| Message ID | be1c35eb997959b4939b304ef26664dfb9cd2275.1621941451.git.esben@geanix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARM: imx: only enable pinctrl as needed | expand |
On Tue, May 25, 2021 at 1:22 PM Esben Haabendal <esben@geanix.com> wrote: > > As not all mach-imx platforms has support for run-time changes of pin > configurations (such as LS1021A), a more selective approach to enabling > pinctrl infrastructure makes sense, so that an e.g. an LS1021A only kernel > could be built without pinctrl support. > > Signed-off-by: Esben Haabendal <esben@geanix.com> I think it would be even better to leave all these drivers to be user-configurable. The symbols are currently defined as e.g. config PINCTRL_IMX51 bool "IMX51 pinctrl driver" depends on SOC_IMX51 select PINCTRL_IMX help Say Y here to enable the imx51 pinctrl driver which could be changed to config PINCTRL_IMX51 bool "IMX51 pinctrl driver" if COMPILE_TEST && !SOC_IMX51 depends on OF default SOC_IMX51 select PINCTRL_IMX help Say Y here to enable the imx51 pinctrl driver Today, having it configurable is pointless because you can't turn it off when SOC_IMX51 is set, and you can't turn it on when SOC_IMX51 is disabled. The second version allows turning off PINCTRL completely though, as we do for other top-level subsystems that would likely make the system unusable when disabled (block, serial, ...), and it allows compile-testing on other machines, provided some dependencies (CONFIG_OF in the example) are met. It could theoretically also allow making it a 'tristate' option, as we do for an increasing number of drivers. Arnd
On Fri, May 28, 2021 at 9:55 AM Arnd Bergmann <arnd@arndb.de> wrote: > I think it would be even better to leave all these drivers to be > user-configurable. The symbols are currently defined as e.g. > > config PINCTRL_IMX51 > bool "IMX51 pinctrl driver" > depends on SOC_IMX51 > select PINCTRL_IMX > help > Say Y here to enable the imx51 pinctrl driver > > which could be changed to > > config PINCTRL_IMX51 > bool "IMX51 pinctrl driver" if COMPILE_TEST && !SOC_IMX51 > depends on OF > default SOC_IMX51 > select PINCTRL_IMX > help > Say Y here to enable the imx51 pinctrl driver > > Today, having it configurable is pointless because you can't turn it off > when SOC_IMX51 is set, and you can't turn it on when SOC_IMX51 > is disabled. I agree this looks better. With pin control drivers I think this often reflects the desire to not make it possible to build a kernel that will not boot. Usually this is because initramfs is assumed not to be used to house the most necessary modules, so any modules need to be loaded later from e.g. eMMC and that of course needs pin control before it can be mounted. I think it is a bit of "embedded culture" to do things like this, because the distro way with modules and initramfs isn't used by all embedded build environments like it is on your regular Debian, Fedora, ... etc. Instead they assume a monolithic kernel tailored for the hardware to a certain extent. Maybe we need to clarify somehow that the driving idea behind multiplatform also assumes modularization and using initramfs for the most necessary modules and things like that. Yours, Linus Walleij
On 28/05/2021 09.53, Arnd Bergmann wrote: > On Tue, May 25, 2021 at 1:22 PM Esben Haabendal <esben@geanix.com> wrote: >> >> As not all mach-imx platforms has support for run-time changes of pin >> configurations (such as LS1021A), a more selective approach to enabling >> pinctrl infrastructure makes sense, so that an e.g. an LS1021A only kernel >> could be built without pinctrl support. >> >> Signed-off-by: Esben Haabendal <esben@geanix.com> > > I think it would be even better to leave all these drivers to be > user-configurable. The symbols are currently defined as e.g. > > config PINCTRL_IMX51 > bool "IMX51 pinctrl driver" > depends on SOC_IMX51 > select PINCTRL_IMX > help > Say Y here to enable the imx51 pinctrl driver > > which could be changed to > > config PINCTRL_IMX51 > bool "IMX51 pinctrl driver" if COMPILE_TEST && !SOC_IMX51 > depends on OF > default SOC_IMX51 > select PINCTRL_IMX > help > Say Y here to enable the imx51 pinctrl driver > > Today, having it configurable is pointless because you can't turn it off > when SOC_IMX51 is