Re: [PATCH v3 2/6] iommu/virtio: Add topology helpers

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

On Fri, Sep 04, 2020 at 06:22:12PM +0200, Auger Eric wrote:
> > +/**
> > + * virt_dma_configure - Configure DMA of virtualized devices
> > + * @dev: the endpoint
> > + *
> > + * Setup the DMA and IOMMU ops of a virtual device, for platforms without DT or
> > + * ACPI.
> > + *
> > + * Return: -EPROBE_DEFER if the device is managed by an IOMMU that hasn't been
> > + *   probed yet, 0 otherwise
> > + */
> > +int virt_dma_configure(struct device *dev)
> > +{
> > +	const struct iommu_ops *iommu_ops;
> > +
> > +	iommu_ops = virt_iommu_setup(dev);
> > +	if (IS_ERR_OR_NULL(iommu_ops)) {
> > +		int ret = PTR_ERR(iommu_ops);
> > +
> > +		if (ret == -EPROBE_DEFER || ret == 0)
> > +			return ret;
> > +		dev_err(dev, "error %d while setting up virt IOMMU\n", ret);
> > +		return 0;
> why do we return 0 here?

So we can fall back to another method (ACPI or DT) if available

> Besides
> 
> Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks!
Jean