On Fri, Nov 01, 2013 at 08:49:09AM +0200, Hiroshi Doyu wrote:
> On Thu, 31 Oct 2013 18:53:22 +0100
> Stephen Warren <swarren@xxxxxxxxxxxxx> wrote:
> ...
> > We're talking about memory-mapped on-SoC devices here, that generally
> > only exist inside Tegra SoCs.
> >
> > Even ignoring that (i.e. expanding the argument to arbitrary modules),
> > having drivers that perform bus-master transactions call a function
> > of_iommu_attach() or similar, which does nothing if the device isn't
> > behind an IOMMU but otherwise does whatever is required, seems like it
> > isn't much of an imposition.
>
> Where do you expect of_iommu_attach() to be called?
> I thought something below:
>
> Modified drivers/base/dd.c
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 35fa368..92ec2e9 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -278,6 +278,10 @@ static int really_probe(struct device *dev, struct device_driver *drv)
> if (ret)
> goto probe_failed;
>
> + ret = of_iommu_attach(dev);
> + if (ret)
> + goto probe_failed;
> +
> if (driver_sysfs_add(dev)) {
> printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
> __func__, dev_name(dev));
>
The patches for late interrupt reference resolution introduced a
separate function, of_platform_probe(), with the intent of having it
call potentially many resource allocation hooks. The function needs to
be platform_device specific, and therefore is called from within the
platform_drv_probe() function. The reason is that interrupts are stored
as resources within struct platform_device, so you need to have access
to a platform device.
I think that devices that require attachment to an IOMMU will always end
up being platform devices too, so even if it isn't a strict requirement
here it would still make sense to use a similar infrastructure to avoid
cluttering the core code with too many loose function calls.
Thierry
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