On Mon, Dec 05, 2016 at 12:26:19PM +0000, Lorenzo Pieralisi wrote: > The introduction of acpi_dma_configure() allows to configure DMA > and related IOMMU for any device that is DMA capable. To achieve > that goal it ensures DMA masks are set-up to sane default values > before proceeding with IOMMU and DMA ops configuration. > > On x86/ia64 systems, through acpi_bind_one(), acpi_dma_configure() is > called for every device that has an ACPI companion, in that every device > is considered DMA capable on x86/ia64 systems (ie acpi_get_dma_attr() API), > which has the side effect of initializing dma masks also for > pseudo-devices (eg CPUs and memory nodes) and potentially for devices > whose dma masks were not set-up before the acpi_dma_configure() API was > introduced, which may have noxious side effects. > > Therefore, in preparation for IORT firmware specific DMA masks set-up, > wrap the default DMA masks set-up in acpi_dma_configure() inside an IORT > specific wrapper that reverts to a NOP on x86/ia64 systems, restoring the > default expected behaviour on x86/ia64 systems and keeping DMA default > masks set-up on IORT based (ie ARM) arch configurations. > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > Cc: Will Deacon <will.deacon@xxxxxxx> > Cc: Hanjun Guo <hanjun.guo@xxxxxxxxxx> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > Cc: Robin Murphy <robin.murphy@xxxxxxx> > Cc: Tomasz Nowicki <tn@xxxxxxxxxxxx> > Cc: Joerg Roedel <joro@xxxxxxxxxx> > Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> > Cc: Sricharan R <sricharan@xxxxxxxxxxxxxx> > --- > Joerg, > > pending Rafael's ACK on it, given the 4.10 release timing and that the > series is queued via the IOMMU tree please consider applying this patch to > your arm/smmu branch for 4.10, it is not fixing a bug but it is modifying > the x86/ia64 code path; I prefer preventing any issue related to default > dma masks on x86/ia64 so I hope it can get merged along with the rest of > the ACPI IORT SMMU series. > > Thanks a lot and apologies, > Lorenzo > > drivers/acpi/arm64/iort.c | 22 ++++++++++++++++++++++ > drivers/acpi/scan.c | 14 +------------- > include/linux/acpi_iort.h | 2 ++ > 3 files changed, 25 insertions(+), 13 deletions(-) Looks straightforward to me: Acked-by: Will Deacon <will.deacon@xxxxxxx> Joerg can probably just pick this on top of his queue. Will -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
