From: Bjorn Helgaas <helgaas@kernel.org>
To: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Yanteng Si <siyanteng01@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
bcm-kernel-feedback-list@broadcom.com,
Yanteng Si <siyanteng@loongson.cn>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Rob Herring <robh@kernel.org>,
kw@linux.com, Bjorn Helgaas <bhelgaas@google.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
Philipp Zabel <p.zabel@pengutronix.de>,
linux-pci <linux-pci@vger.kernel.org>,
linux-arm-kernel@lists.infradead.org,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
"open list:MIPS" <linux-mips@vger.kernel.org>,
chenhuacai@kernel.org, sterlingteng@gmail.com,
Linux Next Mailing List <linux-next@vger.kernel.org>
Subject: Re: [PATCH v2 2/3] MIPS: cm/cpc: export some missing symbols to be able to use them from driver code
Date: Fri, 29 Oct 2021 14:47:51 -0500 [thread overview]
Message-ID: <20211029194751.GA349935@bhelgaas> (raw)
In-Reply-To: <CAMhs-H8bjOkwfnYqdhWuwA8vt18naW3DABYN-EyW-gDB2cP7JA@mail.gmail.com>
On Fri, Oct 29, 2021 at 09:37:53PM +0200, Sergio Paracuellos wrote:
> On Fri, Oct 29, 2021 at 8:49 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > On Fri, Oct 29, 2021 at 07:28:47AM +0200, Sergio Paracuellos wrote:
> > > On Thu, Oct 28, 2021 at 10:47 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > > > On Thu, Oct 28, 2021 at 11:59:17AM +0200, Sergio Paracuellos wrote:
> > > > > On Thu, Oct 28, 2021 at 11:34 AM Sergio Paracuellos
> > > > > <sergio.paracuellos@gmail.com> wrote:
> > > > > > On Thu, Oct 28, 2021 at 11:24 AM Thomas Bogendoerfer
> > > > > > <tsbogend@alpha.franken.de> wrote:
> > > > > > > On Thu, Oct 28, 2021 at 06:11:18AM +0200, Sergio Paracuellos wrote:
> > > > > > > > On Thu, Oct 28, 2021 at 6:05 AM Yanteng Si <siyanteng01@gmail.com> wrote:
> > > > > > > > >
> > > > > > > > > Since commit 2bdd5238e756 ("PCI: mt7621: Add MediaTek MT7621 PCIe host controller driver")
> > > > > > > > > the MT7621 PCIe host controller driver is built as a module but modpost complains once these
> > > > > > > > > drivers become modules.
> > > > > > > > >
> > > > > > > > > ERROR: modpost: "mips_cm_unlock_other" [drivers/pci/controller/pcie-mt7621.ko] undefined!
> > > > > > > > > ERROR: modpost: "mips_cpc_base" [drivers/pci/controller/pcie-mt7621.ko] undefined!
> > > > > > > > > ERROR: modpost: "mips_cm_lock_other" [drivers/pci/controller/pcie-mt7621.ko] undefined!
> > > > > > > > > ERROR: modpost: "mips_cm_is64" [drivers/pci/controller/pcie-mt7621.ko] undefined!
> > > > > > > > > ERROR: modpost: "mips_gcr_base" [drivers/pci/controller/pcie-mt7621.ko] undefined!
> > > > > > > > >
> > > > > > > > > Let's just export them.
> > > > > > > > >
> > > > > > > > > Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
> > > > > > > > > ---
> > > > > > > > > arch/mips/kernel/mips-cm.c | 5 +++++
> > > > > > > > > arch/mips/kernel/mips-cpc.c | 1 +
> > > > > > > > > 2 files changed, 6 insertions(+)
> > > > > > > > >
> > > > > > > >
> > > > > > > > Reviewed-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
> > > > > > >
> > > > > > > could we instead make the pcie-mt761 driver non modular ? Exporting
> > > > > > > all MIPS specific stuff for just making an essential driver modular
> > > > > > > doesn't IMHO make much sense.
> > > > > >
> > > > > > The driver is modular because I have been advised other times that new
> > > > > > drivers should be able to be compiled as modules and we should avoid
> > > > > > using 'bool' in Kconfig for new drivers. That's the only reason. I am
> > > > > > also always including as 'y' the driver since for me not having pci in
> > > > > > my boards has no sense... I am ok in changing Kconfig to be 'bool'
> > > > > > instead of 'tristate', but I don't know what should be the correct
> > > > > > thing to do in this case. Thoughts?
> > > > >
> > > > > I guess we also want the driver to at least be compile tested in
> > > > > 'allmodconfig' and other similars...15692a80d949
> > > >
> > > > Sounds like the systems that actually use this driver require it to be
> > > > built-in, and the only benefit of exporting these symbols is that we
> > > > would get better compile test coverage.
