On Tue, 2018-06-12 at 11:35 +0300, Andy Shevchenko wrote: > On Tue, Jun 12, 2018 at 3:01 AM, Benjamin Herrenschmidt > <b...@kernel.crashing.org> wrote: > > There are still quite a few cases where a device might want to get to a > > different node of the device-tree, obtain the resources and map them. > > > > Drivers doing that currently open code the whole thing, which is error > > proe. > > prone > > > > > We have of_iomap() and of_io_request_and_map() but they both have > > shortcomings, > > such as not returning the size of the resource found (which can be > > necessary) > > and not being "managed". > > > > This adds a devm_of_iomap() that provides all of these and should probably > > replace uses of the above in most drivers. > > It feels like a wrong approach. > Can OF graph help here? Would it be better approach?
I don't quite understand what your objection is nor what "OF graph" is... This is a direct replacement for the open coded equivalent that a number of drivers do, almost always without using devm_* or forgetting to request the resources etc... Ie, a less bug-prone tool in the toolbox. So there's a real use case here. In fact a driver I'm going to submit soon uses it, which is why I wrote it in the first place, rather than adding yet another open-coded case. And to reply to the inevitable next reaction, NO this is not a case for creating yet another 237 layers of abstractions. Sometimes, a driver needs to directly access (no regmap overhead please) some regions represented by a specific DT node (it could be a child of the device for example representing a portion of its register space, or it could be a separate piece of HW that needs to be used by the device but doesn't fit in any abstract model and shouldn't). Ben.