On Thu, Mar 11, 2021 at 9:48 AM Arnd Bergmann <arnd@xxxxxxxxxx> wrote: > > On Thu, Mar 11, 2021 at 5:10 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > On Thu, Mar 11, 2021 at 2:12 AM Arnd Bergmann <arnd@xxxxxxxxxx> wrote: > > > On Wed, Mar 10, 2021 at 6:01 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > > Ok, makes sense. > > > > > > Conceptually, I'd like to then see a check that verifies that the > > > property is only set for nodes whose parent also has it set, since > > > that is how AXI defines it: A bus can wait for the ack from its > > > child node, or it can acknowledge the write to its parent early. > > > However, this breaks down as soon as a bus does the early ack: > > > all its children by definition use posted writes (as seen by the > > > CPU), even if they wait for stores that come from other masters. > > > > > > Does this make sense to you? > > > > BTW, I don't think it's clear in this thread, but the current > > definition proposed for the spec[1] and schema is 'nonposted-mmio' is > > specific to 'simple-bus'. I like this restriction and we can expand > > where 'nonposted-mmio' is allowed later if needed. > > That sounds ok, as long as we can express everything for the mac > at the moment. Do we need to explicitly add a description to allow > the property in the root node in addition to simple-bus to be able > to enforce the rule about parent buses also having it? IMO it should not be allowed in the root node. That's a failure to define a bus node. Also, would that mean your memory has to be non-posted!? Rob
