1 files changed, 55 insertions, 33 deletions

diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index 5361197f3e57..863f658a3fa1 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
@@ -21,11 +21,6 @@
 #include <media/videobuf2-dma-contig.h>
 #include <media/videobuf2-memops.h>
 
-struct vb2_dc_conf {
-	struct device		*dev;
-	struct dma_attrs	attrs;
-};
-
 struct vb2_dc_buf {
 	struct device			*dev;
 	void				*vaddr;
@@ -140,18 +135,18 @@ static void vb2_dc_put(void *buf_priv)
 	kfree(buf);
 }
 
-static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size,
-			  enum dma_data_direction dma_dir, gfp_t gfp_flags)
+static void *vb2_dc_alloc(struct device *dev, const struct dma_attrs *attrs,
+			  unsigned long size, enum dma_data_direction dma_dir,
+			  gfp_t gfp_flags)
 {
-	struct vb2_dc_conf *conf = alloc_ctx;
-	struct device *dev = conf->dev;
 	struct vb2_dc_buf *buf;
 
 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
 	if (!buf)
 		return ERR_PTR(-ENOMEM);
 
-	buf->attrs = conf->attrs;
+	if (attrs)
+		buf->attrs = *attrs;
 	buf->cookie = dma_alloc_attrs(dev, size, &buf->dma_addr,
 					GFP_KERNEL | gfp_flags, &buf->attrs);
 	if (!buf->cookie) {
@@ -478,10 +473,9 @@ static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn
 }
 #endif
 
-static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
+static void *vb2_dc_get_userptr(struct device *dev, unsigned long vaddr,
 	unsigned long size, enum dma_data_direction dma_dir)
 {
-	struct vb2_dc_conf *conf = alloc_ctx;
 	struct vb2_dc_buf *buf;
 	struct frame_vector *vec;
 	unsigned long offset;
@@ -509,7 +503,7 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 	if (!buf)
 		return ERR_PTR(-ENOMEM);
 
-	buf->dev = conf->dev;
+	buf->dev = dev;
 	buf->dma_dir = dma_dir;
 
 	offset = vaddr & ~PAGE_MASK;
@@ -676,10 +670,9 @@ static void vb2_dc_detach_dmabuf(void *mem_priv)
 	kfree(buf);
 }
 
-static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
+static void *vb2_dc_attach_dmabuf(struct device *dev, struct dma_buf *dbuf,
 	unsigned long size, enum dma_data_direction dma_dir)
 {
-	struct vb2_dc_conf *conf = alloc_ctx;
 	struct vb2_dc_buf *buf;
 	struct dma_buf_attachment *dba;
 
@@ -690,7 +683,7 @@ static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 	if (!buf)
 		return ERR_PTR(-ENOMEM);
 
-	buf->dev = conf->dev;
+	buf->dev = dev;
 	/* create attachment for the dmabuf with the user device */
 	dba = dma_buf_attach(dbuf, buf->dev);
 	if (IS_ERR(dba)) {
@@ -729,29 +722,58 @@ const struct vb2_mem_ops vb2_dma_contig_memops = {
 };
 EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
 
-void *vb2_dma_contig_init_ctx_attrs(struct device *dev,
-				    struct dma_attrs *attrs)
+/**
+ * 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)
 {
-	struct vb2_dc_conf *conf;
-
-	conf = kzalloc(sizeof *conf, GFP_KERNEL);
-	if (!conf)
-		return ERR_PTR(-ENOMEM);
-
-	conf->dev = dev;
-	if (attrs)
-		conf->attrs = *attrs;
+	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 conf;
+	return 0;
 }
-EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx_attrs);
+EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size);
 
-void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
+/*
+ * 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)
 {
-	if (!IS_ERR_OR_NULL(alloc_ctx))
-		kfree(alloc_ctx);
+	kfree(dev->dma_parms);
+	dev->dma_parms = NULL;
 }
-EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
+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>");