4 +7,5 @@ rockchip-vdec-y += \
 		   rkvdec-h264-common.o \
 		   rkvdec-hevc.o \
 		   rkvdec-hevc-common.o \
+		   rkvdec-rcb.o \
 		   rkvdec-vp9.o
diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-rcb.c b/drivers/media/platform/rockchip/rkvdec/rkvdec-rcb.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Rockchip video decoder Rows and Cols Buffers manager
+ *
+ * Copyright (C) 2025 Collabora, Ltd.
+ *  Detlev Casanova <detlev.casanova@collabora.com>
+ */
+
+#include "rkvdec.h"
+#include "rkvdec-rcb.h"
+
+#include <linux/iommu.h>
+#include <linux/genalloc.h>
+#include <linux/sizes.h>
+#include <linux/types.h>
+
+struct rkvdec_rcb_config {
+	struct rkvdec_aux_buf *rcb_bufs;
+	size_t rcb_count;
+};
+
+static size_t rkvdec_rcb_size(const struct rcb_size_info *size_info,
+			      unsigned int width, unsigned int height)
+{
+	return size_info->multiplier * (size_info->axis == PIC_HEIGHT ? height : width);
+}
+
+dma_addr_t rkvdec_rcb_buf_dma_addr(struct rkvdec_ctx *ctx, int id)
+{
+	return ctx->rcb_config->rcb_bufs[id].dma;
+}
+
+size_t rkvdec_rcb_buf_size(struct rkvdec_ctx *ctx, int id)
+{
+	return ctx->rcb_config->rcb_bufs[id].size;
+}
+
+int rkvdec_rcb_buf_count(struct rkvdec_ctx *ctx)
+{
+	return ctx->rcb_config->rcb_count;
+}
+
+void rkvdec_free_rcb(struct rkvdec_ctx *ctx)
+{
+	struct rkvdec_dev *dev = ctx->dev;
+	struct rkvdec_rcb_config *cfg = ctx->rcb_config;
+	unsigned long virt_addr;
+	int i;
+
+	if (!cfg)
+		return;
+
+	for (i = 0; i < cfg->rcb_count; i++) {
+		size_t rcb_size = cfg->rcb_bufs[i].size;
+
+		if (!cfg->rcb_bufs[i].cpu)
+			continue;
+
+		switch (cfg->rcb_bufs[i].type) {
+		case RKVDEC_ALLOC_SRAM:
+			virt_addr = (unsigned long)cfg->rcb_bufs[i].cpu;
+
+			if (dev->iommu_domain)
+				iommu_unmap(dev->iommu_domain, virt_addr, rcb_size);
+			gen_pool_free(dev->sram_pool, virt_addr, rcb_size);
+			break;
+		case RKVDEC_ALLOC_DMA:
+			dma_free_coherent(dev->dev,
+					  rcb_size,
+					  cfg->rcb_bufs[i].cpu,
+					  cfg->rcb_bufs[i].dma);
+			break;
+		}
+	}
+
+	if (cfg->rcb_bufs)
+		devm_kfree(dev->dev, cfg->rcb_bufs);
+
+	devm_kfree(dev->dev, cfg);
+}
+
+int rkvdec_allocate_rcb(struct rkvdec_ctx *ctx,
+			const struct rcb_size_info *size_info,
+			size_t rcb_count)
+{
+	int ret, i;
+	u32 width, height;
+	struct rkvdec_dev *rkvdec = ctx->dev;
+	struct rkvdec_rcb_config *cfg;
+
+	if (!size_info || !rcb_count) {
+		ctx->rcb_config = NULL;
+		return 0;
+	}
+
+	ctx->rcb_config = devm_kzalloc(rkvdec->dev, sizeof(*ctx->rcb_config), GFP_KERNEL);
+	if (!ctx->rcb_config)
+		return -ENOMEM;
+
+	cfg = ctx->rcb_config;
+
+	cfg->rcb_bufs = devm_kzalloc(rkvdec->dev, sizeof(*cfg->rcb_bufs) * rcb_count, GFP_KERNEL);
+	if (!cfg->rcb_bufs) {
+		ret = -ENOMEM;
+		goto err_alloc;
+	}
+
