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Message-ID: <grouefwty7ub7xipgxyiph7dumtvoprcdsuq4f6d73pzpqu7pm@rdivadcdcyfy> Date: Thu, 6 Nov 2025 13:30:18 +0530 From: Manivannan Sadhasivam <mani@...nel.org> To: Siddharth Vadapalli <s-vadapalli@...com> Cc: lpieralisi@...nel.org, kwilczynski@...nel.org, robh@...nel.org, bhelgaas@...gle.com, jingoohan1@...il.com, christian.bruel@...s.st.com, krishna.chundru@....qualcomm.com, qiang.yu@....qualcomm.com, shradha.t@...sung.com, thippeswamy.havalige@....com, inochiama@...il.com, fan.ni@...sung.com, cassel@...nel.org, kishon@...nel.org, 18255117159@....com, rongqianfeng@...o.com, jirislaby@...nel.org, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, srk@...com Subject: Re: [PATCH v5 4/4] PCI: keystone: Add support to build as a loadable module On Thu, Nov 06, 2025 at 12:31:08PM +0530, Siddharth Vadapalli wrote: > On Wed, 2025-11-05 at 22:53 +0530, Manivannan Sadhasivam wrote: > > On Wed, Oct 29, 2025 at 01:34:52PM +0530, Siddharth Vadapalli wrote: > > > The 'pci-keystone.c' driver is the application/glue/wrapper driver for the > > > Designware PCIe Controllers on TI SoCs. Now that all of the helper APIs > > > that the 'pci-keystone.c' driver depends upon have been exported for use, > > > enable support to build the driver as a loadable module. > > > > > > Additionally, the functions marked by the '__init' keyword may be invoked: > > > a) After a probe deferral > > > OR > > > b) During a delayed probe - Delay attributed to driver being built as a > > > loadable module > > > > > > In both of the cases mentioned above, the '__init' memory will be freed > > > before the functions are invoked. This results in an exception of the form: > > > > > > Unable to handle kernel paging request at virtual address ... > > > Mem abort info: > > > ... > > > pc : ks_pcie_host_init+0x0/0x540 > > > lr : dw_pcie_host_init+0x170/0x498 > > > ... > > > ks_pcie_host_init+0x0/0x540 (P) > > > ks_pcie_probe+0x728/0x84c > > > platform_probe+0x5c/0x98 > > > really_probe+0xbc/0x29c > > > __driver_probe_device+0x78/0x12c > > > driver_probe_device+0xd8/0x15c > > > ... > > > > > > To address this, introduce a new function namely 'ks_pcie_init()' to > > > register the 'fault handler' while removing the '__init' keyword from > > > existing functions. > > > > > > Signed-off-by: Siddharth Vadapalli <s-vadapalli@...com> > > > --- > > > > > > v4: > > > https://lore.kernel.org/r/20251022095724.997218-5-s-vadapalli@ti.com/ > > > Changes since v4: > > > - To fix the build error on ARM32 platforms as reported at: > > > https://lore.kernel.org/r/202510281008.jw19XuyP-lkp@intel.com/ > > > patch 4 in the series has been updated by introducing a new config > > > named "PCI_KEYSTONE_TRISTATE" which allows building the driver as > > > a loadable module. Additionally, this newly introduced config can > > > be enabled only for non-ARM32 platforms. As a result, ARM32 platforms > > > continue using the existing PCI_KEYSTONE config which is a bool, while > > > ARM64 platforms can use PCI_KEYSTONE_TRISTATE which is a tristate, and > > > can optionally enabled loadable module support being enabled by this > > > series. > > > > > > Regards, > > > Siddharth. > > > > > > drivers/pci/controller/dwc/Kconfig | 15 +++-- > > > drivers/pci/controller/dwc/Makefile | 3 + > > > drivers/pci/controller/dwc/pci-keystone.c | 78 +++++++++++++---------- > > > 3 files changed, 59 insertions(+), 37 deletions(-) > > > > > > diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig > > > index 349d4657393c..c5bc2f0b1f39 100644 > > > --- a/drivers/pci/controller/dwc/Kconfig > > > +++ b/drivers/pci/controller/dwc/Kconfig > > > @@ -482,15 +482,21 @@ config PCI_DRA7XX_EP > > > to enable device-specific features PCI_DRA7XX_EP must be selected. > > > This uses the DesignWare core. > > > > > > +# ARM32 platforms use hook_fault_code() and cannot support loadable module. > > > config PCI_KEYSTONE > > > bool > > > > > > +# On non-ARM32 platforms, loadable module can be supported. > > > +config PCI_KEYSTONE_TRISTATE > > > + tristate > > > + > > > config PCI_KEYSTONE_HOST > > > - bool "TI Keystone PCIe controller (host mode)" > > > + tristate "TI Keystone PCIe controller (host mode)" > > > depends on ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST > > > depends on PCI_MSI > > > select PCIE_DW_HOST > > > - select PCI_KEYSTONE > > > + select PCI_KEYSTONE if ARM > > > + select PCI_KEYSTONE_TRISTATE if !ARM > > > > Wouldn't below change work for you? > > > > diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig > > index 349d4657393c..b1219e7136c9 100644 > > --- a/drivers/pci/controller/dwc/Kconfig > > +++ b/drivers/pci/controller/dwc/Kconfig > > @@ -486,8 +486,9 @@ config PCI_KEYSTONE > > bool > > > > config PCI_KEYSTONE_HOST > > - bool "TI Keystone PCIe controller (host mode)" > > + tristate "TI Keystone PCIe controller (host mode)" > > This doesn't alter the build of the pci-keystone.c driver. From the > existing Makefile, we have: > obj-$(CONFIG_PCI_KEYSTONE) += pci-keystone.o > implying that it is only CONFIG_PCI_KEYSTONE that determines whether the > pci-keystone.c driver is built as a loadable module or a built-in module. > Ah, I missed the fact that PCI_KEYSTONE_HOST is just used inside the driver and not in the Makefile. > > depends on ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST > > + default y if ARCH_KEYSTONE > > The default flag only specifies what should be selected by default, but it > doesn't prevent the user from attempting to built it as a loadable module > using menuconfig. Building the pci-keystone.c driver as a loadable module > (CONFIG_PCI_KEYSTONE set to 'm') will cause build errors for ARM32 > platforms due to the presence of hook_fault_code() which is __init code. > > The Kconfig and Makefile changes made by the patch do the following: > 1. Allow building the pci-keystone.c driver as a loadable module for non- > ARM32 platforms by introducing the PCI_KEYSTONE_TRISTATE config which is a > tristate unlike the existing PCI_KEYSTONE config which is a bool. > 2. Associate PCI_KEYSTONE with ARM32 platforms and associate > PCI_KEYSTONE_TRISTATE with non-ARM32 platforms to prevent users from > building the pci-keystone.c driver as a loadable module for ARM32 > platforms. > Ok. I don't have a better solution to this problem. So fine with me. - Mani -- மணிவண்ணன் சதாசிவம்
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