Merge branch 'for-v4.8/media/exynos-mfc' of git://linuxtv.org/snawrocki/samsung into patchwork

* 'for-v4.8/media/exynos-mfc' of git://linuxtv.org/snawrocki/samsung:
  media: s5p-mfc: add iommu support
  media: s5p-mfc: replace custom reserved memory handling code with generic one
  media: s5p-mfc: use generic reserved memory bindings
  of: reserved_mem: add support for using more than one region for given device
  media: set proper max seg size for devices on Exynos SoCs
  media: vb2-dma-contig: add helper for setting dma max seg size
  s5p-mfc: Fix race between s5p_mfc_probe() and s5p_mfc_open()
  s5p-mfc: Add release callback for memory region devs
  s5p-mfc: Set device name for reserved memory region devs

Documentation/devicetree/bindings/media/s5p-mfc.txt

@@ -21,15 +21,18 @@ Required properties:
   - clock-names : from common clock binding: must contain "mfc",
 		  corresponding to entry in the clocks property.
 
-  - samsung,mfc-r : Base address of the first memory bank used by MFC
-		    for DMA contiguous memory allocation and its size.
-
-  - samsung,mfc-l : Base address of the second memory bank used by MFC
-		    for DMA contiguous memory allocation and its size.
-
 Optional properties:
   - power-domains : power-domain property defined with a phandle
 			   to respective power domain.
+  - memory-region : from reserved memory binding: phandles to two reserved
+	memory regions, first is for "left" mfc memory bus interfaces,
+	second if for the "right" mfc memory bus, used when no SYSMMU
+	support is available
+
+Obsolete properties:
+  - samsung,mfc-r, samsung,mfc-l : support removed, please use memory-region
+	property instead
+
 
 Example:
 SoC specific DT entry:
@@ -43,9 +46,29 @@ mfc: codec@13400000 {
 	clock-names = "mfc";
 };
 
+Reserved memory specific DT entry for given board (see reserved memory binding
+for more information):
+
+reserved-memory {
+	#address-cells = <1>;
+	#size-cells = <1>;
+	ranges;
+
+	mfc_left: region@51000000 {
+		compatible = "shared-dma-pool";
+		no-map;
+		reg = <0x51000000 0x800000>;
+	};
+
+	mfc_right: region@43000000 {
+		compatible = "shared-dma-pool";
+		no-map;
+		reg = <0x43000000 0x800000>;
+	};
+};
+
 Board specific DT entry:
 
 codec@13400000 {
-	samsung,mfc-r = <0x43000000 0x800000>;
-	samsung,mfc-l = <0x51000000 0x800000>;
+	memory-region = <&mfc_left>, <&mfc_right>;
 };

drivers/media/platform/exynos-gsc/gsc-core.c

@@ -1124,6 +1124,7 @@ static int gsc_probe(struct platform_device *pdev)
 		goto err_m2m;
 
 	/* Initialize continious memory allocator */
+	vb2_dma_contig_set_max_seg_size(dev, DMA_BIT_MASK(32));
 	gsc->alloc_ctx = vb2_dma_contig_init_ctx(dev);
 	if (IS_ERR(gsc->alloc_ctx)) {
 		ret = PTR_ERR(gsc->alloc_ctx);
@@ -1153,6 +1154,7 @@ static int gsc_remove(struct platform_device *pdev)
 	v4l2_device_unregister(&gsc->v4l2_dev);
 
 	vb2_dma_contig_cleanup_ctx(gsc->alloc_ctx);
+	vb2_dma_contig_clear_max_seg_size(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 	gsc_clk_put(gsc);
 

drivers/media/platform/exynos4-is/fimc-core.c

@@ -1019,6 +1019,7 @@ static int fimc_probe(struct platform_device *pdev)
 	}
 
 	/* Initialize contiguous memory allocator */
+	vb2_dma_contig_set_max_seg_size(dev, DMA_BIT_MASK(32));
 	fimc->alloc_ctx = vb2_dma_contig_init_ctx(dev);
 	if (IS_ERR(fimc->alloc_ctx)) {
 		ret = PTR_ERR(fimc->alloc_ctx);
@@ -1124,6 +1125,7 @@ static int fimc_remove(struct platform_device *pdev)
 
 	fimc_unregister_capture_subdev(fimc);
 	vb2_dma_contig_cleanup_ctx(fimc->alloc_ctx);
+	vb2_dma_contig_clear_max_seg_size(&pdev->dev);
 
 	clk_disable(fimc->clock[CLK_BUS]);
 	fimc_clk_put(fimc);

drivers/media/platform/exynos4-is/fimc-is.c

@@ -847,6 +847,7 @@ static int fimc_is_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto err_pm;
 