+	width = ctx->decoded_fmt.fmt.pix_mp.width;
+	height = ctx->decoded_fmt.fmt.pix_mp.height;
+
+	for (i = 0; i < rcb_count; i++) {
+		void *cpu = NULL;
+		dma_addr_t dma;
+		size_t rcb_size = rkvdec_rcb_size(&size_info[i], width, height);
+		enum rkvdec_alloc_type alloc_type = RKVDEC_ALLOC_SRAM;
+
+		/* Try allocating an SRAM buffer */
+		if (ctx->dev->sram_pool) {
+			if (rkvdec->iommu_domain)
+				rcb_size = ALIGN(rcb_size, SZ_4K);
+
+			cpu = gen_pool_dma_zalloc_align(ctx->dev->sram_pool,
+							rcb_size,
+							&dma,
+							SZ_4K);
+		}
+
+		/* If an IOMMU is used, map the SRAM address through it */
+		if (cpu && rkvdec->iommu_domain) {
+			unsigned long virt_addr = (unsigned long)cpu;
+			phys_addr_t phys_addr = dma;
+
+			ret = iommu_map(rkvdec->iommu_domain, virt_addr, phys_addr,
+					rcb_size, IOMMU_READ | IOMMU_WRITE, 0);
+			if (ret) {
+				gen_pool_free(ctx->dev->sram_pool,
+					      (unsigned long)cpu,
+					      rcb_size);
+				cpu = NULL;
+				goto ram_fallback;
+			}
+
+			/*
+			 * The registers will be configured with the virtual
+			 * address so that it goes through the IOMMU
+			 */
+			dma = virt_addr;
+		}
+
+ram_fallback:
+		/* Fallback to RAM */
+		if (!cpu) {
+			cpu = dma_alloc_coherent(ctx->dev->dev,
+						 rcb_size,
+						 &dma,
+						 GFP_KERNEL);
+			alloc_type = RKVDEC_ALLOC_DMA;
+		}
+
+		if (!cpu) {
+			ret = -ENOMEM;
+			goto err_alloc;
+		}
+
+		cfg->rcb_bufs[i].cpu = cpu;
+		cfg->rcb_bufs[i].dma = dma;
+		cfg->rcb_bufs[i].size = rcb_size;
+		cfg->rcb_bufs[i].type = alloc_type;
+
+		cfg->rcb_count += 1;
+	}
+
+	return 0;
+
+err_alloc:
+	rkvdec_free_rcb(ctx);
+
+	return ret;
+}
diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec-rcb.h b/drivers/media/platform/rockchip/rkvdec/rkvdec-rcb.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Rockchip video decoder Rows and Cols Buffers manager
+ *
+ * Copyright (C) 2025 Collabora, Ltd.
+ *  Detlev Casanova <detlev.casanova@collabora.com>
+ */
+
+#include <linux/types.h>
+
+struct rkvdec_ctx;
+
+enum rcb_axis {
+	PIC_WIDTH = 0,
+	PIC_HEIGHT = 1
+};
+
+struct rcb_size_info {
+	u8 multiplier;
+	enum rcb_axis axis;
+};
+
+int rkvdec_allocate_rcb(struct rkvdec_ctx *ctx,
+			const struct rcb_size_info *size_info,
+			size_t rcb_count);
+dma_addr_t rkvdec_rcb_buf_dma_addr(struct rkvdec_ctx *ctx, int id);
+size_t rkvdec_rcb_buf_size(struct rkvdec_ctx *ctx, int id);
+int rkvdec_rcb_buf_count(struct rkvdec_ctx *ctx);
+void rkvdec_free_rcb(struct rkvdec_ctx *ctx);
diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec.c b/drivers/media/platform/rockchip/rkvdec/rkvdec.c
@@ -10,6 +10,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/genalloc.h>
 #include <linux/interrupt.h>
 #include <linux/iommu.h>
 #include <linux/module.h>
@@ -28,6 +29,7 @@
 
