clean up dma_declare_coherent_memory calling conventions

clean up dma_declare_coherent_memory calling conventions

[Christoph Hellwig]

Remove various unused flags, and return a reasonable error code.

[PATCH 1/2] dma-coherent: remove the DMA_MEMORY_INCLUDES_CHILDREN flag

[Christoph Hellwig]

This flag was never implemented or used.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 Documentation/DMA-API.txt     | 4 ----
 drivers/base/dma-coherent.c   | 2 --
 drivers/char/virtio_console.c | 3 ---
 include/linux/dma-mapping.h   | 3 +--
 4 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 6b20128fab8a..03072bc7ff74 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -524,10 +524,6 @@ dma_alloc_coherent() be addressable using read()/write()/memcpy_toio() etc.
 
 One or both of these flags must be present.
 
-DMA_MEMORY_INCLUDES_CHILDREN - make the declared memory be allocated by
-dma_alloc_coherent of any child devices of this one (for memory residing
-on a bridge).
-
 DMA_MEMORY_EXCLUSIVE - only allocate memory from the declared regions. 
 Do not allow dma_alloc_coherent() to fall back to system memory when
 it's out of memory in the declared region.
diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index 2ae24c28e70c..e70e33d5c902 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -109,8 +109,6 @@ static int dma_assign_coherent_memory(struct device *dev,
 		return -EBUSY;
 
 	dev->dma_mem = mem;
-	/* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
-
 	return 0;
 }
 
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index ad843eb02ae7..48e86ce9fac8 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -451,9 +451,6 @@ static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size,
 		 * device is created by remoteproc, the DMA memory is
 		 * associated with the grandparent device:
 		 * vdev => rproc => platform-dev.
-		 * The code here would have been less quirky if
-		 * DMA_MEMORY_INCLUDES_CHILDREN had been supported
-		 * in dma-coherent.c
 		 */
 		if (!vq->vdev->dev.parent || !vq->vdev->dev.parent->parent)
 			goto free_buf;
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 843ab866e0f4..fb66fe98e61d 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -685,8 +685,7 @@ static inline int dma_get_cache_alignment(void)
 /* flags for the coherent memory api */
 #define	DMA_MEMORY_MAP			0x01
 #define DMA_MEMORY_IO			0x02
-#define DMA_MEMORY_INCLUDES_CHILDREN	0x04
-#define DMA_MEMORY_EXCLUSIVE		0x08
+#define DMA_MEMORY_EXCLUSIVE		0x04
 
 #ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT
 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
-- 
2.11.0

[PATCH 2/2] dma-coherent: remove the DMA_MEMORY_MAP and DMA_MEMORY_IO flags

[Christoph Hellwig]

DMA_MEMORY_IO was never used in the tree, so remove it.  That means there is
no need for the DMA_MEMORY_MAP flag either now, so remove it as well and
change dma_declare_coherent_memory to return a normal errno value.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 Documentation/DMA-API.txt                          | 19 ---------
 arch/arm/mach-imx/mach-imx27_visstrim_m10.c        | 43 +++++++-------------
 arch/arm/mach-imx/mach-mx31moboard.c               | 12 +++---
 arch/sh/drivers/pci/fixups-dreamcast.c             |  3 +-
 drivers/base/dma-coherent.c                        | 46 +++++++---------------
 drivers/base/dma-mapping.c                         |  7 +---
 .../platform/soc_camera/sh_mobile_ceu_camera.c     |  5 +--
 drivers/scsi/NCR_Q720.c                            |  3 +-
 drivers/usb/host/ohci-sm501.c                      |  6 +--
 drivers/usb/host/ohci-tmio.c                       |  9 ++---
 include/linux/dma-mapping.h                        |  6 +--
 11 files changed, 49 insertions(+), 110 deletions(-)

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 03072bc7ff74..d464530c0ada 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -516,29 +516,10 @@ size is the size of the area (must be multiples of PAGE_SIZE).
 
 flags can be ORed together and are:
 
-DMA_MEMORY_MAP - request that the memory returned from
-dma_alloc_coherent() be directly writable.
-
-DMA_MEMORY_IO - request that the memory returned from
-dma_alloc_coherent() be addressable using read()/write()/memcpy_toio() etc.
-
-One or both of these flags must be present.
-
 DMA_MEMORY_EXCLUSIVE - only allocate memory from the declared regions. 
 Do not allow dma_alloc_coherent() to fall back to system memory when
 it's out of memory in the declared region.
 
-The return value will be either DMA_MEMORY_MAP or DMA_MEMORY_IO and
-must correspond to a passed in flag (i.e. no returning DMA_MEMORY_IO
-if only DMA_MEMORY_MAP were passed in) for success or zero for
-failure.
-
-Note, for DMA_MEMORY_IO returns, all subsequent memory returned by
-dma_alloc_coherent() may no longer be accessed directly, but instead
-must be accessed using the correct bus functions.  If your driver
-isn't prepared to handle this contingency, it should not specify
-DMA_MEMORY_IO in the input flags.
-
 As a simplification for the platforms, only *one* such region of
 memory may be declared per device.
 
diff --git a/arch/arm/mach-imx/mach-imx27_visstrim_m10.c b/arch/arm/mach-imx/mach-imx27_visstrim_m10.c
index dd75a4756761..c2818af18c55 100644
--- a/arch/arm/mach-imx/mach-imx27_visstrim_m10.c
+++ b/arch/arm/mach-imx/mach-imx27_visstrim_m10.c
@@ -245,7 +245,6 @@ static phys_addr_t mx2_camera_base __initdata;
 static void __init visstrim_analog_camera_init(void)
 {
 	struct platform_device *pdev;
-	int dma;
 
 	gpio_set_value(TVP5150_PWDN, 1);
 	ndelay(1);
@@ -258,12 +257,9 @@ static void __init visstrim_analog_camera_init(void)
 	if (IS_ERR(pdev))
 		return;
 
