[PATCH v5 3/4] mach-k3: add dynamic mmu fixups for SPL stage

[Ilias Apalodimas]

On Thu, 14 Aug 2025 at 17:52, Anshul Dalal <anshuld at ti.com> wrote:
>
> Hello Ilias,
>
> On Tue Jul 8, 2025 at 1:39 AM IST, Ilias Apalodimas wrote:
> > Hi Anshul,
> >
> > On Thu Jul 3, 2025 at 4:35 PM EEST, Anshul Dalal wrote:
> >> On platforms with spl splash support such as 62p and 62x
> >> (CONFIG_VIDEO=y), the top of DDR is reserved for the framebuffer.
> >>
> >> The size of the framebuffer is computed at runtime by video_reserve.
> >> During the MMU configuration an entry corresponding to the framebuffer
> >> should be dynamically created to properly allocate the required space
> >> for the framebuffer.
> >>
> >> Therefore this patch adds k3_spl_mem_map_init which adds the required
> >> MMU entry by querying the gd after the framebuffer size has been
> >> computed in spl_reserve_video_from_ram_top.
> >>
> >> Signed-off-by: Anshul Dalal <anshuld at ti.com>
> >> ---
> >>  arch/arm/mach-k3/arm64/arm64-mmu.c | 13 ++++++++++++-
> >>  arch/arm/mach-k3/common.c          | 17 ++++++++++++++---
> >>  2 files changed, 26 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/arch/arm/mach-k3/arm64/arm64-mmu.c b/arch/arm/mach-k3/arm64/arm64-mmu.c
> >> index 49dd6fcb23b..b1b287f2114 100644
> >> --- a/arch/arm/mach-k3/arm64/arm64-mmu.c
> >> +++ b/arch/arm/mach-k3/arm64/arm64-mmu.c
> >> @@ -131,6 +131,13 @@ static int k3_setup_extra_mem_banks(unsigned int *map_idx)
> >>      return 0;
> >>  }
> >>
> >> +static void k3_spl_mem_map_init(unsigned int *map_idx)
> >> +{
> >> +    if (CONFIG_IS_ENABLED(VIDEO))
> >> +            k3_mmu_add_cachable_entry(gd_video_bottom(), gd_video_top(),
> >> +                                      map_idx);
> >> +}
> >> +
> >
> > I don't know wnough details for this board, but generally speaking we should be doing
> > this commonly for all arm64 platforms. There's mmu code for that. Can you explain why
> > this is only useful to k3?
> >
>
> Could you point me to the relevant mmu code for it, from what I know
> U-Boot doesn't map the framebuffer region at SPL stage by itself. Though
> I'll replace k3_mmu_add_cachable_entry with something like
> mmu_map_region in the next revision.

We have functions like mmu_set_region_dcache_behaviour(),
mmu_map_region(), mmu_change_region_attr() etc. If you are missing
some configuration for the MMU, we are better off adding it for all
Arm platforms, not k3 specifically.

Thanks
/Ilias
>
> Regards,
> Anshul