On 28/03/17 16:00, Rob Herring wrote: > On Fri, Mar 10, 2017 at 12:30:57AM +0530, Sricharan R wrote: >> From: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> >> >> Failures to look up an IOMMU when parsing the DT iommus property need to >> be handled separately from the .of_xlate() failures to support deferred >> probing. >> >> The lack of a registered IOMMU can be caused by the lack of a driver for >> the IOMMU, the IOMMU device probe not having been performed yet, having >> been deferred, or having failed. >> >> The first case occurs when the device tree describes the bus master and >> IOMMU topology correctly but no device driver exists for the IOMMU yet >> or the device driver has not been compiled in. Return NULL, the caller >> will configure the device without an IOMMU. >> >> The second and third cases are handled by deferring the probe of the bus >> master device which will eventually get reprobed after the IOMMU. >> >> The last case is currently handled by deferring the probe of the bus >> master device as well. A mechanism to either configure the bus master >> device without an IOMMU or to fail the bus master device probe depending >> on whether the IOMMU is optional or mandatory would be a good >> enhancement. >> >> Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> >> Signed-off-by: Laurent Pichart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> >> Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx> >> --- >> drivers/base/dma-mapping.c | 5 +++-- >> drivers/iommu/of_iommu.c | 4 ++-- >> drivers/of/device.c | 7 ++++++- >> include/linux/of_device.h | 9 ++++++--- >> 4 files changed, 17 insertions(+), 8 deletions(-) > > Maybe it is the same issue reported for VFIO, but virtio-pci is broken > with v8 of this series. Bisecting blames this commit which looks like it > hasn't changeed. v8 managed to break *all* PCI devices which didn't have an associated "iommu-map". The problem was actually in patch 2 (and is fixed in this version), but it only hit at this point once we start propagating the erroneous error code back to the driver probe. Robin. > > Rob > > P.S. Doesn't look like you have copied the DT maintainers nor list for > the DT changes. >
