Re: [PATCH 3/3] ACPI: Change NFIT driver to set PMEM type to iomem entry

On Wed, Feb 17, 2016 at 10:00 AM, Toshi Kani <toshi.kani(a)hpe.com&gt; wrote: > On Tue, 2016-02-16 at 19:00 -0700, Toshi Kani wrote: > > On Fri, 2016-02-12 at 15:32 -0800, Dan Williams wrote: > > > On Fri, Feb 12, 2016 at 2:30 PM, Toshi Kani <toshi.kani(a)hpe.com&gt; > > > wrote:

> > Here are three options I can think of. > > > > 1) Set pmem type to "reserved" (This patch-set) > >  - Add a new iomem_set_desc(), which sets a given type to a top-level > > entry.  Change the ACPI NFIT driver to call it to set pmem type to > > "reserved" entry. > >  - region_intersects() finds a pmem entry by checking top-level > > entries (no change). > > > > 2) Change region_intersects() to check children's type > >  - Add a new request_region_ext(), which is an extension to > > request_region() to allow specifying a type of resource.  It puts a > > new child entry under "reserved".  Change the pmem driver to call > > this func. > >  - Change region_intersects() to check children's type for finding > > this child pmem entry. > > > > 3) Pmem driver to call insert_resource() > >  - Change the pmem driver to call insert_resource(), which puts a new > > pmem entry as the parent of "reserved". > >  - region_intersects() finds a pmem entry by checking top-level > > entries (no change). > >  - Add a new release_resource_self(), which releases a given entry > > and keeps its children if any.  Change the pmem driver to call it for > > release. > > Thinking further, 3) needs to be modified as follows.  insert_resource( > ) should only be allowed for producers of resource (ex. nfit), not > consumers (ex. pmem).  It also needs to export insert_resource(). > > 3) NFIT driver to call insert_resource() >  - Change the ACPI nfit driver to call insert_resource() when a target > range is not marked as PMEM (i.e. "reserved") or not present in iomem. >  This puts a new PMEM entry as the parent of "reserved". >  - region_intersects() finds a pmem entry by checking top-level entries > (no change). >  - Add a new release_resource_self(), which releases a given entry and > keeps its children if any.  Change the nfit driver to call it for > release. > > > This patch-set implements 1).  The pmem type is set to "reserved" for > > its life-cycle.  This option is simplest. > > > > For 2), the changes to region_intersects() may be too complex for > > maintenance. > > I should have said "region_intersects() may be overly complicated for > this purpose and maintenance". > > > Here are a few examples when region_intersects() is called > > with addr [1-10] where iomem has entry P and its children. > > > > Case A: P is fully covered by children C1 & C2.  region_intersects() > > ignores P's type, but checks C1 and C2's. > > > >   P [1-10] + C1 [1-5] > >            + C2 [6-10] > > > > Case B: C2 is fully covered by C3, but P is not.  region_intersects() > > ignores C2's type, but checks P, C1, C3's. > > > >   P [1-10] + C1 [1-2] > >            + C2 [6-10] + C3 [6-10] > > > > I think region_intersects() will need to construct a flat table from > > the tree while making recursive calls to walk thru all children. > > > > 3) is similar to 2), but avoids the changes to region_intersects() > > since insert_resource() inserts a new entry as the parent to > > "reserved". > > 3) is actually similar to 1) as both options change the producer side. > > >  However, a new interface is necessary to put "reserved" back to top- > > level when releasing the added entry. > > > > My recommendation is go with either 1) or 3).  What do you think? > > I think we should modify the producer side, so 1) or 3) are still my > recommendation. > I think 3 is the most promising option.  It aligns the acpi/nfit driver closer with the acpi/pci_root driver that is also doing insert_resource() for each root bridge, and removing those resources when the bridge is disabled/removed. I'd still want to maintain the ability of nfit to be built as a module, so we would need to split the resource registration into a separate built-in object file from nfit.ko.