Hi Nicolas, Thanks for putting this together. On Thu, Oct 01, 2020 at 06:17:37PM +0200, Nicolas Saenz Julienne wrote: > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index 4602e467ca8b..cd0d115ef329 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -25,6 +25,7 @@ > #include <linux/serial_core.h> > #include <linux/sysfs.h> > #include <linux/random.h> > +#include <linux/dma-direct.h> /* for zone_dma_bits */ > > #include <asm/setup.h> /* for COMMAND_LINE_SIZE */ > #include <asm/page.h> > @@ -1198,6 +1199,14 @@ void __init early_init_dt_scan_nodes(void) > of_scan_flat_dt(early_init_dt_scan_memory, NULL); > } > > +void __init early_init_dt_update_zone_dma_bits(void) > +{ > + unsigned long dt_root = of_get_flat_dt_root(); > + > + if (of_flat_dt_is_compatible(dt_root, "brcm,bcm2711")) > + zone_dma_bits = 30; > +} I think we could keep this entirely in the arm64 setup_machine_fdt() and not pollute the core code with RPi4-specific code. -- Catalin