[PATCH 0/3] Use dma_mmap_coherent to support IOMMU mapper

There is a dma_mmap_coherent() API in some architectures.  This API
provides a mmap function for memory allocated by dma_alloc_coherent().
Some drivers mmap a dma_addr_t returned by dma_alloc_coherent() as a
physical address.  But such drivers do not work correctly when IOMMU
mapper is used.

Hideki EIRAKU (3):
  ARM: dma-mapping: define ARCH_HAS_DMA_MMAP_COHERENT
  media: videobuf2-dma-contig: use dma_mmap_coherent if available
  fbdev: sh_mobile_lcdc: use dma_mmap_coherent if available

 arch/arm/include/asm/dma-mapping.h         |    1 +
 drivers/media/video/videobuf2-dma-contig.c |   18 ++++++++++++++++++
 drivers/video/sh_mobile_lcdcfb.c           |   14 ++++++++++++++
 3 files changed, 33 insertions(+), 0 deletions(-)

ARCH_HAS_DMA_MMAP_COHERENT indicates that there is dma_mmap_coherent() API
in this architecture.  The name is already defined in PowerPC.

Signed-off-by: Hideki EIRAKU <redacted>
---
 arch/arm/include/asm/dma-mapping.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index bbef15d..f41cd30 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h

@@ -187,6 +187,7 @@ extern int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 			struct dma_attrs *attrs);
 
 #define dma_mmap_coherent(d, v, c, h, s) dma_mmap_attrs(d, v, c, h, s, NULL)
+#define ARCH_HAS_DMA_MMAP_COHERENT
 
 static inline int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
 				  void *cpu_addr, dma_addr_t dma_addr,

-- 
1.7.0.4

fb_mmap() implemented in fbmem.c uses smem_start as the physical
address of the frame buffer.  In the sh_mobile_lcdc driver, the
smem_start is a dma_addr_t that is not a physical address when IOMMU is
enabled.  dma_mmap_coherent() maps the address correctly.  It is
available on ARM platforms.

Signed-off-by: Hideki EIRAKU <redacted>
---
 drivers/video/sh_mobile_lcdcfb.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/video/sh_mobile_lcdcfb.c b/drivers/video/sh_mobile_lcdcfb.c
index e672698..65732c4 100644
--- a/drivers/video/sh_mobile_lcdcfb.c
+++ b/drivers/video/sh_mobile_lcdcfb.c

@@ -1393,6 +1393,17 @@ static int sh_mobile_lcdc_blank(int blank, struct fb_info *info)
 	return 0;
 }
 
+#ifdef ARCH_HAS_DMA_MMAP_COHERENT
+static int
+sh_mobile_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	struct sh_mobile_lcdc_chan *ch = info->par;
+
+	return dma_mmap_coherent(ch->lcdc->dev, vma, ch->fb_mem,
+				 ch->dma_handle, ch->fb_size);
+}
+#endif
+
 static struct fb_ops sh_mobile_lcdc_ops = {
 	.owner          = THIS_MODULE,
 	.fb_setcolreg	= sh_mobile_lcdc_setcolreg,

@@ -1408,6 +1419,9 @@ static struct fb_ops sh_mobile_lcdc_ops = {
 	.fb_release	= sh_mobile_release,
 	.fb_check_var	= sh_mobile_check_var,
 	.fb_set_par	= sh_mobile_set_par,
+#ifdef ARCH_HAS_DMA_MMAP_COHERENT
+	.fb_mmap	= sh_mobile_fb_mmap,
+#endif
 };
 
 static void

-- 
1.7.0.4

Previously the vb2_dma_contig_mmap() function was using a dma_addr_t as a
physical address.  The two addressses are not necessarily the same.
For example, when using the IOMMU funtion on certain platforms, dma_addr_t
addresses are not directly mappable physical address.
dma_mmap_coherent() maps the address correctly.
It is available on ARM platforms.

Signed-off-by: Hideki EIRAKU <redacted>
---
 drivers/media/video/videobuf2-dma-contig.c |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/drivers/media/video/videobuf2-dma-contig.c b/drivers/media/video/videobuf2-dma-contig.c
index 4b71326..4dc85ab 100644
--- a/drivers/media/video/videobuf2-dma-contig.c
+++ b/drivers/media/video/videobuf2-dma-contig.c

@@ -101,14 +101,32 @@ static unsigned int vb2_dma_contig_num_users(void *buf_priv)
 static int vb2_dma_contig_mmap(void *buf_priv, struct vm_area_struct *vma)
 {
 	struct vb2_dc_buf *buf = buf_priv;
+#ifdef ARCH_HAS_DMA_MMAP_COHERENT
+	int ret;
+#endif
 
 	if (!buf) {
 		printk(KERN_ERR "No buffer to map\n");
 		return -EINVAL;
 	}
 
+#ifdef ARCH_HAS_DMA_MMAP_COHERENT
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	ret = dma_mmap_coherent(buf->conf->dev, vma, buf->vaddr, buf->dma_addr,
+				buf->size);
+	if (ret) {
+		pr_err("Remapping memory failed, error: %d\n", ret);
+		return ret;
+	}
+	vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
+	vma->vm_private_data = &buf->handler;
+	vma->vm_ops = &vb2_common_vm_ops;
+	vma->vm_ops->open(vma);
+	return 0;
+#else
 	return vb2_mmap_pfn_range(vma, buf->dma_addr, buf->size,
 				  &vb2_common_vm_ops, &buf->handler);
+#endif
 }
 
 static void *vb2_dma_contig_get_userptr(void *alloc_ctx, unsigned long vaddr,

-- 
1.7.0.4

Hi Eiraku-san,

Thank you for the patch.

On Wednesday 25 July 2012 15:29:24 Hideki EIRAKU wrote:

fb_mmap() implemented in fbmem.c uses smem_start as the physical
address of the frame buffer.  In the sh_mobile_lcdc driver, the
smem_start is a dma_addr_t that is not a physical address when IOMMU is
enabled.  dma_mmap_coherent() maps the address correctly.  It is
available on ARM platforms.

This looks good to me, but will need to be rebased on top of the 
sh_mobile_lcdc patches currently queued for v3.6. You can find them in the 
fbdev-next branch of git://github.com/schandinat/linux-2.6.git.

In particular, these patches add support for overlays exported through 
additional fbdev devices. You will need to initialize .fb_mmap in both 
sh_mobile_lcdc_overlay_ops and sh_mobile_lcdc_ops.

-- 
Regards,

Laurent Pinchart

The ARM architecture now defines ARCH_HAS_DMA_MMAP_COHERENT, there's no
need to define it privately anymore.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 sound/core/pcm_native.c |    7 -------
 1 files changed, 0 insertions(+), 7 deletions(-)

Hi Eiraku-san,

Could you please add this cleanup patch to your "Use dma_mmap_coherent to
support IOMMU mapper" series ?

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 53b5ada..84ead60 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c

@@ -3156,13 +3156,6 @@ static const struct vm_operations_struct snd_pcm_vm_ops_data_fault = {
 	.fault =	snd_pcm_mmap_data_fault,
 };
 
-#ifndef ARCH_HAS_DMA_MMAP_COHERENT
-/* This should be defined / handled globally! */
-#ifdef CONFIG_ARM
-#define ARCH_HAS_DMA_MMAP_COHERENT
-#endif
-#endif
-
 /*
  * mmap the DMA buffer on RAM
  */

-- 
Regards,

Laurent Pinchart