+	vb2_dma_contig_set_max_seg_size(dev, DMA_BIT_MASK(32));
 	is->alloc_ctx = vb2_dma_contig_init_ctx(dev);
 	if (IS_ERR(is->alloc_ctx)) {
 		ret = PTR_ERR(is->alloc_ctx);
@@ -940,6 +941,7 @@ static int fimc_is_remove(struct platform_device *pdev)
 	free_irq(is->irq, is);
 	fimc_is_unregister_subdevs(is);
 	vb2_dma_contig_cleanup_ctx(is->alloc_ctx);
+	vb2_dma_contig_clear_max_seg_size(dev);
 	fimc_is_put_clocks(is);
 	fimc_is_debugfs_remove(is);
 	release_firmware(is->fw.f_w);

drivers/media/platform/exynos4-is/fimc-lite.c

@@ -1551,6 +1551,7 @@ static int fimc_lite_probe(struct platform_device *pdev)
 			goto err_sd;
 	}
 
+	vb2_dma_contig_set_max_seg_size(dev, DMA_BIT_MASK(32));
 	fimc->alloc_ctx = vb2_dma_contig_init_ctx(dev);
 	if (IS_ERR(fimc->alloc_ctx)) {
 		ret = PTR_ERR(fimc->alloc_ctx);
@@ -1652,6 +1653,7 @@ static int fimc_lite_remove(struct platform_device *pdev)
 	pm_runtime_set_suspended(dev);
 	fimc_lite_unregister_capture_subdev(fimc);
 	vb2_dma_contig_cleanup_ctx(fimc->alloc_ctx);
+	vb2_dma_contig_clear_max_seg_size(dev);
 	fimc_lite_clk_put(fimc);
 
 	dev_info(dev, "Driver unloaded\n");

drivers/media/platform/s5p-g2d/g2d.c

@@ -681,6 +681,7 @@ static int g2d_probe(struct platform_device *pdev)
 		goto put_clk_gate;
 	}
 
+	vb2_dma_contig_set_max_seg_size(&pdev->dev, DMA_BIT_MASK(32));
 	dev->alloc_ctx = vb2_dma_contig_init_ctx(&pdev->dev);
 	if (IS_ERR(dev->alloc_ctx)) {
 		ret = PTR_ERR(dev->alloc_ctx);
@@ -757,6 +758,7 @@ static int g2d_remove(struct platform_device *pdev)
 	video_unregister_device(dev->vfd);
 	v4l2_device_unregister(&dev->v4l2_dev);
 	vb2_dma_contig_cleanup_ctx(dev->alloc_ctx);
+	vb2_dma_contig_clear_max_seg_size(&pdev->dev);
 	clk_unprepare(dev->gate);
 	clk_put(dev->gate);
 	clk_unprepare(dev->clk);

drivers/media/platform/s5p-jpeg/jpeg-core.c

@@ -2843,6 +2843,7 @@ static int s5p_jpeg_probe(struct platform_device *pdev)
 		goto device_register_rollback;
 	}
 