-	dma = dma_declare_coherent_memory(&pdev->dev,
-				mx2_camera_base, mx2_camera_base,
-				MX2_CAMERA_BUF_SIZE,
-				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
-		return;
+	dma_declare_coherent_memory(&pdev->dev, mx2_camera_base,
+				    mx2_camera_base, MX2_CAMERA_BUF_SIZE,
+				    DMA_MEMORY_EXCLUSIVE);
 }
 
 static void __init visstrim_reserve(void)
@@ -444,16 +440,13 @@ static const struct imx_ssi_platform_data visstrim_m10_ssi_pdata __initconst = {
 static void __init visstrim_coda_init(void)
 {
 	struct platform_device *pdev;
-	int dma;
 
 	pdev = imx27_add_coda();
-	dma = dma_declare_coherent_memory(&pdev->dev,
-					  mx2_camera_base + MX2_CAMERA_BUF_SIZE,
-					  mx2_camera_base + MX2_CAMERA_BUF_SIZE,
-					  MX2_CAMERA_BUF_SIZE,
-					  DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
-		return;
+	dma_declare_coherent_memory(&pdev->dev,
+				    mx2_camera_base + MX2_CAMERA_BUF_SIZE,
+				    mx2_camera_base + MX2_CAMERA_BUF_SIZE,
+				    MX2_CAMERA_BUF_SIZE,
+				    DMA_MEMORY_EXCLUSIVE);
 }
 
 /* DMA deinterlace */
@@ -466,24 +459,20 @@ static void __init visstrim_deinterlace_init(void)
 {
 	int ret = -ENOMEM;
 	struct platform_device *pdev = &visstrim_deinterlace;
-	int dma;
 
 	ret = platform_device_register(pdev);
 
-	dma = dma_declare_coherent_memory(&pdev->dev,
-					  mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
-					  mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
-					  MX2_CAMERA_BUF_SIZE,
-					  DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
-		return;
+	dma_declare_coherent_memory(&pdev->dev,
+				    mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
+				    mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
+				    MX2_CAMERA_BUF_SIZE,
+				    DMA_MEMORY_EXCLUSIVE);
 }
 
 /* Emma-PrP for format conversion */
 static void __init visstrim_emmaprp_init(void)
 {
 	struct platform_device *pdev;
-	int dma;
 
 	pdev = imx27_add_mx2_emmaprp();
 	if (IS_ERR(pdev))
@@ -493,12 +482,10 @@ static void __init visstrim_emmaprp_init(void)
 	 * Use the same memory area as the analog camera since both
 	 * devices are, by nature, exclusive.
 	 */
-	dma = dma_declare_coherent_memory(&pdev->dev,
+	dma_declare_coherent_memory(&pdev->dev,
 				mx2_camera_base, mx2_camera_base,
 				MX2_CAMERA_BUF_SIZE,
-				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
-		pr_err("Failed to declare memory for emmaprp\n");
+				DMA_MEMORY_EXCLUSIVE);
 }
 
 /* Audio */
diff --git a/arch/arm/mach-imx/mach-mx31moboard.c b/arch/arm/mach-imx/mach-mx31moboard.c
index bde9a9af6714..3cd030960c98 100644
--- a/arch/arm/mach-imx/mach-mx31moboard.c
+++ b/arch/arm/mach-imx/mach-mx31moboard.c
@@ -475,7 +475,7 @@ static phys_addr_t mx3_camera_base __initdata;
 
 static int __init mx31moboard_init_cam(void)
 {
-	int dma, ret = -ENOMEM;
+	int dma, ret;
 	struct platform_device *pdev;
 
 	imx31_add_ipu_core();
@@ -484,11 +484,11 @@ static int __init mx31moboard_init_cam(void)
 	if (IS_ERR(pdev))
 		return PTR_ERR(pdev);
 
-	dma = dma_declare_coherent_memory(&pdev->dev,
-					mx3_camera_base, mx3_camera_base,
-					MX3_CAMERA_BUF_SIZE,
-					DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
+	ret = dma_declare_coherent_memory(&pdev->dev,
+					  mx3_camera_base, mx3_camera_base,
+					  MX3_CAMERA_BUF_SIZE,
+					  DMA_MEMORY_EXCLUSIVE);
+	if (ret)
 		goto err;
 
 	ret = platform_device_add(pdev);
diff --git a/arch/sh/drivers/pci/fixups-dreamcast.c b/arch/sh/drivers/pci/fixups-dreamcast.c
index 1d1c5a227e50..c931d5872ffe 100644
--- a/arch/sh/drivers/pci/fixups-dreamcast.c
+++ b/arch/sh/drivers/pci/fixups-dreamcast.c
@@ -63,11 +63,10 @@ static void gapspci_fixup_resources(struct pci_dev *dev)
 		res.end = GAPSPCI_DMA_BASE + GAPSPCI_DMA_SIZE - 1;
 		res.flags = IORESOURCE_MEM;
 		pcibios_resource_to_bus(dev->bus, &region, &res);
-		BUG_ON(!dma_declare_coherent_memory(&dev->dev,
+		BUG_ON(dma_declare_coherent_memory(&dev->dev,
 						res.start,
 						region.start,
 						resource_size(&res),
-						DMA_MEMORY_MAP |
 						DMA_MEMORY_EXCLUSIVE));
 		break;
 	default:
diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index e70e33d5c902..bc1a4112429c 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -46,15 +46,10 @@ static bool dma_init_coherent_memory(
 	int pages = size >> PAGE_SHIFT;
 	int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
 
-	if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
-		goto out;
 	if (!size)
 		goto out;
 
-	if (flags & DMA_MEMORY_MAP)
-		mem_base = memremap(phys_addr, size, MEMREMAP_WC);
-	else
-		mem_base = ioremap(phys_addr, size);
+	mem_base = memremap(phys_addr, size, MEMREMAP_WC);
 	if (!mem_base)
 		goto out;
 
@@ -77,12 +72,8 @@ static bool dma_init_coherent_memory(
 
 out:
 	kfree(dma_mem);
-	if (mem_base) {
-		if (flags & DMA_MEMORY_MAP)
-			memunmap(mem_base);
-		else
-			iounmap(mem_base);
-	}
+	if (mem_base)
+		memunmap(mem_base);
 	return false;
 }
 
@@ -91,10 +82,7 @@ static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
 	if (!mem)
 		return;
 
-	if (mem->flags & DMA_MEMORY_MAP)
-		memunmap(mem->virt_base);
-	else
-		iounmap(mem->virt_base);
+	memunmap(mem->virt_base);
 	kfree(mem->bitmap);
 	kfree(mem);
 }
@@ -116,16 +104,16 @@ int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 				dma_addr_t device_addr, size_t size, int flags)
 {
 	struct dma_coherent_mem *mem;
+	int ret;
 