> > > >
> > > > If that's the case, I agree that it's better to just make it
> > > > non-modular.
> > >
> > > I agree and that was my reasoning for sending a patch to also convert
> > > to bool the phy driver that this PCIe controller uses. When the pull
> > > request was sent from Vinod to Greg, Greg refused to take it because
> > > of that commit and the commit was reverted and a new pull request was
> > > sent including this revert. This is commit 15692a80d949 ("phy: Revert
> > > "phy: ralink: Kconfig: convert mt7621-pci-phy into 'bool'""). Because
> > > of this I also changed the PCIe controller Kconfig from bool to
> > > tristate when I sent v3 of the series which at the end were the ones
> > > that was finally taken. There are also other ralink related symbols
> > > that have been exported to allow to compile other drivers as a
> > > modules, like the watchdog. See the commit fef532ea0cd8 ("MIPS:
> > > ralink: export rt_sysc_membase for rt2880_wdt.c"). So, as I said, I
> > > agree and I am using the driver as if it were a bool and also ralink
> > > systems normally require all drivers built-in, but I think we have to
> > > take into account also the "historical facts" here. In any case,
> > > Bjorn, let me know if you want me to send whatever patch might be
> > > needed.
> >
> > I didn't see the conversation with Greg, so I don't know the whole
> > story.
>
> Here it is: https://www.spinics.net/lists/kernel/msg3986821.html
>
> > For pcie-mt7621.c, it looks like the only problem is
> > setup_cm_memory_region(), which does a little coherency-related stuff.
> > If we could move that to arch/mips, we could still make this tristate.
>
> Yes, the only mips specific function used in the driver is
> 'setup_cm_memory_region()'.
>
> > One way might be to implement a pcibios_root_bridge_prepare() for mips
> > and put the setup_cm_memory_region() stuff in there. It's not *ideal*
> > because that's a strong/weak function arrangement that doesn't allow
> > for multiple host bridges, but that's probably not an issue here.
> >
> > If we can't do that, I think making it bool is probably the right
> > answer, but it would be worth a brief comment in the commit log to
> > explain the issue.
>
> Do you mean to implement 'pcibios_root_bridge_prepare()' for MIPS
> ralink? I guess this means to parse device tree and so on only to get
> memory range addresses to be added to the MIPS I/O coherence regions
> to make things work and then re-parse it again in the driver to do the
> proper PCI setup... We end up in an arch generic driver but at the end
> this controller is only present in ralink MIPS, so I am not sure that
> implementing 'pcibios_root_bridge_prepare()' is worthy here... I can
> explore and try to implement it if you think that it really makes
> sense... but, IMHO if this is the case, just making it bool looks like
> the correct thing to do.
It should be trivial to put the contents of setup_cm_memory_region()
into a ralink function called pcibios_root_bridge_prepare().
pcibios_root_bridge_prepare() is called with the same "struct
pci_host_bridge *" argument as setup_cm_memory_region(), and it's
called slightly later, so the window resources are already set up, so
no DT parsing is required. It looks like a simple move and rename to
me.
Bjorn
next prev parent reply other threads:[~2021-10-29 19:47 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-28 4:04 [PATCH v2 0/3] MIPS: Fix build error ERROR: modpost: Yanteng Si
2021-10-28 4:04 ` [PATCH v2 1/3] PCI: mt7621: Add MODULE_* macros to MT7621 PCIe host controller driver Yanteng Si
2021-10-28 4:04 ` [PATCH v2 2/3] MIPS: cm/cpc: export some missing symbols to be able to use them from driver code Yanteng Si
2021-10-28 4:11 ` Sergio Paracuellos
2021-10-28 9:23 ` Thomas Bogendoerfer
2021-10-28 9:34 ` Sergio Paracuellos
2021-10-28 9:59 ` Sergio Paracuellos
2021-10-28 20:47 ` Bjorn Helgaas
2021-10-29 5:28 ` Sergio Paracuellos
2021-10-29 18:49 ` Bjorn Helgaas
2021-10-29 19:37 ` Sergio Paracuellos
2021-10-29 19:47 ` Bjorn Helgaas [this message]
2021-10-29 20:27 ` Sergio Paracuellos
2021-10-30 5:21 ` Sergio Paracuellos
2021-10-30 5:38 ` Sergio Paracuellos
2021-11-07 7:00 ` Sergio Paracuellos
2021-11-09 22:41 ` Bjorn Helgaas
2021-11-10 6:00 ` Sergio Paracuellos
2021-11-15 8:17 ` Sergio Paracuellos
2021-10-28 4:04 ` [PATCH v2 3/3] MIPS: traps: export a missing symbols to be able to use it " Yanteng Si
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