On Wed, 3 Jun 2026 at 17:18, Marek Vasut <[email protected]> wrote: > > Some architectures can not DMA above 4 GiB boundary, > limit available memory to memory below 4 GiB boundary. > > Signed-off-by: Marek Vasut <[email protected]> > --- > Cc: Andrew Goodbody <[email protected]> > Cc: David Lechner <[email protected]> > Cc: Heiko Schocher <[email protected]> > Cc: Heinrich Schuchardt <[email protected]> > Cc: Holger Brunck <[email protected]> > Cc: Ilias Apalodimas <[email protected]> > Cc: Peter Robinson <[email protected]> > Cc: Quentin Schulz <[email protected]> > Cc: Simon Glass <[email protected]> > Cc: Sughosh Ganu <[email protected]> > Cc: Tom Rini <[email protected]> > Cc: [email protected] > --- > V1: Invert the IS_ENABLED(CONFIG_LMB_LIMIT_DMA_BELOW_4G) conditional > ---
Reviewed-by: Ilias Apalodimas <[email protected]> Tested-by: Ilias Apalodimas <[email protected]> #rpi4 8GiB > lib/Kconfig | 8 ++++++++ > lib/lmb.c | 20 +++++++++++++++++++- > 2 files changed, 27 insertions(+), 1 deletion(-) > > diff --git a/lib/Kconfig b/lib/Kconfig > index 77ebc79e1db..29911068a69 100644 > --- a/lib/Kconfig > +++ b/lib/Kconfig > @@ -1295,6 +1295,14 @@ config SPL_LMB_ARCH_MEM_MAP > memory map. Enable this config in such scenarios which allow > architectures and boards to define their own memory map. > > +config LMB_LIMIT_DMA_BELOW_4G > + bool > + depends on LMB > + default y if ARCH_BCM283X > + help > + Some architectures can not DMA above 4 GiB boundary, > + limit available memory to memory below 4 GiB boundary. > + > config PHANDLE_CHECK_SEQ > bool "Enable phandle check while getting sequence number" > help > diff --git a/lib/lmb.c b/lib/lmb.c > index 8f12c6ad8e5..a2aeb526e29 100644 > --- a/lib/lmb.c > +++ b/lib/lmb.c > @@ -611,6 +611,7 @@ static __maybe_unused void lmb_reserve_common_spl(void) > static void lmb_add_memory(void) > { > int i; > + phys_addr_t bank_end; > phys_size_t size; > u64 ram_top = gd->ram_top; > struct bd_info *bd = gd->bd; > @@ -625,8 +626,25 @@ static void lmb_add_memory(void) > for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) { > size = bd->bi_dram[i].size; > > - if (size) > + if (size) { > lmb_add(bd->bi_dram[i].start, size); > + if (!IS_ENABLED(CONFIG_LMB_LIMIT_DMA_BELOW_4G)) > + continue; > + > + bank_end = bd->bi_dram[i].start + size; > + > + /* > + * Reserve memory above ram_top as > + * no-overwrite so that it cannot be > + * allocated > + */ > + if (bd->bi_dram[i].start >= ram_top) > + lmb_reserve(bd->bi_dram[i].start, size, > + LMB_NOOVERWRITE); > + else if (bank_end > ram_top) > + lmb_reserve(ram_top, bank_end - ram_top, > + LMB_NOOVERWRITE); > + } > } > } > > -- > 2.53.0 >