-	if (!dma_init_coherent_memory(phys_addr, device_addr, size, flags,
-				      &mem))
-		return 0;
-
-	if (dma_assign_coherent_memory(dev, mem) == 0)
-		return flags & DMA_MEMORY_MAP ? DMA_MEMORY_MAP : DMA_MEMORY_IO;
+	ret = dma_init_coherent_memory(phys_addr, device_addr, size, flags, &mem);
+	if (ret)
+		return ret;
 
-	dma_release_coherent_memory(mem);
-	return 0;
+	ret = dma_assign_coherent_memory(dev, mem);
+	if (ret)
+		dma_release_coherent_memory(mem);
+	return ret;
 }
 EXPORT_SYMBOL(dma_declare_coherent_memory);
 
@@ -185,7 +173,6 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
 	int order = get_order(size);
 	unsigned long flags;
 	int pageno;
-	int dma_memory_map;
 
 	if (!mem)
 		return 0;
@@ -205,13 +192,8 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
 	 */
 	*dma_handle = dma_get_device_base(dev, mem) + (pageno << PAGE_SHIFT);
 	*ret = mem->virt_base + (pageno << PAGE_SHIFT);
-	dma_memory_map = (mem->flags & DMA_MEMORY_MAP);
 	spin_unlock_irqrestore(&mem->spinlock, flags);
-	if (dma_memory_map)
-		memset(*ret, 0, size);
-	else
-		memset_io(*ret, 0, size);
-
+	memset(*ret, 0, size);
 	return 1;
 
 err:
@@ -312,7 +294,7 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
 
 	if (!mem &&
 	    !dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
-				      DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
+				      DMA_MEMORY_EXCLUSIVE,
 				      &mem)) {
 		pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
 			&rmem->base, (unsigned long)rmem->size / SZ_1M);
diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
index 10e7c022e8cf..b96bfffd314e 100644
--- a/drivers/base/dma-mapping.c
+++ b/drivers/base/dma-mapping.c
@@ -176,13 +176,10 @@ int dmam_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 
 	rc = dma_declare_coherent_memory(dev, phys_addr, device_addr, size,
 					 flags);
-	if (rc) {
+	if (rc)
 		devres_add(dev, res);
-		rc = 0;
-	} else {
+	else
 		devres_free(res);
-		rc = -ENOMEM;
-	}
 
 	return rc;
 }
diff --git a/drivers/media/platform/soc_camera/sh_mobile_ceu_camera.c b/drivers/media/platform/soc_camera/sh_mobile_ceu_camera.c
index 96dc01750bc0..36762ec954e7 100644
--- a/drivers/media/platform/soc_camera/sh_mobile_ceu_camera.c
+++ b/drivers/media/platform/soc_camera/sh_mobile_ceu_camera.c
@@ -1708,11 +1708,10 @@ static int sh_mobile_ceu_probe(struct platform_device *pdev)
 		err = dma_declare_coherent_memory(&pdev->dev, res->start,
 						  res->start,
 						  resource_size(res),
-						  DMA_MEMORY_MAP |
 						  DMA_MEMORY_EXCLUSIVE);
-		if (!err) {
+		if (err) {
 			dev_err(&pdev->dev, "Unable to declare CEU memory.\n");
-			return -ENXIO;
+			return err;
 		}
 
 		pcdev->video_limit = resource_size(res);
diff --git a/drivers/scsi/NCR_Q720.c b/drivers/scsi/NCR_Q720.c
index 05835bf1bf9c..54e7d26908ee 100644
--- a/drivers/scsi/NCR_Q720.c
+++ b/drivers/scsi/NCR_Q720.c
@@ -217,8 +217,7 @@ NCR_Q720_probe(struct device *dev)
 	}
 	
 	if (dma_declare_coherent_memory(dev, base_addr, base_addr,
-					mem_size, DMA_MEMORY_MAP)
-	    != DMA_MEMORY_MAP) {
+					mem_size, 0)) {
 		printk(KERN_ERR "NCR_Q720: DMA declare memory failed\n");
 		goto out_release_region;
 	}
diff --git a/drivers/usb/host/ohci-sm501.c b/drivers/usb/host/ohci-sm501.c
index a8b8d8b8d9f3..21302a0f82e2 100644
--- a/drivers/usb/host/ohci-sm501.c
+++ b/drivers/usb/host/ohci-sm501.c
@@ -123,11 +123,11 @@ static int ohci_hcd_sm501_drv_probe(struct platform_device *pdev)
 	 * regular memory. The HCD_LOCAL_MEM flag does just that.
 	 */
 
-	if (!dma_declare_coherent_memory(dev, mem->start,
+	retval = dma_declare_coherent_memory(dev, mem->start,
 					 mem->start - mem->parent->start,
 					 resource_size(mem),
-					 DMA_MEMORY_MAP |
-					 DMA_MEMORY_EXCLUSIVE)) {
+					 DMA_MEMORY_EXCLUSIVE);
+	if (retval) {
 		dev_err(dev, "cannot declare coherent memory\n");
 		retval = -ENXIO;
 		goto err1;
diff --git a/drivers/usb/host/ohci-tmio.c b/drivers/usb/host/ohci-tmio.c
index cfcfadfc94fc..16d081a093bb 100644
--- a/drivers/usb/host/ohci-tmio.c
+++ b/drivers/usb/host/ohci-tmio.c
@@ -227,13 +227,10 @@ static int ohci_hcd_tmio_drv_probe(struct platform_device *dev)
 		goto err_ioremap_regs;
 	}
 
-	if (!dma_declare_coherent_memory(&dev->dev, sram->start,
-				sram->start,
-				resource_size(sram),
-				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE)) {
-		ret = -EBUSY;
+	ret = dma_declare_coherent_memory(&dev->dev, sram->start, sram->start,
+				resource_size(sram), DMA_MEMORY_EXCLUSIVE);
+	if (ret)
 		goto err_dma_declare;
-	}
 
 	if (cell->enable) {
 		ret = cell->enable(dev);
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index fb66fe98e61d..e33feccc35d1 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -683,9 +683,7 @@ static inline int dma_get_cache_alignment(void)
 #endif
 
 /* flags for the coherent memory api */
-#define	DMA_MEMORY_MAP			0x01
-#define DMA_MEMORY_IO			0x02
-#define DMA_MEMORY_EXCLUSIVE		0x04
+#define DMA_MEMORY_EXCLUSIVE		0x01
 
 #ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT
 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
@@ -698,7 +696,7 @@ static inline int
 dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 			    dma_addr_t device_addr, size_t size, int flags)
 {
-	return 0;
+	return -EINVAL;
 }
 
 static inline void
-- 
2.11.0

Re: [PATCH 1/2] dma-coherent: remove the DMA_MEMORY_INCLUDES_CHILDREN flag

[Robin Murphy]

On 27/06/17 21:17, Christoph Hellwig wrote:
> This flag was never implemented or used.

