On Wed, Nov 29, 2023 at 05:43:00PM +0000, Robin Murphy wrote: > Return the Root Complex/Named Component memory address size limit as an > inclusive limit value, rather than an exclusive size. This saves us > having to special-case 64-bit overflow, and simplifies our caller too. > > Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx> > --- > drivers/acpi/arm64/dma.c | 9 +++------ > drivers/acpi/arm64/iort.c | 18 ++++++++---------- > include/linux/acpi_iort.h | 4 ++-- > 3 files changed, 13 insertions(+), 18 deletions(-) [...] > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c > index 6496ff5a6ba2..eb64d8e17dd1 100644 > --- a/drivers/acpi/arm64/iort.c > +++ b/drivers/acpi/arm64/iort.c > @@ -1367,7 +1367,7 @@ int iort_iommu_configure_id(struct device *dev, const u32 *input_id) > { return -ENODEV; } > #endif > > -static int nc_dma_get_range(struct device *dev, u64 *size) > +static int nc_dma_get_range(struct device *dev, u64 *limit) > { > struct acpi_iort_node *node; > struct acpi_iort_named_component *ncomp; > @@ -1384,13 +1384,12 @@ static int nc_dma_get_range(struct device *dev, u64 *size) > return -EINVAL; > } > > - *size = ncomp->memory_address_limit >= 64 ? U64_MAX : > - 1ULL<<ncomp->memory_address_limit; > + *limit = (1ULL << ncomp->memory_address_limit) - 1; The old code handled 'ncomp->memory_address_limit >= 64' -- why is it safe to drop that? You mention it in the cover letter, so clearly I'm missing something! > > return 0; > } > > -static int rc_dma_get_range(struct device *dev, u64 *size) > +static int rc_dma_get_range(struct device *dev, u64 *limit) > { > struct acpi_iort_node *node; > struct acpi_iort_root_complex *rc; > @@ -1408,8 +1407,7 @@ static int rc_dma_get_range(struct device *dev, u64 *size) > return -EINVAL; > } > > - *size = rc->memory_address_limit >= 64 ? U64_MAX : > - 1ULL<<rc->memory_address_limit; > + *limit = (1ULL << rc->memory_address_limit) - 1; Same thing here. Will