 #include "rkvdec.h"
 #include "rkvdec-regs.h"
+#include "rkvdec-rcb.h"
 
 static bool rkvdec_image_fmt_match(enum rkvdec_image_fmt fmt1,
 				   enum rkvdec_image_fmt fmt2)
@@ -778,6 +780,7 @@ static int rkvdec_start_streaming(struct vb2_queue *q, unsigned int count)
 {
 	struct rkvdec_ctx *ctx = vb2_get_drv_priv(q);
 	const struct rkvdec_coded_fmt_desc *desc;
+	const struct rkvdec_variant *variant = ctx->dev->variant;
 	int ret;
 
 	if (V4L2_TYPE_IS_CAPTURE(q->type))
@@ -787,13 +790,22 @@ static int rkvdec_start_streaming(struct vb2_queue *q, unsigned int count)
 	if (WARN_ON(!desc))
 		return -EINVAL;
 
+	ret = rkvdec_allocate_rcb(ctx, variant->rcb_sizes, variant->num_rcb_sizes);
+	if (ret)
+		return ret;
+
 	if (desc->ops->start) {
 		ret = desc->ops->start(ctx);
 		if (ret)
-			return ret;
+			goto err_ops_start;
 	}
 
 	return 0;
+
+err_ops_start:
+	rkvdec_free_rcb(ctx);
+
+	return ret;
 }
 
 static void rkvdec_queue_cleanup(struct vb2_queue *vq, u32 state)
@@ -829,6 +841,8 @@ static void rkvdec_stop_streaming(struct vb2_queue *q)
 
 		if (desc->ops->stop)
 			desc->ops->stop(ctx);
+
+		rkvdec_free_rcb(ctx);
 	}
 
 	rkvdec_queue_cleanup(q, VB2_BUF_STATE_ERROR);
@@ -1345,6 +1359,10 @@ static int rkvdec_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	rkvdec->sram_pool = of_gen_pool_get(pdev->dev.of_node, "sram", 0);
+	if (!rkvdec->sram_pool && rkvdec->variant->num_rcb_sizes > 0)
+		dev_info(&pdev->dev, "No sram node, RCB will be stored in RAM\n");
+
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 100);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);
@@ -1353,7 +1371,8 @@ static int rkvdec_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_disable_runtime_pm;
 
-	if (iommu_get_domain_for_dev(&pdev->dev)) {
+	rkvdec->iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
+	if (rkvdec->iommu_domain) {
 		rkvdec->empty_domain = iommu_paging_domain_alloc(rkvdec->dev);
 
 		if (IS_ERR(rkvdec->empty_domain)) {
@@ -1367,6 +1386,10 @@ static int rkvdec_probe(struct platform_device *pdev)
 err_disable_runtime_pm:
 	pm_runtime_dont_use_autosuspend(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
+
+	if (rkvdec->sram_pool)
+		gen_pool_destroy(rkvdec->sram_pool);
+
 	return ret;
 }
 
diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec.h b/drivers/media/platform/rockchip/rkvdec/rkvdec.h
@@ -19,12 +19,14 @@
 #include <media/v4l2-ctrls.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ioctl.h>
+#include <media/v4l2-mem2mem.h>
 #include <media/videobuf2-core.h>
 #include <media/videobuf2-dma-contig.h>
 
 #define RKVDEC_QUIRK_DISABLE_QOS	BIT(0)
 
 struct rkvdec_ctx;
+struct rkvdec_rcb_config;
 
 struct rkvdec_ctrl_desc {
 	struct v4l2_ctrl_config cfg;
@@ -69,6 +71,8 @@ struct rkvdec_variant {
 	unsigned int num_regs;
 	const struct rkvdec_coded_fmt_desc *coded_fmts;
 	size_t num_coded_fmts;
+	const struct rcb_size_info *rcb_sizes;
+	size_t num_rcb_sizes;
 	unsigned int quirks;
 };
 
@@ -119,6 +123,8 @@ struct rkvdec_dev {
 	void __iomem *regs;
 	struct mutex vdev_lock; /* serializes ioctls */
 	struct delayed_work watchdog_work;
+	struct gen_pool *sram_pool;
+	struct iommu_domain *iommu_domain;
 	struct iommu_domain *empty_domain;
 	const struct rkvdec_variant *variant;
 };
@@ -131,6 +137,7 @@ struct rkvdec_ctx {
 	struct v4l2_ctrl_handler ctrl_hdl;
 	struct rkvdec_dev *dev;
 	enum rkvdec_image_fmt image_fmt;
+	struct rkvdec_rcb_config *rcb_config;
 	void *priv;
 };
 
@@ -139,10 +146,16 @@ static inline struct rkvdec_ctx *file_to_rkvdec_ctx(struct file *filp)
 	return container_of(file_to_v4l2_fh(filp), struct rkvdec_ctx, fh);
 }
 
+enum rkvdec_alloc_type {
+	RKVDEC_ALLOC_DMA  = 0,
+	RKVDEC_ALLOC_SRAM = 1,
+};
+
 struct rkvdec_aux_buf {
 	void *cpu;
 	dma_addr_t dma;
 	size_t size;
+	enum rkvdec_alloc_type type;
 };
 
 void rkvdec_run_preamble(struct rkvdec_ctx *ctx, struct rkvdec_run *run);
