On Fri, Dec 28, 2012 at 09:53:47AM +0530, Prathyush K wrote:

On Thu, Dec 27, 2012 at 7:45 PM, Marek Szyprowski
[off-list ref]wrote:

quoted

Hello,


On 12/27/2012 8:14 AM, Prathyush K wrote:

quoted

This patch adds EXPORT_SYMBOL calls to the three arm iommu
functions - arm_iommu_create_mapping, arm_iommu_free_mapping
and arm_iommu_attach_device. These functions can now be called
from dynamic modules.

Could You describe a bit more why those functions might be needed by
dynamic modules?

Hi Marek,

We are adding iommu support to exynos gsc and s5p-mfc.
And these two drivers need to be built as modules to improve boot time.

We're calling these three functions from inside these drivers:
e.g.
mapping = arm_iommu_create_mapping(&platform_bus_type, 0x20000000, SZ_256M,
4);
arm_iommu_attach_device(mdev, mapping);

The driver shouldn't have to call these low-level functions directly,
something's wrong if you need that.

How is the DMA address management different here from other system/io mmus? is
that 256M window a hardware restriction?

-Olof