Jonathan Cameron wrote: > On Thu, 23 Jun 2022 21:19:34 -0700 > Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > > > From: Ben Widawsky <bwidawsk@xxxxxxxxxx> > > > > The region provisioning flow involves selecting interleave ways + > > granularity settings for a region, and then programming the decoder > > topology to meet those constraints, if possible. For example, root > > decoders set the minimum interleave ways + granularity for any hosted > > regions. > > > > Given decoder programming is not atomic and collisions can occur between > > multiple requesting regions userpace will be resonsible for conflict > > resolution and it needs these attributes to make those decisions. > > > > Signed-off-by: Ben Widawsky <bwidawsk@xxxxxxxxxx> > > [djbw: reword changelog, make read-only, add sysfs ABI documentaion] > > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > some comments on docs. > > > --- > > Documentation/ABI/testing/sysfs-bus-cxl | 23 +++++++++++++++++++++++ > > drivers/cxl/core/port.c | 23 +++++++++++++++++++++++ > > 2 files changed, 46 insertions(+) > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl > > index 85844f9bc00b..2a4e4163879f 100644 > > --- a/Documentation/ABI/testing/sysfs-bus-cxl > > +++ b/Documentation/ABI/testing/sysfs-bus-cxl > > @@ -215,3 +215,26 @@ Description: > > allocations are enforced to occur in increasing 'decoderX.Y/id' > > order and frees are enforced to occur in decreasing > > 'decoderX.Y/id' order. > > + > > + > > +What: /sys/bus/cxl/devices/decoderX.Y/interleave_ways > > +Date: May, 2022 > > +KernelVersion: v5.20 > > +Contact: linux-cxl@xxxxxxxxxxxxxxx > > +Description: > > + (RO) The number of targets across which this decoder's host > > + physical address (HPA) memory range is interleaved. The device > > + maps every Nth block of HPA (of size == > > + 'interleave_granularity') to consecutive DPA addresses. The > > + decoder's position in the interleave is determined by the > > + device's (endpoint or switch) switch ancestry. > > Perhaps make it clear what happens for host bridges (i.e. decoder position > in interleave defined by fixed memory window. Added: "For root decoders their interleave is specified by platform firmware and they only specify a downstream target order for host bridges". > > > + > > + > > +What: /sys/bus/cxl/devices/decoderX.Y/interleave_granularity > > +Date: May, 2022 > > +KernelVersion: v5.20 > > +Contact: linux-cxl@xxxxxxxxxxxxxxx > > +Description: > > + (RO) The number of consecutive bytes of host physical address > > + space this decoder claims at address N before awaint the next > > awaint? Surprised checkpatch did not flag this, or that I missed the checkpatch flag. > > > + address (N + interleave_granularity * intereleave_ways). > > interleave_ways > > Even knowing exactly what this is, I don't understand the docs so > perhaps reword this :) Reworded to: (RO) The number of consecutive bytes of host physical address space this decoder claims at address N before the decode rotates to the next target in the interleave at address N + interleave_granularity (assuming N is aligned to interleave_granularity).