And at worst, we can always bring it back.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  Documentation/DMA-API.txt     | 4 ----
>  drivers/base/dma-coherent.c   | 2 --
>  drivers/char/virtio_console.c | 3 ---
>  include/linux/dma-mapping.h   | 3 +--
>  4 files changed, 1 insertion(+), 11 deletions(-)
> 
> diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
> index 6b20128fab8a..03072bc7ff74 100644
> --- a/Documentation/DMA-API.txt
> +++ b/Documentation/DMA-API.txt
> @@ -524,10 +524,6 @@ dma_alloc_coherent() be addressable using read()/write()/memcpy_toio() etc.
>  
>  One or both of these flags must be present.
>  
> -DMA_MEMORY_INCLUDES_CHILDREN - make the declared memory be allocated by
> -dma_alloc_coherent of any child devices of this one (for memory residing
> -on a bridge).
> -
>  DMA_MEMORY_EXCLUSIVE - only allocate memory from the declared regions. 
>  Do not allow dma_alloc_coherent() to fall back to system memory when
>  it's out of memory in the declared region.
> diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
> index 2ae24c28e70c..e70e33d5c902 100644
> --- a/drivers/base/dma-coherent.c
> +++ b/drivers/base/dma-coherent.c
> @@ -109,8 +109,6 @@ static int dma_assign_coherent_memory(struct device *dev,
>  		return -EBUSY;
>  
>  	dev->dma_mem = mem;
> -	/* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
> -
>  	return 0;
>  }
>  
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index ad843eb02ae7..48e86ce9fac8 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -451,9 +451,6 @@ static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size,
>  		 * device is created by remoteproc, the DMA memory is
>  		 * associated with the grandparent device:
>  		 * vdev => rproc => platform-dev.
> -		 * The code here would have been less quirky if
> -		 * DMA_MEMORY_INCLUDES_CHILDREN had been supported
> -		 * in dma-coherent.c
>  		 */
>  		if (!vq->vdev->dev.parent || !vq->vdev->dev.parent->parent)
>  			goto free_buf;
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 843ab866e0f4..fb66fe98e61d 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -685,8 +685,7 @@ static inline int dma_get_cache_alignment(void)
>  /* flags for the coherent memory api */
>  #define	DMA_MEMORY_MAP			0x01
>  #define DMA_MEMORY_IO			0x02
> -#define DMA_MEMORY_INCLUDES_CHILDREN	0x04
> -#define DMA_MEMORY_EXCLUSIVE		0x08
> +#define DMA_MEMORY_EXCLUSIVE		0x04
>  
>  #ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT
>  int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
> 

Re: [PATCH 2/2] dma-coherent: remove the DMA_MEMORY_MAP and DMA_MEMORY_IO flags

[Robin Murphy]

On 27/06/17 21:17, Christoph Hellwig wrote:
> DMA_MEMORY_IO was never used in the tree, so remove it.  That means there is
> no need for the DMA_MEMORY_MAP flag either now, so remove it as well and
> change dma_declare_coherent_memory to return a normal errno value.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

[...]

> diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
> index 10e7c022e8cf..b96bfffd314e 100644
> --- a/drivers/base/dma-mapping.c
> +++ b/drivers/base/dma-mapping.c
> @@ -176,13 +176,10 @@ int dmam_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
>  
>  	rc = dma_declare_coherent_memory(dev, phys_addr, device_addr, size,
>  					 flags);
> -	if (rc) {
> +	if (rc)

if (!rc)

>  		devres_add(dev, res);
> -		rc = 0;
> -	} else {
> +	else
>  		devres_free(res);
> -		rc = -ENOMEM;
> -	}
>  
>  	return rc;
>  }

[...]

> diff --git a/drivers/usb/host/ohci-sm501.c b/drivers/usb/host/ohci-sm501.c
> index a8b8d8b8d9f3..21302a0f82e2 100644
> --- a/drivers/usb/host/ohci-sm501.c
> +++ b/drivers/usb/host/ohci-sm501.c
> @@ -123,11 +123,11 @@ static int ohci_hcd_sm501_drv_probe(struct platform_device *pdev)
>  	 * regular memory. The HCD_LOCAL_MEM flag does just that.
>  	 */
>  
> -	if (!dma_declare_coherent_memory(dev, mem->start,
> +	retval = dma_declare_coherent_memory(dev, mem->start,
>  					 mem->start - mem->parent->start,
>  					 resource_size(mem),
> -					 DMA_MEMORY_MAP |
> -					 DMA_MEMORY_EXCLUSIVE)) {
> +					 DMA_MEMORY_EXCLUSIVE);
> +	if (retval) {
>  		dev_err(dev, "cannot declare coherent memory\n");
>  		retval = -ENXIO;

It looks like we could just let retval propagate here, rather than
rewriting it, since we're only bailing out of a probe routine.

Robin.

>  		goto err1;

Re: [PATCH 2/2] dma-coherent: remove the DMA_MEMORY_MAP and DMA_MEMORY_IO flags

[Christoph Hellwig]

Hi Marek,

thanks for the review. I'll fix those two issues up.