+	vb2_dma_contig_set_max_seg_size(&pdev->dev, DMA_BIT_MASK(32));
 	jpeg->alloc_ctx = vb2_dma_contig_init_ctx(&pdev->dev);
 	if (IS_ERR(jpeg->alloc_ctx)) {
 		v4l2_err(&jpeg->v4l2_dev, "Failed to init memory allocator\n");
@@ -2942,6 +2943,7 @@ static int s5p_jpeg_remove(struct platform_device *pdev)
 	video_unregister_device(jpeg->vfd_decoder);
 	video_unregister_device(jpeg->vfd_encoder);
 	vb2_dma_contig_cleanup_ctx(jpeg->alloc_ctx);
+	vb2_dma_contig_clear_max_seg_size(&pdev->dev);
 	v4l2_m2m_release(jpeg->m2m_dev);
 	v4l2_device_unregister(&jpeg->v4l2_dev);
 

drivers/media/platform/s5p-mfc/s5p_mfc.c

@@ -22,6 +22,7 @@
 #include <media/v4l2-event.h>
 #include <linux/workqueue.h>
 #include <linux/of.h>
+#include <linux/of_reserved_mem.h>
 #include <media/videobuf2-v4l2.h>
 #include "s5p_mfc_common.h"
 #include "s5p_mfc_ctrl.h"
@@ -29,6 +30,7 @@
 #include "s5p_mfc_dec.h"
 #include "s5p_mfc_enc.h"
 #include "s5p_mfc_intr.h"
+#include "s5p_mfc_iommu.h"
 #include "s5p_mfc_opr.h"
 #include "s5p_mfc_cmd.h"
 #include "s5p_mfc_pm.h"
@@ -1043,55 +1045,94 @@ static const struct v4l2_file_operations s5p_mfc_fops = {
 	.mmap = s5p_mfc_mmap,
 };
 
-static int match_child(struct device *dev, void *data)
+/* DMA memory related helper functions */
+static void s5p_mfc_memdev_release(struct device *dev)
 {
-	if (!dev_name(dev))
-		return 0;
-	return !strcmp(dev_name(dev), (char *)data);
+	of_reserved_mem_device_release(dev);
 }
 
-static void *mfc_get_drv_data(struct platform_device *pdev);
-
-static int s5p_mfc_alloc_memdevs(struct s5p_mfc_dev *dev)
+static struct device *s5p_mfc_alloc_memdev(struct device *dev,
+					   const char *name, unsigned int idx)
 {
-	unsigned int mem_info[2] = { };
+	struct device *child;
+	int ret;
 
-	dev->mem_dev_l = devm_kzalloc(&dev->plat_dev->dev,
-			sizeof(struct device), GFP_KERNEL);
-	if (!dev->mem_dev_l) {
-		mfc_err("Not enough memory\n");
-		return -ENOMEM;
-	}
-	device_initialize(dev->mem_dev_l);
-	of_property_read_u32_array(dev->plat_dev->dev.of_node,
-			"samsung,mfc-l", mem_info, 2);
-	if (dma_declare_coherent_memory(dev->mem_dev_l, mem_info[0],
-				mem_info[0], mem_info[1],
-				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE) == 0) {
-		mfc_err("Failed to declare coherent memory for\n"
-		"MFC device\n");
-		return -ENOMEM;
+	child = devm_kzalloc(dev, sizeof(struct device), GFP_KERNEL);
+	if (!child)
+		return NULL;
+
+	device_initialize(child);
+	dev_set_name(child, "%s:%s", dev_name(dev), name);
+	child->parent = dev;
+	child->bus = dev->bus;
+	child->coherent_dma_mask = dev->coherent_dma_mask;
+	child->dma_mask = dev->dma_mask;
+	child->release = s5p_mfc_memdev_release;
+
+	if (device_add(child) == 0) {
+		ret = of_reserved_mem_device_init_by_idx(child, dev->of_node,
+							 idx);
+		if (ret == 0)
+			return child;
 	}
 
