[PATCH v4 2/6] ACPI: Move IOMMU setup code out of IORT
Robin Murphy
robin.murphy at arm.com
Fri Jun 18 02:16:19 PDT 2021
On 2021-06-18 08:41, Jean-Philippe Brucker wrote:
> Hi Eric,
>
> On Wed, Jun 16, 2021 at 11:35:13AM +0200, Eric Auger wrote:
>>> -const struct iommu_ops *iort_iommu_configure_id(struct device *dev,
>>> - const u32 *id_in)
>>> +int iort_iommu_configure_id(struct device *dev, const u32 *id_in)
>>> {
>>> struct acpi_iort_node *node;
>>> - const struct iommu_ops *ops;
>>> + const struct iommu_ops *ops = NULL;
>
> Oops, I need to remove this (and add -Werror to my tests.)
>
>
>>> +static const struct iommu_ops *acpi_iommu_configure_id(struct device *dev,
>>> + const u32 *id_in)
>>> +{
>>> + int err;
>>> + const struct iommu_ops *ops;
>>> +
>>> + /*
>>> + * If we already translated the fwspec there is nothing left to do,
>>> + * return the iommu_ops.
>>> + */
>>> + ops = acpi_iommu_fwspec_ops(dev);
>>> + if (ops)
>>> + return ops;
>>> +
>>> + err = iort_iommu_configure_id(dev, id_in);
>>> +
>>> + /*
>>> + * 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 (!err && dev->bus && !device_iommu_mapped(dev))
>>> + err = iommu_probe_device(dev);
>> Previously we had:
>> if (!err) {
>> ops = iort_fwspec_iommu_ops(dev);
>> err = iort_add_device_replay(dev);
>> }
>>
>> Please can you explain the transform? I see the
>>
>> acpi_iommu_fwspec_ops call below but is it not straightforward to me.
>
> I figured that iort_add_device_replay() is only used once and is
> sufficiently simple to be inlined manually (saving 10 lines). Then I
> replaced the ops assignment with returns, which saves another line and may
> be slightly clearer? I guess it's mostly a matter of taste, the behavior
> should be exactly the same.
Right, IIRC the multiple assignments to ops were more of a haphazard
evolution inherited from the DT version, and looking at it now I think
the multiple-return is indeed a bit nicer.
Similarly, it looks like the factoring out of iort_add_device_replay()
was originally an attempt to encapsulate the IOMMU_API dependency, but
things have moved around a lot since then, so that seems like a sensible
simplification to make too.
Robin.
>
>> Also the comment mentions replay. Unsure if it is still OK.
>
> The "replay" part is, but "add_device" isn't accurate because it has since
> been replaced by probe_device. I'll refresh the comment.
>
> Thanks,
> Jean
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