Re: [PATCH 2/2] dma-coherent: remove the DMA_MEMORY_MAP and DMA_MEMORY_IO flags

[Marek Szyprowski]

Hi Christoph,

On 2017-08-26 09:26, Christoph Hellwig wrote:
> DMA_MEMORY_IO was never used in the tree, so remove it.  That means there is
> no need for the DMA_MEMORY_MAP flag either now, so remove it as well and
> change dma_declare_coherent_memory to return a normal errno value.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

There are 2 minor issues, besides that:

Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---
>   Documentation/DMA-API.txt                          | 21 +---------
>   arch/arm/mach-imx/mach-imx27_visstrim_m10.c        | 43 +++++++-------------
>   arch/arm/mach-imx/mach-mx31moboard.c               | 12 +++---
>   arch/sh/drivers/pci/fixups-dreamcast.c             |  3 +-
>   drivers/base/dma-coherent.c                        | 46 +++++++---------------
>   drivers/base/dma-mapping.c                         |  7 +---
>   .../platform/soc_camera/sh_mobile_ceu_camera.c     |  5 +--
>   drivers/scsi/NCR_Q720.c                            |  3 +-
>   drivers/usb/host/ohci-sm501.c                      |  7 ++--
>   drivers/usb/host/ohci-tmio.c                       |  9 ++---
>   include/linux/dma-mapping.h                        |  6 +--
>   11 files changed, 50 insertions(+), 112 deletions(-)
>
> diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
> index ded50aed1cd8..da58585c7b3a 100644
> --- a/Documentation/DMA-API.txt
> +++ b/Documentation/DMA-API.txt
> @@ -590,30 +590,11 @@ size is the size of the area (must be multiples of PAGE_SIZE).
>   
>   flags can be ORed together and are:
>   
> -- DMA_MEMORY_MAP - request that the memory returned from
> -  dma_alloc_coherent() be directly writable.
> -
> -- DMA_MEMORY_IO - request that the memory returned from
> -  dma_alloc_coherent() be addressable using read()/write()/memcpy_toio() etc.
> -
> -One or both of these flags must be present.
> -
>   - DMA_MEMORY_EXCLUSIVE - only allocate memory from the declared regions.
>     Do not allow dma_alloc_coherent() to fall back to system memory when
>     it's out of memory in the declared region.
>   
> -The return value will be either DMA_MEMORY_MAP or DMA_MEMORY_IO and
> -must correspond to a passed in flag (i.e. no returning DMA_MEMORY_IO
> -if only DMA_MEMORY_MAP were passed in) for success or zero for
> -failure.
> -
> -Note, for DMA_MEMORY_IO returns, all subsequent memory returned by
> -dma_alloc_coherent() may no longer be accessed directly, but instead
> -must be accessed using the correct bus functions.  If your driver
> -isn't prepared to handle this contingency, it should not specify
> -DMA_MEMORY_IO in the input flags.
> -
> -As a simplification for the platforms, only **one** such region of
> +As a simplification for the platforms, only *one* such region of
>   memory may be declared per device.
>   
>   For reasons of efficiency, most platforms choose to track the declared
> diff --git a/arch/arm/mach-imx/mach-imx27_visstrim_m10.c b/arch/arm/mach-imx/mach-imx27_visstrim_m10.c
> index dd75a4756761..c2818af18c55 100644
> --- a/arch/arm/mach-imx/mach-imx27_visstrim_m10.c
> +++ b/arch/arm/mach-imx/mach-imx27_visstrim_m10.c
> @@ -245,7 +245,6 @@ static phys_addr_t mx2_camera_base __initdata;
>   static void __init visstrim_analog_camera_init(void)
>   {
>   	struct platform_device *pdev;
> -	int dma;
>   
>   	gpio_set_value(TVP5150_PWDN, 1);
>   	ndelay(1);
> @@ -258,12 +257,9 @@ static void __init visstrim_analog_camera_init(void)
>   	if (IS_ERR(pdev))
>   		return;
>   
> -	dma = dma_declare_coherent_memory(&pdev->dev,
> -				mx2_camera_base, mx2_camera_base,
> -				MX2_CAMERA_BUF_SIZE,
> -				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
> -	if (!(dma & DMA_MEMORY_MAP))
> -		return;
> +	dma_declare_coherent_memory(&pdev->dev, mx2_camera_base,
> +				    mx2_camera_base, MX2_CAMERA_BUF_SIZE,
> +				    DMA_MEMORY_EXCLUSIVE);
>   }
>   
>   static void __init visstrim_reserve(void)
> @@ -444,16 +440,13 @@ static const struct imx_ssi_platform_data visstrim_m10_ssi_pdata __initconst = {
>   static void __init visstrim_coda_init(void)
>   {
>   	struct platform_device *pdev;
> -	int dma;
>   
>   	pdev = imx27_add_coda();
> -	dma = dma_declare_coherent_memory(&pdev->dev,
> -					  mx2_camera_base + MX2_CAMERA_BUF_SIZE,
> -					  mx2_camera_base + MX2_CAMERA_BUF_SIZE,
> -					  MX2_CAMERA_BUF_SIZE,
> -					  DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
> -	if (!(dma & DMA_MEMORY_MAP))
> -		return;
> +	dma_declare_coherent_memory(&pdev->dev,
> +				    mx2_camera_base + MX2_CAMERA_BUF_SIZE,
> +				    mx2_camera_base + MX2_CAMERA_BUF_SIZE,
> +				    MX2_CAMERA_BUF_SIZE,
> +				    DMA_MEMORY_EXCLUSIVE);
>   }
>   
>   /* DMA deinterlace */
> @@ -466,24 +459,20 @@ static void __init visstrim_deinterlace_init(void)
>   {
>   	int ret = -ENOMEM;
>   	struct platform_device *pdev = &visstrim_deinterlace;
> -	int dma;
>   
>   	ret = platform_device_register(pdev);
>   
> -	dma = dma_declare_coherent_memory(&pdev->dev,
> -					  mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
> -					  mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
> -					  MX2_CAMERA_BUF_SIZE,
> -					  DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
> -	if (!(dma & DMA_MEMORY_MAP))
> -		return;
> +	dma_declare_coherent_memory(&pdev->dev,
> +				    mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
> +				    mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
> +				    MX2_CAMERA_BUF_SIZE,
> +				    DMA_MEMORY_EXCLUSIVE);
>   }
>   
>   /* Emma-PrP for format conversion */
>   static void __init visstrim_emmaprp_init(void)
>   {
>   	struct platform_device *pdev;
> -	int dma;
>   
>   	pdev = imx27_add_mx2_emmaprp();
>   	if (IS_ERR(pdev))
> @@ -493,12 +482,10 @@ static void __init visstrim_emmaprp_init(void)
>   	 * Use the same memory area as the analog camera since both
>   	 * devices are, by nature, exclusive.
>   	 */
> -	dma = dma_declare_coherent_memory(&pdev->dev,
> +	dma_declare_coherent_memory(&pdev->dev,
>   				mx2_camera_base, mx2_camera_base,
>   				MX2_CAMERA_BUF_SIZE,
> -				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
> -	if (!(dma & DMA_MEMORY_MAP))
> -		pr_err("Failed to declare memory for emmaprp\n");
> +				DMA_MEMORY_EXCLUSIVE);

Can we keep error message? It might be useful in case of any problems, 
because
the return value is not propagated otherwise.

