On Mon, 2026-11-02 at 10:42 -0600, David Lechner wrote:
> On 10/30/26 3:57 AM, Steffen Dirkwinkel wrote:
> > From: Steffen Dirkwinkel <[email protected]>
> >
> > Device tree walks and other setup is very slow without caches, so turn
> > them on before relocation.
> >
> > On an MT8370 module, from bootstage marks before each initcall, two
> > boots each:
> >
> > step caches off caches on
> > initf_dm 349.8 / 349.7 4.6 / 4.6 ms
> > serial_init 204.7 / 204.7 3.0 / 3.0 ms
> > dram_init 162.2 / 162.1 2.3 / 2.3 ms
> > relocate_code 22.0 / 22.0 0.4 / 0.4 ms
> > board_init_f() to main_loop() 819 / 819 87 / 87 ms
> >
> > and from the serial console, after power-on (includes 5s debug usb wait):
> >
> > U-Boot banner 7346 / 7346 ms 6772 / 6777 / 6765 ms
> >
> > Signed-off-by: Steffen Dirkwinkel <[email protected]>
> > ---
> > arch/arm/mach-mediatek/cpu.c | 14 ++++++++++++++
> > arch/arm/mach-mediatek/mt8188/init.c | 23 ++++++++++++++++++++---
> > 2 files changed, 34 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/arm/mach-mediatek/cpu.c b/arch/arm/mach-mediatek/cpu.c
> > index 04ede8823b07..484a50f0a25c 100644
> > --- a/arch/arm/mach-mediatek/cpu.c
> > +++ b/arch/arm/mach-mediatek/cpu.c
> > @@ -7,10 +7,13 @@
> > #include <dm.h>
> > #include <init.h>
> > #include <wdt.h>
> > +#include <asm/global_data.h>
> > #include <dm/uclass-internal.h>
> > #include <linux/arm-smccc.h>
> > #include <linux/types.h>
> >
> > +DECLARE_GLOBAL_DATA_PTR;
> > +
> > #define MTK_SIP_PLAT_BINFO ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,
> > ARM_SMCCC_SMC_64, \
> > ARM_SMCCC_OWNER_SIP, 0x529)
> >
> > @@ -23,6 +26,17 @@ int arch_cpu_init(void)
> >
> > void enable_caches(void)
> > {
> > +#if IS_ENABLED(CONFIG_TARGET_MT8188) && !IS_ENABLED(CONFIG_XPL_BUILD) && \
> > + !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
>
> instead of checking CONFIG_TARGET_MT8188, this would become the same config
> option I suggested in the previous patch so that we don't have to keep adding
> additional targets.
>
> And U-boot preferred style is to use if statement instead of #if preprocessor
> for things like this. The the compiler will still optimize it out the same.
I didn't do a generic implementation before, because I can only test on mt8188.
But it would be cleaner than doing the same thing for all SOCs and there is
still the DCACHE_OFF kconfigs to enable/disable it, so I'll make it generic in
v2.
>
> > + /* Deactivate the data cache, enabled before relocation in
> > mach_cpu_init() */
> > + dcache_disable();
> > + /*
> > + * Force the call of setup_all_pgtables() in mmu_setup() by clearing
> > + * tlb_fillptr, to use the page tables reserved by arch_reserve_mmu()
> > + */
> > + gd->arch.tlb_fillptr = 0;
> > +#endif
> > +
> > /* Enable D-cache. I-cache is already enabled in start.S */
> > dcache_enable();
> > }
> > diff --git a/arch/arm/mach-mediatek/mt8188/init.c
> > b/arch/arm/mach-mediatek/mt8188/init.c
> > index 2e6aa041c38f..139412071131 100644
> > --- a/arch/arm/mach-mediatek/mt8188/init.c
> > +++ b/arch/arm/mach-mediatek/mt8188/init.c
>
> And similarly, we should try to avoid this target-specific boilerplate that
> would have to be repeated for every target.
>
> > @@ -49,15 +49,32 @@ int print_cpuinfo(void)
> > return 0;
> > }
> >
> > -#if IS_ENABLED(CONFIG_XPL_BUILD) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
> > +#if !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
> > /* Early page tables, in DRAM unused by SPL and by U-Boot before
> > relocation */
> > #define MT8188_EARLY_TLB_ADDR 0x4e000000
> >
> > -/* Initialize the MMU and activate the data cache in SPL */
> > -void mtk_spl_enable_caches(void)
> > +/*
> > + * Initialize the MMU and activate the data cache in SPL and in the U-Boot
> > + * pre-reloc stage. The MMU/TLB is updated in enable_caches() after
> > relocation.
> > + */
> > +static void mt8188_enable_early_caches(void)
> > {
> > gd->arch.tlb_addr = MT8188_EARLY_TLB_ADDR;
> > gd->arch.tlb_size = PGTABLE_SIZE;
> > dcache_enable();
> > }
> > +
> > +#if IS_ENABLED(CONFIG_XPL_BUILD)
> > +void mtk_spl_enable_caches(void)
> > +{
> > + mt8188_enable_early_caches();
> > +}
> > +#else
> > +int mach_cpu_init(void)
> > +{
> > + mt8188_enable_early_caches();
> > +
> > + return 0;
> > +}
> > +#endif
> > #endif
> >
