linux-kernel - Re: [PATCH] PCI: cadence: Kconfig: change PCIE

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Message-ID: <7eaa4d917f7639913838abd4fd64ae8fe73a8cfc.camel@ti.com>
Date: Mon, 17 Nov 2025 11:35:39 +0530
From: Siddharth Vadapalli <s-vadapalli@...com>
To: Arnd Bergmann <arnd@...db.de>
CC: Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof
 Wilczyński <kwilczynski@...nel.org>, Manivannan Sadhasivam
	<mani@...nel.org>, Rob Herring <robh@...nel.org>, <bhelgaas@...gle.com>,
	"Chen Wang" <unicorn_wang@...look.com>, Kishon Vijay Abraham I
	<kishon@...nel.org>, <stable@...r.kernel.org>, <linux-pci@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<srk@...com>, <s-vadapalli@...com>
Subject: Re: [PATCH] PCI: cadence: Kconfig: change PCIE_CADENCE configs from
 tristate to bool

On Fri, 2025-11-14 at 08:03 +0100, Arnd Bergmann wrote:
> On Fri, Nov 14, 2025, at 06:47, Siddharth Vadapalli wrote:
> > On Thu, 2025-11-13 at 11:13 +0100, Arnd Bergmann wrote:
> > > On Thu, Nov 13, 2025, at 10:27, Siddharth Vadapalli wrote:
> 
> > Thank you for the suggestion. I think that the following Makefile changes
> > will be sufficient and Kconfig doesn't need to be modified:
> > 
> > diff --git a/drivers/pci/controller/cadence/Makefile
> > b/drivers/pci/controller/cadence/Makefile
> > index 5e23f8539ecc..1a97c9b249b8 100644
> > --- a/drivers/pci/controller/cadence/Makefile
> > +++ b/drivers/pci/controller/cadence/Makefile
> > @@ -4,4 +4,6 @@ obj-$(CONFIG_PCIE_CADENCE_HOST) += pcie-cadence-host.o
> >  obj-$(CONFIG_PCIE_CADENCE_EP) += pcie-cadence-ep.o
> >  obj-$(CONFIG_PCIE_CADENCE_PLAT) += pcie-cadence-plat.o
> >  obj-$(CONFIG_PCI_J721E) += pci-j721e.o
> > +pci_j721e-y := pci-j721e.o pcie-cadence.o
> >  obj-$(CONFIG_PCIE_SG2042_HOST) += pcie-sg2042.o
> > +pci_sg2042_host-y := pci-sg2042.o pcie-cadence.o
> > 
> > If either of PCI_J721E or SG2042_HOST is selected as a built-in module,
> > then pcie-cadence-host.c, pcie-cadence-ep.c and pcie-cadence.c drivers will
> > be built-in. If both PCI_J721E and SG2042_HOST are selected as loadable
> > modules, only then the library drivers will be enabled as loadable modules.
> > 
> > Please let me know what you think.
> 
> I don't think that the version above does what you want,
> this would build the pcie-cadence.o file into three separate
> modules and break in additional ways if a subset of them are
> built-in.
> 
> I would still suggest combining pcie-cadence{,-ep,-host}.o into
> one module that is used by the other drivers, as that would address
> the build failure you are observing.
> 
> An alternative would be to change the pcie-j721e.c file to only
> reference the host portion if host support is enabled for this
> driver.

While 'pcie-cadence.h' handles the case where 'PCIE_CADENCE_HOST' is not
defined:

#if IS_ENABLED(CONFIG_PCIE_CADENCE_HOST)
...
void cdns_pcie_host_disable(struct cdns_pcie_rc *rc);
...
#else
...
static inline void cdns_pcie_host_disable(struct cdns_pcie_rc *rc)
{
}
...
#endif

the issue occurs because PCIE_SG2042_HOST enables CONFIG_PCIE_CADENCE_HOST
but it is enabled as 'm'. As a result, the definition exists in pcie-
cadence-host.c that is built as a loadable module which is not accessible
by pci-j721e.c that is built-in.

I understand that the solution should be fixing the pci-j721e.c driver
rather than updating Kconfig or Makefile. Thank you for the feedback. I
will update the pci-j721e.c driver to handle the case that is triggering
the build error.

Regards,
Siddharth.