Re: [PATCH v3 00/27] Add support for OpenCAPI Persistent Memory devices

[Dan Williams]

On Tue, Feb 25, 2020 at 4:14 PM Alastair D'Silva <alastair@xxxxxxxxxxx> wrote:
>
> On Mon, 2020-02-24 at 17:51 +1100, Oliver O'Halloran wrote:
> > On Mon, Feb 24, 2020 at 3:43 PM Alastair D'Silva <
> > alastair@xxxxxxxxxxx> wrote:
> > > On Sun, 2020-02-23 at 20:37 -0800, Matthew Wilcox wrote:
> > > > On Mon, Feb 24, 2020 at 03:34:07PM +1100, Alastair D'Silva wrote:
> > > > > V3:
> > > > >   - Rebase against next/next-20200220
> > > > >   - Move driver to arch/powerpc/platforms/powernv, we now
> > > > > expect
> > > > > this
> > > > >     driver to go upstream via the powerpc tree
> > > >
> > > > That's rather the opposite direction of normal; mostly drivers
> > > > live
> > > > under
> > > > drivers/ and not in arch/.  It's easier for drivers to get
> > > > overlooked
> > > > when doing tree-wide changes if they're hiding.
> > >
> > > This is true, however, given that it was not all that desirable to
> > > have
> > > it under drivers/nvdimm, it's sister driver (for the same hardware)
> > > is
> > > also under arch, and that we don't expect this driver to be used on
> > > any
> > > platform other than powernv, we think this was the most reasonable
> > > place to put it.
> >
> > Historically powernv specific platform drivers go in their respective
> > subsystem trees rather than in arch/ and I'd prefer we kept it that
> > way. When I added the papr_scm driver I put it in the pseries
> > platform
> > directory because most of the pseries paravirt code lives there for
> > some reason; I don't know why. Luckily for me that followed the same
> > model that Dan used when he put the NFIT driver in drivers/acpi/ and
> > the libnvdimm core in drivers/nvdimm/ so we didn't have anything to
> > argue about. However, as Matthew pointed out, it is at odds with how
> > most subsystems operate. Is there any particular reason we're doing
> > things this way or should we think about moving libnvdimm users to
> > drivers/nvdimm/?
> >
> > Oliver
>
>
> I'm not too fussed where it ends up, as long as it ends up somewhere :)
>
> From what I can tell, the issue is that we have both "infrastructure"
> drivers, and end-device drivers. To me, it feels like drivers/nvdimm
> should contain both, and I think this feels like the right approach.
>
> I could move it back to drivers/nvdimm/ocxl, but I felt that it was
> only tolerated there, not desired. This could be cleared up with a
> response from Dan Williams, and if it is indeed dersired, this is my
> preferred location.

Apologies if I gave the impression it was only tolerated. I'm ok with
drivers/nvdimm/ocxl/, and to the larger point I'd also be ok with a
drivers/{acpi => nvdimm}/nfit and {arch/powerpc/platforms/pseries =>
drivers/nvdimm}/papr_scm.c move as well to keep all the consumers of
the nvdimm related code together with the core.