Sricharan, Robin,
I gave this series a go on ACPI and apart from an SMMU v3 fix-up
it seems to work, more thorough testing required though.
A key question below.
On Wed, Nov 30, 2016 at 05:52:16AM +0530, Sricharan R wrote:
> From: Robin Murphy <robin.mur...@arm.com>
>
> IOMMU configuration represents unchanging properties of the hardware,
> and as such should only need happen once in a device's lifetime, but
> the necessary interaction with the IOMMU device and driver complicates
> exactly when that point should be.
>
> Since the only reasonable tool available for handling the inter-device
> dependency is probe deferral, we need to prepare of_iommu_configure()
> to run later than it is currently called (i.e. at driver probe rather
> than device creation), to handle being retried, and to tell whether a
> not-yet present IOMMU should be waited for or skipped (by virtue of
> having declared a built-in driver or not).
>
> Signed-off-by: Robin Murphy <robin.mur...@arm.com>
> ---
> drivers/iommu/of_iommu.c | 30 +++++++++++++++++++++++++++++-
> 1 file changed, 29 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index ee49081..349bd1d 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -104,12 +104,20 @@ int of_get_dma_window(struct device_node *dn, const
> char *prefix, int index,
> int err;
>
> ops = iommu_get_instance(fwnode);
> - if (!ops || !ops->of_xlate)
> + if ((ops && !ops->of_xlate) ||
> + (!ops && !of_match_node(&__iommu_of_table, iommu_spec->np)))
IIUC of_match_node() here is there to check there is a driver compiled
in for this device_node (aka compatible string in OF world), correct ?
If that's the case (and I think that's what Sricharan was referring to
in his ACPI query) I need to cook-up something on the ACPI side to
emulate the OF linker table behaviour (or anyway to detect a driver is
actually in the kernel), it is not that difficult but it is key to know,
I will give it some thought to make it as clean as possible.
Thanks,
Lorenzo
> return NULL;
>
> err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
> if (err)
> return ERR_PTR(err);
> + /*
> + * The otherwise-empty fwspec handily serves to indicate the specific
> + * IOMMU device we're waiting for, which will be useful if we ever get
> + * a proper probe-ordering dependency mechanism in future.
> + */
> + if (!ops)
> + return ERR_PTR(-EPROBE_DEFER);
>
> err = ops->of_xlate(dev, iommu_spec);
> if (err)
> @@ -186,14 +194,34 @@ const struct iommu_ops *of_iommu_configure(struct
> device *dev,
> struct device_node *master_np)
> {
> const struct iommu_ops *ops;
> + struct iommu_fwspec *fwspec = dev->iommu_fwspec;
>
> if (!master_np)
> return NULL;
>
> + if (fwspec) {
> + if (fwspec->ops)
> + return fwspec->ops;
> +
> + /* In the deferred case, start again from scratch */
> + iommu_fwspec_free(dev);
> + }
> +
> if (dev_is_pci(dev))
> ops = of_pci_iommu_init(to_pci_dev(dev), master_np);
> else
> ops = of_platform_iommu_init(dev, master_np);
> + /*
> + * If we have reason to believe the IOMMU driver missed the initial
> + * add_device callback for dev, replay it to get things in order.
> + */
> + if (!IS_ERR_OR_NULL(ops) && ops->add_device &&
> + dev->bus && !dev->iommu_group) {
> + int err = ops->add_device(dev);
> +
> + if (err)
> + ops = ERR_PTR(err);
> + }
>
> return IS_ERR(ops) ? NULL : ops;
> }
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of
> Code Aurora Forum, hosted by The Linux Foundation
>
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