Re: [PATCH v2 06/10] mach-snapdragon: Kconfig: changes / additions to support SPL

[Tom Rini <trini@konsulko.com>]

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On Sat, Apr 18, 2026 at 03:01:22AM +0200, Michael Srba wrote:
> Hi,
> 
> On 4/13/26 19:17, Tom Rini wrote:
> > On Sat, Apr 11, 2026 at 02:00:11AM +0200, michael.srba@seznam.cz wrote:
> > 
> > > From: Michael Srba <Michael.Srba@seznam.cz>
> > > 
> > > An SoC to target has to be selected, e.g. SPL_TARGET_SDM845.
> > > This will select reasonable defaults and enable per-SoC linker
> > > script (if required).
> > > 
> > > Signed-off-by: Michael Srba <Michael.Srba@seznam.cz>
> > > ---
> > >   arch/arm/Kconfig                 | 31 +++++++++++++++++++++++++++-
> > >   arch/arm/mach-snapdragon/Kconfig | 44 ++++++++++++++++++++++++++++++++++------
> > >   2 files changed, 68 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> > > index 03416c55265..8490e336516 100644
> > > --- a/arch/arm/Kconfig
> > > +++ b/arch/arm/Kconfig
> > > @@ -1138,9 +1138,38 @@ config ARCH_SNAPDRAGON
> > >   	select SAVE_PREV_BL_FDT_ADDR if !ENABLE_ARM_SOC_BOOT0_HOOK
> > >   	select LINUX_KERNEL_IMAGE_HEADER if !ENABLE_ARM_SOC_BOOT0_HOOK
> > >   	select SYSRESET
> > > -	select SYSRESET_PSCI
> > > +	select SYSRESET_PSCI if !SPL
> > >   	select ANDROID_BOOT_IMAGE_IGNORE_BLOB_ADDR
> > >   	select MMU_PGPROT
> > > +	select SUPPORT_SPL
> > > +	select ARMV8_SPL_EXCEPTION_VECTORS if SPL
> > > +	select ENABLE_ARM_SOC_BOOT0_HOOK if SPL
> > > +	select SPL_DM if SPL
> > > +	select SPL_DM_GPIO if SPL
> > > +	select SPL_DM_PMIC if SPL
> > > +	select SPL_DM_USB_GADGET if SPL
> > > +	select SPL_ENV_SUPPORT if SPL
> > > +	select SPL_GPIO if SPL
> > > +	select SPL_HAS_BSS_LINKER_SECTION if SPL
> > > +	select SPL_LIBCOMMON_SUPPORT if SPL
> > > +	select SPL_LIBDISK_SUPPORT if SPL
> > > +	select SPL_LIBGENERIC_SUPPORT if SPL
> > > +	select SPL_MMC if SPL
> > > +	select SPL_OF_REAL if SPL
> > > +	select SPL_OF_CONTROL if SPL
> > > +	select SPL_PINCONF if SPL
> > > +	select SPL_PINCTRL if SPL
> > > +	select SPL_PINCTRL_FULL if SPL
> > > +	select SPL_PINCTRL_GENERIC if SPL
> > > +	select SPL_PINCONF_RECURSIVE if SPL
> > > +	select SPL_PINMUX if SPL
> > > +	select SPL_SPRINTF if SPL
> > > +	select SPL_STRTO if SPL
> > > +	select SPL_USB_GADGET if SPL
> > > +	imply DM_EVENT if USB_DWC3_GENERIC || SPL_USB_DWC3_GENERIC
> > > +	imply SPL_EVENT if SPL_USB_DWC3_GENERIC
> > > +	imply OF_LIVE if USB_DWC3_GENERIC
> > > +	imply SPL_OF_LIVE if SPL_USB_DWC3_GENERIC
> > >   	imply OF_UPSTREAM
> > >   	imply CMD_DM
> > >   	imply DM_USB_GADGET
> > This part looks good.
> > 
> > > diff --git a/arch/arm/mach-snapdragon/Kconfig b/arch/arm/mach-snapdragon/Kconfig
> > > index 976c0e35fce..74d687ceee2 100644
> > > --- a/arch/arm/mach-snapdragon/Kconfig
> > > +++ b/arch/arm/mach-snapdragon/Kconfig
> > > @@ -11,18 +11,12 @@ config SYS_VENDOR
> > >   	  Based on this option board/<CONFIG_SYS_VENDOR>/<CONFIG_SYS_BOARD>
> > >   	  will be used as the custom board directory.
> > > -config SYS_MALLOC_LEN
> > > -	default 0x10000000
> > > -
> > >   config SYS_MALLOC_F_LEN
> > >   	default 0x2000
> > >   config SPL_SYS_MALLOC_F
> > >   	default y
> > > -config SPL_SYS_MALLOC_F_LEN
> > > -	default 0x2000
> > > -
> > >   config SYS_MALLOC_LEN
> > >   	default 0x800000
> > > @@ -45,4 +39,42 @@ config SYS_CONFIG_NAME
> > >   	  Based on this option include/configs/<CONFIG_SYS_CONFIG_NAME>.h header
