Re: [PATCH 0/4] MIPS: ralink: pci: driver for Pcie controller in MT7621 SoCs

From: Sergio Paracuellos <sergio.paracuellos@gmail.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: "Pali Rohár" <pali@kernel.org>,
	"Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
	lorenzo.pieralisi@arm.com,
	"open list:MIPS" <linux-mips@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"John Crispin" <john@phrozen.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	linux-staging@lists.linux.dev,
	"Greg KH" <gregkh@linuxfoundation.org>,
	NeilBrown <neil@brown.name>,
	"Ilya Lipnitskiy" <ilya.lipnitskiy@gmail.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-pci@vger.kernel.org
Subject: Re: [PATCH 0/4] MIPS: ralink: pci: driver for Pcie controller in MT7621 SoCs
Date: Fri, 4 Jun 2021 23:15:56 +0200	[thread overview]
Message-ID: <CAMhs-H98efm9bCL4ff85mcbKReBVyGsVmMw-YXRL_FXzPTyw4Q@mail.gmail.com> (raw)
In-Reply-To: <20210604194328.GA2230062@bjorn-Precision-5520>

Hi Bjorn,

On Fri, Jun 4, 2021 at 9:43 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Mon, May 31, 2021 at 03:18:45PM +0200, Pali Rohár wrote:
> > On Friday 21 May 2021 12:23:38 Thomas Bogendoerfer wrote:
> > > On Wed, May 19, 2021 at 11:18:36PM +0200, Sergio Paracuellos wrote:
> > > > On Wed, May 19, 2021 at 10:36 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > > > > But most of the similar drivers are in drivers/pci/controller/, where
> > > > > I think it's easier to keep them up to date with changes in the PCI
> > > > > core.  Have you considered putting this one there?
> > > >
> > > > Most pci drivers in 'arch/mips/pci' are still using PCI_LEGACY stuff.
> > > > In contrast mt7621-pci is using current pci generic apis but even most
> > > > of the code is generic enough, there is one remaining thing which
> > > > depends on mips architecture which is the iocu region configuration
> > > > which must be done in the driver itself. This is the only reason to
> > > > move this driver into 'arch/mips/pci' instead of
> > > > 'drivers/pci/controller/'. So... I am all ears to listen to
> > > > suggestions for the proper place for this driver. Thomas, do you have
> > > > any thoughts on this?
> > >
> > > I tried to put a pci-xtalk driver into drivers/pci/controller, but
> > > Lorenzo didn't want it there for being MIPS and not DT based. So this
> > > one is DT based, but still MIPS. I'm perfectly fine putting this
> > > driver into drivers/pci/controller/
> >
> > In my personal opinion this driver could go into drivers/pci/controller/
>
> I'm not sure exactly what "PCI_LEGACY" above refers to.

I meant most of the drivers there are not using current generic pci
apis but still using pci legacy ones.

>
> I don't see any direct #includes of arch/mips in the driver.  I do see
> that it uses mips_cps_numiocu(), which is certainly MIPS-specific.

Yes, mips_cps_numiocu is the only stuff needed and arch specific used
by this driver.

>
> But we do have some things in drivers/pci/controller/ that only build
> on certain arches, enforced mostly by Kconfig rules, so I think you
> could do that.  We try to make so things can at least be *compiled* on
> any arch, but I know that's not always possible.
>
> So I think it would be useful to put this in drivers/pci/controller/
> somewhere because it will make it easier to see common patterns and
> refactoring opportunities.

Ok, so I will move the driver into 'drivers/pci/controller/' in v2.

Thanks,
    Sergio Paracuellos
>
> Bjorn