-	dev->mem_dev_r = devm_kzalloc(&dev->plat_dev->dev,
-			sizeof(struct device), GFP_KERNEL);
-	if (!dev->mem_dev_r) {
-		mfc_err("Not enough memory\n");
-		return -ENOMEM;
+	put_device(child);
+	return NULL;
+}
+
+static int s5p_mfc_configure_dma_memory(struct s5p_mfc_dev *mfc_dev)
+{
+	struct device *dev = &mfc_dev->plat_dev->dev;
+
+	/*
+	 * When IOMMU is available, we cannot use the default configuration,
+	 * because of MFC firmware requirements: address space limited to
+	 * 256M and non-zero default start address.
+	 * This is still simplified, not optimal configuration, but for now
+	 * IOMMU core doesn't allow to configure device's IOMMUs channel
+	 * separately.
+	 */
+	if (exynos_is_iommu_available(dev)) {
+		int ret = exynos_configure_iommu(dev, S5P_MFC_IOMMU_DMA_BASE,
+						 S5P_MFC_IOMMU_DMA_SIZE);
+		if (ret == 0)
+			mfc_dev->mem_dev_l = mfc_dev->mem_dev_r = dev;
+		return ret;
 	}
-	device_initialize(dev->mem_dev_r);
-	of_property_read_u32_array(dev->plat_dev->dev.of_node,
-			"samsung,mfc-r", mem_info, 2);
-	if (dma_declare_coherent_memory(dev->mem_dev_r, mem_info[0],
-				mem_info[0], mem_info[1],
-				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE) == 0) {
-		pr_err("Failed to declare coherent memory for\n"
-		"MFC device\n");
-		return -ENOMEM;
+
+	/*
+	 * Create and initialize virtual devices for accessing
+	 * reserved memory regions.
+	 */
+	mfc_dev->mem_dev_l = s5p_mfc_alloc_memdev(dev, "left",
+						  MFC_BANK1_ALLOC_CTX);
+	if (!mfc_dev->mem_dev_l)
+		return -ENODEV;
+	mfc_dev->mem_dev_r = s5p_mfc_alloc_memdev(dev, "right",
+						  MFC_BANK2_ALLOC_CTX);
+	if (!mfc_dev->mem_dev_r) {
+		device_unregister(mfc_dev->mem_dev_l);
+		return -ENODEV;
 	}
+
 	return 0;
 }
 
+static void s5p_mfc_unconfigure_dma_memory(struct s5p_mfc_dev *mfc_dev)
+{
+	struct device *dev = &mfc_dev->plat_dev->dev;
+
+	if (exynos_is_iommu_available(dev)) {
+		exynos_unconfigure_iommu(dev);
+		return;
+	}
+
+	device_unregister(mfc_dev->mem_dev_l);
+	device_unregister(mfc_dev->mem_dev_r);
+}
+
+static void *mfc_get_drv_data(struct platform_device *pdev);
+
 /* MFC probe function */
 static int s5p_mfc_probe(struct platform_device *pdev)
 {
@@ -1117,12 +1158,6 @@ static int s5p_mfc_probe(struct platform_device *pdev)
 
 	dev->variant = mfc_get_drv_data(pdev);
 
-	ret = s5p_mfc_init_pm(dev);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "failed to get mfc clock source\n");
-		return ret;
-	}
-
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 
 	dev->regs_base = devm_ioremap_resource(&pdev->dev, res);
@@ -1143,32 +1178,25 @@ static int s5p_mfc_probe(struct platform_device *pdev)
 		goto err_res;
 	}
 
-	if (pdev->dev.of_node) {
-		ret = s5p_mfc_alloc_memdevs(dev);
-		if (ret < 0)
-			goto err_res;
-	} else {
-		dev->mem_dev_l = device_find_child(&dev->plat_dev->dev,
-				"s5p-mfc-l", match_child);
-		if (!dev->mem_dev_l) {
-			mfc_err("Mem child (L) device get failed\n");
-			ret = -ENODEV;
-			goto err_res;
-		}
-		dev->mem_dev_r = device_find_child(&dev->plat_dev->dev,
-				"s5p-mfc-r", match_child);
-		if (!dev->mem_dev_r) {
-			mfc_err("Mem child (R) device get failed\n");
-			ret = -ENODEV;
-			goto err_res;
-		}
+	ret = s5p_mfc_configure_dma_memory(dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to configure DMA memory\n");
+		return ret;
 	}
 
