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@xxxxxxx> wrote: > > > On Fri, 2016-02-12 at 11:41 -0800, Dan Williams wrote: > > > > On Tue, Feb 2, 2016 at 10:55 AM, Toshi Kani <toshi.kani@xxxxxxx> > > > > wro > : > > > > Hmm, if we set the type on driver load, should we clear the type on > > > > driver unload? > > > > > > I think this type update should stay for the life-cycle of this iomem > > > entry itself since this range is PMEM even after the driver is > > > unloaded. This is an extension of the boot-time iomem table > > > initialization from e820/EFI, which allows ACPI to set a correct > > > type. This is independent from driver's resource allocations. > > > > > > > Actually it might be more straightforward to specify a type at > > > > request_region() time. That way it gets released at > > > > release_region(). We're already setting a resource name at > > > > request_region time, adding a type annotation at the time seems > > > > appropriate. > > > > > > I first considered simply setting "namespaceX.X" as PMEM. However, > > > region_intersects() and its friends only check the top-level entries, > > > not their children, of the iomem table. And I think a child should > > > have the same type as the parent as I fixed it in patch 1/3. > > > > Did we investigate updating region_intersects() to check children? > > When a child sub-divides a region with different types it may be the > > wrong answer to check the parent. Is there a problem with moving > > checking to the child? > > 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. Thanks, -Toshi -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