> > [...]

> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 9b12cb255063..92f7d84e51f5 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -708,9 +708,7 @@ static inline int dma_get_cache_alignment(void)
>   #endif
>   
>   /* flags for the coherent memory api */
> -#define	DMA_MEMORY_MAP			0x01
> -#define DMA_MEMORY_IO			0x02
> -#define DMA_MEMORY_EXCLUSIVE		0x04
> +#define DMA_MEMORY_EXCLUSIVE		0x01
>   
>   #ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT
>   int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
> @@ -723,7 +721,7 @@ static inline int
>   dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
>   			    dma_addr_t device_addr, size_t size, int flags)
>   {
> -	return 0;
> +	return -EINVAL;

ENOSYS ?

>   }
>   
>   static inline void

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

Re: [PATCH 2/2] dma-coherent: remove the DMA_MEMORY_MAP and DMA_MEMORY_IO flags

[Christoph Hellwig]

Can I get a review for this one?

[PATCH 2/2] dma-coherent: remove the DMA_MEMORY_MAP and DMA_MEMORY_IO flags

[Christoph Hellwig]

DMA_MEMORY_IO was never used in the tree, so remove it.  That means there is
no need for the DMA_MEMORY_MAP flag either now, so remove it as well and
change dma_declare_coherent_memory to return a normal errno value.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 Documentation/DMA-API.txt                          | 21 +---------
 arch/arm/mach-imx/mach-imx27_visstrim_m10.c        | 43 +++++++-------------
 arch/arm/mach-imx/mach-mx31moboard.c               | 12 +++---
 arch/sh/drivers/pci/fixups-dreamcast.c             |  3 +-
 drivers/base/dma-coherent.c                        | 46 +++++++---------------
 drivers/base/dma-mapping.c                         |  7 +---
 .../platform/soc_camera/sh_mobile_ceu_camera.c     |  5 +--
 drivers/scsi/NCR_Q720.c                            |  3 +-
 drivers/usb/host/ohci-sm501.c                      |  7 ++--
 drivers/usb/host/ohci-tmio.c                       |  9 ++---
 include/linux/dma-mapping.h                        |  6 +--
 11 files changed, 50 insertions(+), 112 deletions(-)

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index ded50aed1cd8..da58585c7b3a 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -590,30 +590,11 @@ size is the size of the area (must be multiples of PAGE_SIZE).
 
 flags can be ORed together and are:
 
-- DMA_MEMORY_MAP - request that the memory returned from
-  dma_alloc_coherent() be directly writable.
-
-- DMA_MEMORY_IO - request that the memory returned from
-  dma_alloc_coherent() be addressable using read()/write()/memcpy_toio() etc.
-
-One or both of these flags must be present.
-
 - DMA_MEMORY_EXCLUSIVE - only allocate memory from the declared regions.
   Do not allow dma_alloc_coherent() to fall back to system memory when
   it's out of memory in the declared region.
 
-The return value will be either DMA_MEMORY_MAP or DMA_MEMORY_IO and
-must correspond to a passed in flag (i.e. no returning DMA_MEMORY_IO
-if only DMA_MEMORY_MAP were passed in) for success or zero for
-failure.
-
-Note, for DMA_MEMORY_IO returns, all subsequent memory returned by
-dma_alloc_coherent() may no longer be accessed directly, but instead
-must be accessed using the correct bus functions.  If your driver
-isn't prepared to handle this contingency, it should not specify
-DMA_MEMORY_IO in the input flags.
-
-As a simplification for the platforms, only **one** such region of
+As a simplification for the platforms, only *one* such region of
 memory may be declared per device.
 
 For reasons of efficiency, most platforms choose to track the declared
diff --git a/arch/arm/mach-imx/mach-imx27_visstrim_m10.c b/arch/arm/mach-imx/mach-imx27_visstrim_m10.c
index dd75a4756761..c2818af18c55 100644
--- a/arch/arm/mach-imx/mach-imx27_visstrim_m10.c
+++ b/arch/arm/mach-imx/mach-imx27_visstrim_m10.c
@@ -245,7 +245,6 @@ static phys_addr_t mx2_camera_base __initdata;
 static void __init visstrim_analog_camera_init(void)
 {
 	struct platform_device *pdev;
-	int dma;
 
 	gpio_set_value(TVP5150_PWDN, 1);
 	ndelay(1);
@@ -258,12 +257,9 @@ static void __init visstrim_analog_camera_init(void)
 	if (IS_ERR(pdev))
 		return;
 
-	dma = dma_declare_coherent_memory(&pdev->dev,
-				mx2_camera_base, mx2_camera_base,
-				MX2_CAMERA_BUF_SIZE,
-				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
-		return;
+	dma_declare_coherent_memory(&pdev->dev, mx2_camera_base,
+				    mx2_camera_base, MX2_CAMERA_BUF_SIZE,
+				    DMA_MEMORY_EXCLUSIVE);
 }
 
 static void __init visstrim_reserve(void)
@@ -444,16 +440,13 @@ static const struct imx_ssi_platform_data visstrim_m10_ssi_pdata __initconst = {
 static void __init visstrim_coda_init(void)
 {
 	struct platform_device *pdev;
-	int dma;
 
 	pdev = imx27_add_coda();
-	dma = dma_declare_coherent_memory(&pdev->dev,
-					  mx2_camera_base + MX2_CAMERA_BUF_SIZE,
-					  mx2_camera_base + MX2_CAMERA_BUF_SIZE,
-					  MX2_CAMERA_BUF_SIZE,
-					  DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
-		return;
+	dma_declare_coherent_memory(&pdev->dev,
+				    mx2_camera_base + MX2_CAMERA_BUF_SIZE,
+				    mx2_camera_base + MX2_CAMERA_BUF_SIZE,
+				    MX2_CAMERA_BUF_SIZE,
+				    DMA_MEMORY_EXCLUSIVE);
 }
 
