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    SubjectRe: [PATCH v2] of: Fix "dma-ranges" handling for bus controllers
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    On 2022-09-30 20:39, Rob Herring wrote:
    > On Thu, 29 Sep 2022 13:48:38 +0100, Robin Murphy wrote:
    >> Commit 951d48855d86 ("of: Make of_dma_get_range() work on bus nodes")
    >> relaxed the handling of "dma-ranges" for any leaf node on the assumption
    >> that it would still represent a usage error for the property to be
    >> present on a non-bus leaf node. However there turns out to be a fiddly
    >> case where a bus also represents a DMA-capable device in its own right,
    >> such as a PCIe root complex with an integrated DMA engine on its
    >> platform side. In such cases, "dma-ranges" translation is entirely valid
    >> for devices discovered behind the bus, but should not be erroneously
    >> applied to the bus controller device itself which operates in its
    >> parent's address space. Fix this by restoring the previous behaviour for
    >> the specific case where a device is configured via its own OF node,
    >> since it is logical to assume that a device should never represent its
    >> own parent bus.
    >>
    >> Reported-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
    >> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
    >> ---
    >>
    >> v2: Fix !HAS_DMA build error
    >>
    >> drivers/of/address.c | 4 +++-
    >> drivers/of/device.c | 9 ++++++++-
    >> drivers/of/of_private.h | 5 +++++
    >> 3 files changed, 16 insertions(+), 2 deletions(-)
    >>
    >
    > Applied, thanks!
    >
    > I assume this was not tagged with Fixes or stable because there is not
    > yet a user that needs it? I didn't add it either because I'm a bit
    > worried about regressions and applying this just before the merge
    > window. So send it to stable later if anyone cares.

    Indeed this was only brought to light by a patch series that Serge is
    working on, so although it's technically a fix I don't believe it's
    affecting any in-tree users yet, thus doesn't warrant backporting.

    Cheers,
    Robin.

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