> > >   	  will be used for board configuration.
> > > +config SPL_SHARES_INIT_SP_ADDR
> > > +	default n
> > > +
> > > +config SPL_HAVE_INIT_STACK
> > > +	default y
> > > +
> > > +# SPL targets
> > > +
> > > +config SPL_TARGET_SDM845
> > > +	bool "Set reasonable default values for running SPL in SRAM on sdm845 devices"
> > This namespace is confusing and so shouldn't be used. Does SDM845 get
> > used without SPL? We should probably follow the convention of adding a
> > new defconfig of <whatever board>_spl_defconfig, that enables the
> > options as needed.
> The rationale for this naming was that outside SPL, we don't currently
> discriminate between SoCs at compile time (there is some discrimination
> between legacy board support the and unified "board" which covers all
> non-legacy boards no matter the SoC, but for non-legacy boards there
> is just a single build of U-Boot proper, possibly with a board dtb
> appended if used as the primary bootloader). I suppose the SPL_ prefix
> may be confusing and isn't strictly necessary, and we may need a similar
> target option for msm8916 in the future which wouldn't be used in SPL
> but in u-boot proper, so it makes sense to get rid of the prefix.
> 
> The reason we need this config option at all (even if we move all
> the Kconfig defaults that use it into the defconfig) is that the
> boot0.h is shared among all of mach-snapdragon, and we need a way
> to select which SoC-specific boot0.h we should include.
> Now, it does look like SYS_SOC is intended for stuff like this,
> however changing SYS_SOC from snapdragon seems to completely break
> the unified board support which isn't really worth it.
> 
> Admittedly, it does seem that I somehow completely forgot to mention that
> use of the config option in both the commit message and the Kconfig,
> but it is effectively the only use it has left after moving everything
> into the defconfig.
> 
> So, should I include an SoC selection menu similar to the board selection
> menus in e.g mach-exynos, which would now solely be used by the ifdef
> in boot0.h? Something like
> ```
> choice
>     prompt "Qualcomm SoC select"
>     default TARGET_NONE if !SPL
>     help
>       While U-Boot on Qualcomm platforms doesn't generally need compile-time
>       adjustment based on the target SoC, there are a few exceptions to this.
>       Currently this concerns boot0.h discrimination.
> 
> config TARGET_NONE
>     bool "Generic build"
>     help
>       Select this if you're not building SPL. U-Boot proper builds are currently
>       generic across all SoCs.
> 
> config TARGET_SDM845
>     bool "SPL targeting the sdm845 SoC"
>     help
>       Select this if you are bulding u-boot SPL for sdm845.
>       Currently this gates sdm845-specific boot0.h (only used in SPL).
> 
> endchoice
> ```
> 
> ... or do you have something else in mind? I'm not entirely sure if you're
> suggesting to get rid of TARGET_SDM845 completely (which I really don't see
> as possible at least without a lot of unnecessary pain) or just of it's
> use for the defaults.

That's for explaining more. The SPL_xxx namespace is generally reserved
so that we can do things like:
obj-$(CONFIG_$(PHASE)FOO) += foo.o
in a Makefile, and have symbols for SPL_FOO, FOO (and TPL_FOO).

So I think your suggestion here is fine, pending feedback from the
snapdragon maintainers.

-- 
Tom

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