On Thu, May 20, 2021 at 10:01:23AM +0100, Jon Hunter wrote:
> Commit 7f100744749e ("PCI: tegra: Add Tegra194 MCFG quirks for ECAM
> errata") caused a few build regressions for the Tegra194 PCIe driver
> which are:
>
> 1. The Tegra194 PCIe driver can no longer be built as a module. This
> was caused by removing the Makefile entry to build the pcie-tegra.c
> based upon the CONFIG_PCIE_TEGRA194 option. Therefore, restore this
> so that we can build the driver as a module if ACPI support is not
> enabled in the kernel.
I'm not sure what "if ACPI support is not enabled in the kernel" is
telling me. Does it mean that we can only build tegra194 as a module
if ACPI is not enabled? I don't think so (at least, I don't think
Kconfig enforces that).
Should the "if ACPI support is not enabled ..." part just be dropped?
I assume it should be possible to build the kernel with ACPI enabled
and with pcie-tegra194 as a module?
> 2. If CONFIG_PCIE_TEGRA194 is configured to build the driver as a
> module, at the same time that CONFIG_ACPI and CONFIG_PCI_QUIRKS are
> selected to build the driver into the kernel, then the necessary
> functions in the driver to probe and remove the device when booting
> with device-tree and not compiled into to the driver. This prevents
> the PCIe devices being probed when booting with device-tree. Fix this
> by using the IS_ENABLED() macro.
The #ifdef vs IS_ENABLED() difference is kind of subtle and I have to
figure it out every time. Maybe something like this?
7f100744749e ("PCI: tegra: Add Tegra194 MCFG quirks for ECAM
errata") added "#ifdef CONFIG_PCIE_TEGRA194" around the native
driver.
But if we set CONFIG_PCIE_TEGRA194=m to build the driver as a
module, autoconf.h contains "#define CONFIG_PCIE_TEGRA194_MODULE 1"
(not "#define CONFIG_PCIE_TEGRA194 1"), so the #ifdef excludes the
driver.
Instead, use "IS_ENABLED(CONFIG_PCIE_TEGRA194)", which checks for
either CONFIG_PCIE_TEGRA194 or CONFIG_PCIE_TEGRA194_MODULE.
> 3. The below build warnings to be seen with particular kernel
> configurations. Fix these by adding the necessary guards around these
> variable definitions.
>
> drivers/pci/controller/dwc/pcie-tegra194.c:259:18: warning:
> ‘event_cntr_data_offset’ defined but not used [-Wunused-const-variable=]
> drivers/pci/controller/dwc/pcie-tegra194.c:250:18: warning:
> ‘event_cntr_ctrl_offset’ defined but not used [-Wunused-const-variable=]
> drivers/pci/controller/dwc/pcie-tegra194.c:243:27: warning:
> ‘pcie_gen_freq’ defined but not used [-Wunused-const-variable=]
>
> Fixes: 7f100744749e ("PCI: tegra: Add Tegra194 MCFG quirks for ECAM errata")
> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
This is a candidate for v5.13, since we merged 7f100744749e for
v5.13-rc1.
> ---
> drivers/pci/controller/dwc/Makefile | 1 +
> drivers/pci/controller/dwc/pcie-tegra194.c | 6 +++++-
> 2 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
> index eca805c1a023..f0d1e2d8c022 100644
> --- a/drivers/pci/controller/dwc/Makefile
> +++ b/drivers/pci/controller/dwc/Makefile
> @@ -32,6 +32,7 @@ obj-$(CONFIG_PCIE_UNIPHIER_EP) += pcie-uniphier-ep.o
> # depending on whether ACPI, the DT driver, or both are enabled.
>
> obj-$(CONFIG_PCIE_AL) += pcie-al.o
> +obj-$(CONFIG_PCIE_TEGRA194) += pcie-tegra194.o
> obj-$(CONFIG_PCI_HISI) += pcie-hisi.o
It sounds like the interesting case is this:
CONFIG_ARM64=y
CONFIG_ACPI=y
CONFIG_PCI_QUIRKS=y
CONFIG_PCIE_TEGRA194=m
I don't know how this works in this case:
obj-$(CONFIG_PCIE_TEGRA194) += pcie-tegra194.o
obj-$(CONFIG_ARM64) += pcie-tegra194.o
We want tegra194_acpi_init() and the rest of the ECAM quirk to be
compiled into the static kernel. And we want tegra_pcie_dw_probe(),
tegra_pcie_dw_remove(), etc, compiled into a module.
Does kbuild really compile pcie-tegra194.c twice? And if so, it's not
a problem that both the static kernel and the module contain a
tegra194_pcie_ops symbol?
> ifdef CONFIG_ACPI
> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> index b19775ab134e..ae70e53a7826 100644
> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> @@ -240,13 +240,16 @@
> #define EP_STATE_DISABLED 0
> #define EP_STATE_ENABLED 1
>
> +#if IS_ENABLED(CONFIG_PCIE_TEGRA194)
> static const unsigned int pcie_gen_freq[] = {
> GEN1_CORE_CLK_FREQ,
> GEN2_CORE_CLK_FREQ,
> GEN3_CORE_CLK_FREQ,
> GEN4_CORE_CLK_FREQ
> };
> +#endif
This makes the minimal patch, but as Krzysztof suggests, I would
prefer to move the whole struct so it's just inside the
CONFIG_PCIE_TEGRA194 #ifdef.
> +#if defined(CONFIG_PCIEASPM)
> static const u32 event_cntr_ctrl_offset[] = {
> 0x1d8,
> 0x1a8,
> @@ -264,6 +267,7 @@ static const u32 event_cntr_data_offset[] = {
> 0x1c8,
> 0x1dc
> };
> +#endif
Similar for the CONFIG_PCIEASPM #ifdef.
> struct tegra_pcie_dw {
> struct device *dev;
> @@ -409,7 +413,7 @@ const struct pci_ecam_ops tegra194_pcie_ops = {
> };
> #endif /* defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS) */
>
> -#ifdef CONFIG_PCIE_TEGRA194
> +#if IS_ENABLED(CONFIG_PCIE_TEGRA194)
> static inline struct tegra_pcie_dw *to_tegra_pcie(struct dw_pcie *pci)
> {
> --
> 2.25.1
>