+	ret = s5p_mfc_init_pm(dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to get mfc clock source\n");
+		return ret;
+	}
+
+	vb2_dma_contig_set_max_seg_size(dev->mem_dev_l, DMA_BIT_MASK(32));
 	dev->alloc_ctx[0] = vb2_dma_contig_init_ctx(dev->mem_dev_l);
 	if (IS_ERR(dev->alloc_ctx[0])) {
 		ret = PTR_ERR(dev->alloc_ctx[0]);
 		goto err_res;
 	}
+	vb2_dma_contig_set_max_seg_size(dev->mem_dev_r, DMA_BIT_MASK(32));
 	dev->alloc_ctx[1] = vb2_dma_contig_init_ctx(dev->mem_dev_r);
 	if (IS_ERR(dev->alloc_ctx[1])) {
 		ret = PTR_ERR(dev->alloc_ctx[1]);
@@ -1201,14 +1229,6 @@ static int s5p_mfc_probe(struct platform_device *pdev)
 	vfd->vfl_dir	= VFL_DIR_M2M;
 	snprintf(vfd->name, sizeof(vfd->name), "%s", S5P_MFC_DEC_NAME);
 	dev->vfd_dec	= vfd;
-	ret = video_register_device(vfd, VFL_TYPE_GRABBER, 0);
-	if (ret) {
-		v4l2_err(&dev->v4l2_dev, "Failed to register video device\n");
-		video_device_release(vfd);
-		goto err_dec_reg;
-	}
-	v4l2_info(&dev->v4l2_dev,
-		  "decoder registered as /dev/video%d\n", vfd->num);
 	video_set_drvdata(vfd, dev);
 
 	/* encoder */
@@ -1226,14 +1246,6 @@ static int s5p_mfc_probe(struct platform_device *pdev)
 	vfd->vfl_dir	= VFL_DIR_M2M;
 	snprintf(vfd->name, sizeof(vfd->name), "%s", S5P_MFC_ENC_NAME);
 	dev->vfd_enc	= vfd;
-	ret = video_register_device(vfd, VFL_TYPE_GRABBER, 0);
-	if (ret) {
-		v4l2_err(&dev->v4l2_dev, "Failed to register video device\n");
-		video_device_release(vfd);
-		goto err_enc_reg;
-	}
-	v4l2_info(&dev->v4l2_dev,
-		  "encoder registered as /dev/video%d\n", vfd->num);
 	video_set_drvdata(vfd, dev);
 	platform_set_drvdata(pdev, dev);
 
@@ -1250,15 +1262,34 @@ static int s5p_mfc_probe(struct platform_device *pdev)
 	s5p_mfc_init_hw_cmds(dev);
 	s5p_mfc_init_regs(dev);
 
+	/* Register decoder and encoder */
+	ret = video_register_device(dev->vfd_dec, VFL_TYPE_GRABBER, 0);
+	if (ret) {
+		v4l2_err(&dev->v4l2_dev, "Failed to register video device\n");
+		video_device_release(dev->vfd_dec);
+		goto err_dec_reg;
+	}
+	v4l2_info(&dev->v4l2_dev,
+		  "decoder registered as /dev/video%d\n", dev->vfd_dec->num);
+
+	ret = video_register_device(dev->vfd_enc, VFL_TYPE_GRABBER, 0);
+	if (ret) {
+		v4l2_err(&dev->v4l2_dev, "Failed to register video device\n");
+		video_device_release(dev->vfd_enc);
+		goto err_enc_reg;
+	}
+	v4l2_info(&dev->v4l2_dev,
+		  "encoder registered as /dev/video%d\n", dev->vfd_enc->num);
+
 	pr_debug("%s--\n", __func__);
 	return 0;
 
 /* Deinit MFC if probe had failed */
 err_enc_reg:
-	video_device_release(dev->vfd_enc);
-err_enc_alloc:
 	video_unregister_device(dev->vfd_dec);
 err_dec_reg:
+	video_device_release(dev->vfd_enc);
+err_enc_alloc:
 	video_device_release(dev->vfd_dec);
 err_dec_alloc:
 	v4l2_device_unregister(&dev->v4l2_dev);
@@ -1293,10 +1324,9 @@ static int s5p_mfc_remove(struct platform_device *pdev)
 	s5p_mfc_release_firmware(dev);
 	vb2_dma_contig_cleanup_ctx(dev->alloc_ctx[0]);
 	vb2_dma_contig_cleanup_ctx(dev->alloc_ctx[1]);
-	if (pdev->dev.of_node) {
-		put_device(dev->mem_dev_l);
-		put_device(dev->mem_dev_r);
-	}
+	s5p_mfc_unconfigure_dma_memory(dev);
+	vb2_dma_contig_clear_max_seg_size(dev->mem_dev_l);
+	vb2_dma_contig_clear_max_seg_size(dev->mem_dev_r);
 
