Re: [PATCH v2 1/4] iommu/arm-smmu-v3: Clean up address masking

[Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>]

Hi Robin,

On Thu, Dec 14, 2017 at 04:58:50PM +0000, Robin Murphy wrote:
> Before trying to add the SMMUv3.1 support for 52-bit addresses, make
> things bearable by cleaning up the various address mask definitions to
> use GENMASK_ULL() consistently. The fact that doing so reveals (and
> fixes) a latent off-by-one in Q_BASE_ADDR_MASK only goes to show what a
> jolly good idea it is...
> 
> Tested-by: Nate Watterson <nwatters-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> Signed-off-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
> ---
> 
> v2: Clean up one more now-unnecessary linewrap
> 
>  drivers/iommu/arm-smmu-v3.c | 53 ++++++++++++++++++---------------------------
>  1 file changed, 21 insertions(+), 32 deletions(-)

Whilst I agree that using GENMASK is better, this patch does mean that the
driver is (more) inconsistent with its _MASK terminology in that you can't
generally tell whether a definition that ends in _MASK is shifted or not,
and this isn't even consistent for fields within the same register.

Should we be using GENMASK/BIT for all fields instead and removing all of
the _SHIFT definitions?

Will