set, and you can't turn it on when SOC_IMX51 > is disabled. But if you want to allow turning it off when SOC_IMX51 is set, don't you want this to be config PINCTRL_IMX51 bool "IMX51 pinctrl driver" depends on OF depends on COMPILE_TEST || SOC_IMX51 default SOC_IMX51 select PINCTRL_IMX help Say Y here to enable the imx51 pinctrl driver (otherwise, the !SOC_IMX51 condition on the prompt means it's not a visible and thus changeable item). But I think all the COMPILE_TEST would be better done later; it's not immediately clear what "depends on" one would have to add in lieu of SOC_${soc}. > The second version allows turning off PINCTRL completely though, I'm not really sure what "second version" you're talking about here. If you refer to Esben's original patch, that is indeed the whole goal - getting rid of the pinctrl core code and anything else which is under #ifdef CONFIG_PINCTRL which is useless on ls1021a (and its absence does not make the board unbootable). Rasmus
diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig index b407b024dde3..3fc170456cde 100644 --- a/arch/arm/mach-imx/Kconfig +++ b/arch/arm/mach-imx/Kconfig @@ -6,7 +6,6 @@ menuconfig ARCH_MXC select CLKSRC_IMX_GPT select GENERIC_IRQ_CHIP select GPIOLIB - select PINCTRL select PM_OPP if PM select SOC_BUS select SRAM @@ -61,6 +60,7 @@ config SOC_IMX31 config SOC_IMX35 bool "i.MX35 support" select MXC_AVIC + select PINCTRL select PINCTRL_IMX35 help This enables support for Freescale i.MX35 processor @@ -73,6 +73,7 @@ config SOC_IMX1 bool "i.MX1 support" select CPU_ARM920T select MXC_AVIC + select PINCTRL select PINCTRL_IMX1 help This enables support for Freescale i.MX1 processor @@ -85,6 +86,7 @@ config SOC_IMX25 bool "i.MX25 support" select CPU_ARM926T select MXC_AVIC + select PINCTRL select PINCTRL_IMX25 help This enables support for Freescale i.MX25 processor @@ -93,6 +95,7 @@ config SOC_IMX27 bool "i.MX27 support" select CPU_ARM926T select MXC_AVIC + select PINCTRL select PINCTRL_IMX27 help This enables support for Freescale i.MX27 processor @@ -110,6 +113,7 @@ config SOC_IMX5 config SOC_IMX50 bool "i.MX50 support" + select PINCTRL select PINCTRL_IMX50 select SOC_IMX5 @@ -118,6 +122,7 @@ config SOC_IMX50 config SOC_IMX51 bool "i.MX51 support" + select PINCTRL select PINCTRL_IMX51 select SOC_IMX5 help @@ -125,6 +130,7 @@ config SOC_IMX51 config SOC_IMX53 bool "i.MX53 support" + select PINCTRL select PINCTRL_IMX53 select SOC_IMX5 @@ -149,6 +155,7 @@ config SOC_IMX6Q select ARM_ERRATA_775420 select HAVE_ARM_SCU if SMP select HAVE_ARM_TWD + select PINCTRL select PINCTRL_IMX6Q select SOC_IMX6 @@ -159,6 +166,7 @@ config SOC_IMX6SL bool "i.MX6 SoloLite support" select ARM_ERRATA_754322 select ARM_ERRATA_775420 + select PINCTRL select PINCTRL_IMX6SL select SOC_IMX6 @@ -169,6 +177,7 @@ config SOC_IMX6SLL bool "i.MX6 SoloLiteLite support" select ARM_ERRATA_754322 select ARM_ERRATA_775420 + select PINCTRL select PINCTRL_IMX6SLL select SOC_IMX6 @@ -179,6 +188,7 @@ config SOC_IMX6SX bool "i.MX6 SoloX support" select ARM_ERRATA_754322 select ARM_ERRATA_775420 + select PINCTRL select PINCTRL_IMX6SX select SOC_IMX6 @@ -187,6 +197,7 @@ config SOC_IMX6SX config SOC_IMX6UL bool "i.MX6 UltraLite support" + select PINCTRL select PINCTRL_IMX6UL select SOC_IMX6 select ARM_ERRATA_814220 @@ -223,6 +234,7 @@ config SOC_IMX7D_CM4 config SOC_IMX7D bool "i.MX7 Dual support" + select PINCTRL select PINCTRL_IMX7D select SOC_IMX7D_CA7 if ARCH_MULTI_V7 select SOC_IMX7D_CM4 if ARM_SINGLE_ARMV7M @@ -233,6 +245,7 @@ config SOC_IMX7D config SOC_IMX7ULP bool "i.MX7ULP support" select CLKSRC_IMX_TPM + select PINCTRL select PINCTRL_IMX7ULP select SOC_IMX7D_CA7 if ARCH_MULTI_V7 select SOC_IMX7D_CM4 if ARM_SINGLE_ARMV7M @@ -242,6 +255,7 @@ config SOC_IMX7ULP config SOC_VF610 bool "Vybrid Family VF610 support" select ARM_GIC if ARCH_MULTI_V7 + select PINCTRL select PINCTRL_VF610 help
As not all mach-imx platforms has support for run-time changes of pin configurations (such as LS1021A), a more selective approach to enabling pinctrl infrastructure makes sense, so that an e.g. an LS1021A only kernel could be built without pinctrl support. Signed-off-by: Esben Haabendal <esben@geanix.com> --- arch/arm/mach-imx/Kconfig | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)