 /* DMA deinterlace */
@@ -466,24 +459,20 @@ static void __init visstrim_deinterlace_init(void)
 {
 	int ret = -ENOMEM;
 	struct platform_device *pdev = &visstrim_deinterlace;
-	int dma;
 
 	ret = platform_device_register(pdev);
 
-	dma = dma_declare_coherent_memory(&pdev->dev,
-					  mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
-					  mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
-					  MX2_CAMERA_BUF_SIZE,
-					  DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
-		return;
+	dma_declare_coherent_memory(&pdev->dev,
+				    mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
+				    mx2_camera_base + 2 * MX2_CAMERA_BUF_SIZE,
+				    MX2_CAMERA_BUF_SIZE,
+				    DMA_MEMORY_EXCLUSIVE);
 }
 
 /* Emma-PrP for format conversion */
 static void __init visstrim_emmaprp_init(void)
 {
 	struct platform_device *pdev;
-	int dma;
 
 	pdev = imx27_add_mx2_emmaprp();
 	if (IS_ERR(pdev))
@@ -493,12 +482,10 @@ static void __init visstrim_emmaprp_init(void)
 	 * Use the same memory area as the analog camera since both
 	 * devices are, by nature, exclusive.
 	 */
-	dma = dma_declare_coherent_memory(&pdev->dev,
+	dma_declare_coherent_memory(&pdev->dev,
 				mx2_camera_base, mx2_camera_base,
 				MX2_CAMERA_BUF_SIZE,
-				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
-		pr_err("Failed to declare memory for emmaprp\n");
+				DMA_MEMORY_EXCLUSIVE);
 }
 
 /* Audio */
diff --git a/arch/arm/mach-imx/mach-mx31moboard.c b/arch/arm/mach-imx/mach-mx31moboard.c
index bde9a9af6714..3cd030960c98 100644
--- a/arch/arm/mach-imx/mach-mx31moboard.c
+++ b/arch/arm/mach-imx/mach-mx31moboard.c
@@ -475,7 +475,7 @@ static phys_addr_t mx3_camera_base __initdata;
 
 static int __init mx31moboard_init_cam(void)
 {
-	int dma, ret = -ENOMEM;
+	int dma, ret;
 	struct platform_device *pdev;
 
 	imx31_add_ipu_core();
@@ -484,11 +484,11 @@ static int __init mx31moboard_init_cam(void)
 	if (IS_ERR(pdev))
 		return PTR_ERR(pdev);
 
-	dma = dma_declare_coherent_memory(&pdev->dev,
-					mx3_camera_base, mx3_camera_base,
-					MX3_CAMERA_BUF_SIZE,
-					DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
-	if (!(dma & DMA_MEMORY_MAP))
+	ret = dma_declare_coherent_memory(&pdev->dev,
+					  mx3_camera_base, mx3_camera_base,
+					  MX3_CAMERA_BUF_SIZE,
+					  DMA_MEMORY_EXCLUSIVE);
+	if (ret)
 		goto err;
 
 	ret = platform_device_add(pdev);
diff --git a/arch/sh/drivers/pci/fixups-dreamcast.c b/arch/sh/drivers/pci/fixups-dreamcast.c
index 1d1c5a227e50..c931d5872ffe 100644
--- a/arch/sh/drivers/pci/fixups-dreamcast.c
+++ b/arch/sh/drivers/pci/fixups-dreamcast.c
@@ -63,11 +63,10 @@ static void gapspci_fixup_resources(struct pci_dev *dev)
 		res.end = GAPSPCI_DMA_BASE + GAPSPCI_DMA_SIZE - 1;
 		res.flags = IORESOURCE_MEM;
 		pcibios_resource_to_bus(dev->bus, &region, &res);
-		BUG_ON(!dma_declare_coherent_memory(&dev->dev,
+		BUG_ON(dma_declare_coherent_memory(&dev->dev,
 						res.start,
 						region.start,
 						resource_size(&res),
-						DMA_MEMORY_MAP |
 						DMA_MEMORY_EXCLUSIVE));
 		break;
 	default:
diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index 6f6dc4d41788..b275eeb739f1 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -46,15 +46,10 @@ static bool dma_init_coherent_memory(
 	int pages = size >> PAGE_SHIFT;
 	int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
 
-	if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
-		goto out;
 	if (!size)
 		goto out;
 
-	if (flags & DMA_MEMORY_MAP)
-		mem_base = memremap(phys_addr, size, MEMREMAP_WC);
-	else
-		mem_base = ioremap(phys_addr, size);
+	mem_base = memremap(phys_addr, size, MEMREMAP_WC);
 	if (!mem_base)
 		goto out;
 
@@ -77,12 +72,8 @@ static bool dma_init_coherent_memory(
 
 out:
 	kfree(dma_mem);
-	if (mem_base) {
-		if (flags & DMA_MEMORY_MAP)
-			memunmap(mem_base);
-		else
-			iounmap(mem_base);
-	}
+	if (mem_base)
+		memunmap(mem_base);
 	return false;
 }
 
@@ -91,10 +82,7 @@ static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
 	if (!mem)
 		return;
 
-	if (mem->flags & DMA_MEMORY_MAP)
-		memunmap(mem->virt_base);
-	else
-		iounmap(mem->virt_base);
+	memunmap(mem->virt_base);
 	kfree(mem->bitmap);
 	kfree(mem);
 }
@@ -116,16 +104,16 @@ int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 				dma_addr_t device_addr, size_t size, int flags)
 {
 	struct dma_coherent_mem *mem;
+	int ret;
 
-	if (!dma_init_coherent_memory(phys_addr, device_addr, size, flags,
-				      &mem))
-		return 0;
-
-	if (dma_assign_coherent_memory(dev, mem) == 0)
-		return flags & DMA_MEMORY_MAP ? DMA_MEMORY_MAP : DMA_MEMORY_IO;
+	ret = dma_init_coherent_memory(phys_addr, device_addr, size, flags, &mem);
+	if (ret)
+		return ret;
 