 	s5p_mfc_final_pm(dev);
 	return 0;

drivers/media/platform/s5p-mfc/s5p_mfc_iommu.h

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2015 Samsung Electronics Co.Ltd
+ * Authors: Marek Szyprowski <m.szyprowski@samsung.com>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#ifndef S5P_MFC_IOMMU_H_
+#define S5P_MFC_IOMMU_H_
+
+#define S5P_MFC_IOMMU_DMA_BASE	0x20000000lu
+#define S5P_MFC_IOMMU_DMA_SIZE	SZ_256M
+
+#ifdef CONFIG_EXYNOS_IOMMU
+
+#include <asm/dma-iommu.h>
+
+static inline bool exynos_is_iommu_available(struct device *dev)
+{
+	return dev->archdata.iommu != NULL;
+}
+
+static inline void exynos_unconfigure_iommu(struct device *dev)
+{
+	struct dma_iommu_mapping *mapping = to_dma_iommu_mapping(dev);
+
+	arm_iommu_detach_device(dev);
+	arm_iommu_release_mapping(mapping);
+}
+
+static inline int exynos_configure_iommu(struct device *dev,
+					 unsigned int base, unsigned int size)
+{
+	struct dma_iommu_mapping *mapping = NULL;
+	int ret;
+
+	/* Disable the default mapping created by device core */
+	if (to_dma_iommu_mapping(dev))
+		exynos_unconfigure_iommu(dev);
+
+	mapping = arm_iommu_create_mapping(dev->bus, base, size);
+	if (IS_ERR(mapping)) {
+		pr_warn("Failed to create IOMMU mapping for device %s\n",
+			dev_name(dev));
+		return PTR_ERR(mapping);
+	}
+
+	ret = arm_iommu_attach_device(dev, mapping);
+	if (ret) {
+		pr_warn("Failed to attached device %s to IOMMU_mapping\n",
+				dev_name(dev));
+		arm_iommu_release_mapping(mapping);
+		return ret;
+	}
+
+	return 0;
+}
+
+#else
+
+static inline bool exynos_is_iommu_available(struct device *dev)
+{
+	return false;
+}
+
+static inline int exynos_configure_iommu(struct device *dev,
+					 unsigned int base, unsigned int size)
+{
+	return -ENOSYS;
+}
+
+static inline void exynos_unconfigure_iommu(struct device *dev) { }
+
+#endif
+
+#endif /* S5P_MFC_IOMMU_H_ */

drivers/media/platform/s5p-tv/mixer_video.c

@@ -80,6 +80,7 @@ int mxr_acquire_video(struct mxr_device *mdev,
 		goto fail;
 	}
 
+	vb2_dma_contig_set_max_seg_size(mdev->dev, DMA_BIT_MASK(32));
 	mdev->alloc_ctx = vb2_dma_contig_init_ctx(mdev->dev);
 	if (IS_ERR(mdev->alloc_ctx)) {
 		mxr_err(mdev, "could not acquire vb2 allocator\n");
@@ -152,6 +153,7 @@ void mxr_release_video(struct mxr_device *mdev)
 		kfree(mdev->output[i]);
 
 	vb2_dma_contig_cleanup_ctx(mdev->alloc_ctx);
+	vb2_dma_contig_clear_max_seg_size(mdev->dev);
 	v4l2_device_unregister(&mdev->v4l2_dev);
 }
 

drivers/media/v4l2-core/videobuf2-dma-contig.c

@@ -753,6 +753,59 @@ void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
 }
 EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
 
