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    SubjectRe: [PATCH V4 3/4] ACPI/IORT: Ignore all errors except EPROBE_DEFER
    Hi Sricharan,

    On Thu, May 18, 2017 at 08:24:16PM +0530, Sricharan R wrote:
    > While deferring the probe of IOMMU masters, xlate and
    > add_device callbacks called from iort_iommu_configure
    > can pass back error values like -ENODEV, which means
    > the IOMMU cannot be connected with that master for real
    > reasons. Before the IOMMU probe deferral, all such errors
    > were ignored. Now all those errors are propagated back,
    > killing the master's probe for such errors. Instead ignore
    > all the errors except EPROBE_DEFER, which is the only one
    > of concern and let the master work without IOMMU, thus
    > restoring the old behavior.
    >
    > Fixes: 5a1bb638d567 ("drivers: acpi: Handle IOMMU lookup failure with deferred probing or error")
    > Signed-off-by: Sricharan R <sricharan@codeaurora.org>
    > ---
    > [V4] Added this patch newly.
    >
    > drivers/acpi/arm64/iort.c | 6 ++++++
    > 1 file changed, 6 insertions(+)
    >
    > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
    > index c5fecf9..16e101f 100644
    > --- a/drivers/acpi/arm64/iort.c
    > +++ b/drivers/acpi/arm64/iort.c
    > @@ -782,6 +782,12 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
    > if (err)
    > ops = ERR_PTR(err);
    >
    > + /* Ignore all other errors apart from EPROBE_DEFER */
    > + if (IS_ERR(ops) && (PTR_ERR(ops) != -EPROBE_DEFER)) {
    > + dev_dbg(dev, "Adding to IOMMU failed: %ld\n", PTR_ERR(ops));
    > + ops = NULL;
    > + }
    > +
    > return ops;
    > }
    >

    It is getting a bit convoluted. Is not it better to propagate the
    error back and let acpi_dma_configure() make a decision accordingly ?

    Something like:

    -- >8 --
    diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
    index e39ec7b..3a10d757 100644
    --- a/drivers/acpi/scan.c
    +++ b/drivers/acpi/scan.c
    @@ -1371,8 +1371,8 @@ int acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
    iort_set_dma_mask(dev);

    iommu = iort_iommu_configure(dev);
    - if (IS_ERR(iommu))
    - return PTR_ERR(iommu);
    + if (IS_ERR(iommu) && PTR_ERR(iommu) == -EPROBE_DEFER)
    + return -EPROBE_DEFER;

    size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
    /*
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      Last update: 2017-05-22 12:37    [W:3.346 / U:0.036 seconds]
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