-	dma_release_coherent_memory(mem);
-	return 0;
+	ret = dma_assign_coherent_memory(dev, mem);
+	if (ret)
+		dma_release_coherent_memory(mem);
+	return ret;
 }
 EXPORT_SYMBOL(dma_declare_coherent_memory);
 
@@ -186,15 +174,9 @@ static void *__dma_alloc_from_coherent(struct dma_coherent_mem *mem,
 	 */
 	*dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
 	ret = mem->virt_base + (pageno << PAGE_SHIFT);
-	dma_memory_map = (mem->flags & DMA_MEMORY_MAP);
 	spin_unlock_irqrestore(&mem->spinlock, flags);
-	if (dma_memory_map)
-		memset(ret, 0, size);
-	else
-		memset_io(ret, 0, size);
-
+	memset(ret, 0, size);
 	return ret;
-
 err:
 	spin_unlock_irqrestore(&mem->spinlock, flags);
 	return NULL;
@@ -360,7 +342,7 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
 
 	if (!mem &&
 	    !dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
-				      DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
+				      DMA_MEMORY_EXCLUSIVE,
 				      &mem)) {
 		pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
 			&rmem->base, (unsigned long)rmem->size / SZ_1M);
diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
index b555ff9dd8fc..e584eddef0a7 100644
--- a/drivers/base/dma-mapping.c
+++ b/drivers/base/dma-mapping.c
@@ -176,13 +176,10 @@ int dmam_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 
 	rc = dma_declare_coherent_memory(dev, phys_addr, device_addr, size,
 					 flags);
-	if (rc) {
+	if (!rc)
 		devres_add(dev, res);
-		rc = 0;
-	} else {
+	else
 		devres_free(res);
-		rc = -ENOMEM;
-	}
 
 	return rc;
 }
diff --git a/drivers/media/platform/soc_camera/sh_mobile_ceu_camera.c b/drivers/media/platform/soc_camera/sh_mobile_ceu_camera.c
index 96dc01750bc0..36762ec954e7 100644
--- a/drivers/media/platform/soc_camera/sh_mobile_ceu_camera.c
+++ b/drivers/media/platform/soc_camera/sh_mobile_ceu_camera.c
@@ -1708,11 +1708,10 @@ static int sh_mobile_ceu_probe(struct platform_device *pdev)
 		err = dma_declare_coherent_memory(&pdev->dev, res->start,
 						  res->start,
 						  resource_size(res),
-						  DMA_MEMORY_MAP |
 						  DMA_MEMORY_EXCLUSIVE);
-		if (!err) {
+		if (err) {
 			dev_err(&pdev->dev, "Unable to declare CEU memory.\n");
-			return -ENXIO;
+			return err;
 		}
 
 		pcdev->video_limit = resource_size(res);
diff --git a/drivers/scsi/NCR_Q720.c b/drivers/scsi/NCR_Q720.c
index 05835bf1bf9c..54e7d26908ee 100644
--- a/drivers/scsi/NCR_Q720.c
+++ b/drivers/scsi/NCR_Q720.c
@@ -217,8 +217,7 @@ NCR_Q720_probe(struct device *dev)
 	}
 	
 	if (dma_declare_coherent_memory(dev, base_addr, base_addr,
-					mem_size, DMA_MEMORY_MAP)
-	    != DMA_MEMORY_MAP) {
+					mem_size, 0)) {
 		printk(KERN_ERR "NCR_Q720: DMA declare memory failed\n");
 		goto out_release_region;
 	}
diff --git a/drivers/usb/host/ohci-sm501.c b/drivers/usb/host/ohci-sm501.c
index a8b8d8b8d9f3..d4e0f7cd96fa 100644
--- a/drivers/usb/host/ohci-sm501.c
+++ b/drivers/usb/host/ohci-sm501.c
@@ -123,13 +123,12 @@ static int ohci_hcd_sm501_drv_probe(struct platform_device *pdev)
 	 * regular memory. The HCD_LOCAL_MEM flag does just that.
 	 */
 
-	if (!dma_declare_coherent_memory(dev, mem->start,
+	retval = dma_declare_coherent_memory(dev, mem->start,
 					 mem->start - mem->parent->start,
 					 resource_size(mem),
-					 DMA_MEMORY_MAP |
-					 DMA_MEMORY_EXCLUSIVE)) {
+					 DMA_MEMORY_EXCLUSIVE);
+	if (retval) {
 		dev_err(dev, "cannot declare coherent memory\n");
-		retval = -ENXIO;
 		goto err1;
 	}
 
diff --git a/drivers/usb/host/ohci-tmio.c b/drivers/usb/host/ohci-tmio.c
index cfcfadfc94fc..16d081a093bb 100644
--- a/drivers/usb/host/ohci-tmio.c
+++ b/drivers/usb/host/ohci-tmio.c
@@ -227,13 +227,10 @@ static int ohci_hcd_tmio_drv_probe(struct platform_device *dev)
 		goto err_ioremap_regs;
 	}
 
-	if (!dma_declare_coherent_memory(&dev->dev, sram->start,
-				sram->start,
-				resource_size(sram),
-				DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE)) {
-		ret = -EBUSY;
+	ret = dma_declare_coherent_memory(&dev->dev, sram->start, sram->start,
+				resource_size(sram), DMA_MEMORY_EXCLUSIVE);
+	if (ret)
 		goto err_dma_declare;
-	}
 
 	if (cell->enable) {
 		ret = cell->enable(dev);
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 9b12cb255063..92f7d84e51f5 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -708,9 +708,7 @@ static inline int dma_get_cache_alignment(void)
 #endif
 
 /* flags for the coherent memory api */
-#define	DMA_MEMORY_MAP			0x01
-#define DMA_MEMORY_IO			0x02
-#define DMA_MEMORY_EXCLUSIVE		0x04
+#define DMA_MEMORY_EXCLUSIVE		0x01
 
 #ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT
 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
@@ -723,7 +721,7 @@ static inline int
 dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 			    dma_addr_t device_addr, size_t size, int flags)
 {
-	return 0;
+	return -EINVAL;
 }
 
 static inline void
-- 
2.11.0