+/**
+ * vb2_dma_contig_set_max_seg_size() - configure DMA max segment size
+ * @dev:	device for configuring DMA parameters
+ * @size:	size of DMA max segment size to set
+ *
+ * To allow mapping the scatter-list into a single chunk in the DMA
+ * address space, the device is required to have the DMA max segment
+ * size parameter set to a value larger than the buffer size. Otherwise,
+ * the DMA-mapping subsystem will split the mapping into max segment
+ * size chunks. This function sets the DMA max segment size
+ * parameter to let DMA-mapping map a buffer as a single chunk in DMA
+ * address space.
+ * This code assumes that the DMA-mapping subsystem will merge all
+ * scatterlist segments if this is really possible (for example when
+ * an IOMMU is available and enabled).
+ * Ideally, this parameter should be set by the generic bus code, but it
+ * is left with the default 64KiB value due to historical litmiations in
+ * other subsystems (like limited USB host drivers) and there no good
+ * place to set it to the proper value.
+ * This function should be called from the drivers, which are known to
+ * operate on platforms with IOMMU and provide access to shared buffers
+ * (either USERPTR or DMABUF). This should be done before initializing
+ * videobuf2 queue.
+ */
+int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size)
+{
+	if (!dev->dma_parms) {
+		dev->dma_parms = kzalloc(sizeof(dev->dma_parms), GFP_KERNEL);
+		if (!dev->dma_parms)
+			return -ENOMEM;
+	}
+	if (dma_get_max_seg_size(dev) < size)
+		return dma_set_max_seg_size(dev, size);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size);
+
+/*
+ * vb2_dma_contig_clear_max_seg_size() - release resources for DMA parameters
+ * @dev:	device for configuring DMA parameters
+ *
+ * This function releases resources allocated to configure DMA parameters
+ * (see vb2_dma_contig_set_max_seg_size() function). It should be called from
+ * device drivers on driver remove.
+ */
+void vb2_dma_contig_clear_max_seg_size(struct device *dev)
+{
+	kfree(dev->dma_parms);
+	dev->dma_parms = NULL;
+}
+EXPORT_SYMBOL_GPL(vb2_dma_contig_clear_max_seg_size);
+
 MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 MODULE_LICENSE("GPL");

drivers/of/of_reserved_mem.c

@@ -21,6 +21,7 @@
 #include <linux/sizes.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/sort.h>
+#include <linux/slab.h>
 
 #define MAX_RESERVED_REGIONS	16
 static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
@@ -289,53 +290,95 @@ static inline struct reserved_mem *__find_rmem(struct device_node *node)
 	return NULL;
 }
 
+struct rmem_assigned_device {
+	struct device *dev;
+	struct reserved_mem *rmem;
+	struct list_head list;
+};
+
+static LIST_HEAD(of_rmem_assigned_device_list);
+static DEFINE_MUTEX(of_rmem_assigned_device_mutex);
+
 /**
- * of_reserved_mem_device_init() - assign reserved memory region to given device
+ * of_reserved_mem_device_init_by_idx() - assign reserved memory region to
+ *					  given device
+ * @dev:	Pointer to the device to configure
+ * @np:		Pointer to the device_node with 'reserved-memory' property
+ * @idx:	Index of selected region
  *
- * This function assign memory region pointed by "memory-region" device tree
- * property to the given device.
+ * This function assigns respective DMA-mapping operations based on reserved
+ * memory region specified by 'memory-region' property in @np node to the @dev
+ * device. When driver needs to use more than one reserved memory region, it
+ * should allocate child devices and initialize regions by name for each of
+ * child device.
+ *
+ * Returns error code or zero on success.
  */
-int of_reserved_mem_device_init(struct device *dev)
+int of_reserved_mem_device_init_by_idx(struct device *dev,
+				       struct device_node *np, int idx)
 {
+	struct rmem_assigned_device *rd;
+	struct device_node *target;
 	struct reserved_mem *rmem;
-	struct device_node *np;
 	int ret;
 
-	np = of_parse_phandle(dev->of_node, "memory-region", 0);
-	if (!np)
-		return -ENODEV;
+	if (!np || !dev)
+		return -EINVAL;
+
+	target = of_parse_phandle(np, "memory-region", idx);
+	if (!target)
+		return -EINVAL;
 
-	rmem = __find_rmem(np);
-	of_node_put(np);
+	rmem = __find_rmem(target);
+	of_node_put(target);
 
 	if (!rmem || !rmem->ops || !rmem->ops->device_init)
 		return -EINVAL;
 
+	rd = kmalloc(sizeof(struct rmem_assigned_device), GFP_KERNEL);
+	if (!rd)
+		return -ENOMEM;
+
 	ret = rmem->ops->device_init(rmem, dev);
-	if (ret == 0)
+	if (ret == 0) {
+		rd->dev = dev;
+		rd->rmem = rmem;
+
+		mutex_lock(&of_rmem_assigned_device_mutex);
+		list_add(&rd->list, &of_rmem_assigned_device_list);
+		mutex_unlock(&of_rmem_assigned_device_mutex);
+
 		dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
+	} else {
+		kfree(rd);
+	}
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(of_reserved_mem_device_init);
+EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_by_idx);
 
 /**
  * of_reserved_mem_device_release() - release reserved memory device structures
+ * @dev:	Pointer to the device to deconfigure
  *
  * This function releases structures allocated for memory region handling for
  * the given device.
  */
 void of_reserved_mem_device_release(struct device *dev)
 {
-	struct reserved_mem *rmem;
-	struct device_node *np;
-
-	np = of_parse_phandle(dev->of_node, "memory-region", 0);
-	if (!np)
-		return;
-
-	rmem = __find_rmem(np);
-	of_node_put(np);
+	struct rmem_assigned_device *rd;
+	struct reserved_mem *rmem = NULL;
+
+	mutex_lock(&of_rmem_assigned_device_mutex);
+	list_for_each_entry(rd, &of_rmem_assigned_device_list, list) {
+		if (rd->dev == dev) {
+			rmem = rd->rmem;
+			list_del(&rd->list);
+			kfree(rd);
+			break;
+		}
+	}
+	mutex_unlock(&of_rmem_assigned_device_mutex);
 
 	if (!rmem || !rmem->ops || !rmem->ops->device_release)
 		return;

include/linux/of_reserved_mem.h

@@ -1,7 +1,8 @@
 #ifndef __OF_RESERVED_MEM_H
 #define __OF_RESERVED_MEM_H
 
-struct device;
+#include <linux/device.h>
+
 struct of_phandle_args;
 struct reserved_mem_ops;
 
@@ -28,14 +29,17 @@ typedef int (*reservedmem_of_init_fn)(struct reserved_mem *rmem);
 	_OF_DECLARE(reservedmem, name, compat, init, reservedmem_of_init_fn)
 
 #ifdef CONFIG_OF_RESERVED_MEM
-int of_reserved_mem_device_init(struct device *dev);
+
+int of_reserved_mem_device_init_by_idx(struct device *dev,
+				       struct device_node *np, int idx);
 void of_reserved_mem_device_release(struct device *dev);
 
 void fdt_init_reserved_mem(void);
 void fdt_reserved_mem_save_node(unsigned long node, const char *uname,
 			       phys_addr_t base, phys_addr_t size);
 #else
-static inline int of_reserved_mem_device_init(struct device *dev)
+static inline int of_reserved_mem_device_init_by_idx(struct device *dev,
+					struct device_node *np, int idx)
 {
 	return -ENOSYS;
 }
@@ -46,4 +50,19 @@ static inline void fdt_reserved_mem_save_node(unsigned long node,
 		const char *uname, phys_addr_t base, phys_addr_t size) { }
 #endif
 
+/**
+ * of_reserved_mem_device_init() - assign reserved memory region to given device
+ * @dev:	Pointer to the device to configure
+ *
+ * This function assigns respective DMA-mapping operations based on the first
+ * reserved memory region specified by 'memory-region' property in device tree
+ * node of the given device.
+ *
+ * Returns error code or zero on success.
+ */
+static inline int of_reserved_mem_device_init(struct device *dev)
+{
+	return of_reserved_mem_device_init_by_idx(dev, dev->of_node, 0);
+}
+
 #endif /* __OF_RESERVED_MEM_H */

include/media/videobuf2-dma-contig.h

@@ -35,6 +35,8 @@ static inline void *vb2_dma_contig_init_ctx(struct device *dev)
 }
 
 void vb2_dma_contig_cleanup_ctx(void *alloc_ctx);
+int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size);
+void vb2_dma_contig_clear_max_seg_size(struct device *dev);
 
 extern const struct vb2_mem_ops vb2_dma_contig_memops;