Re: [PATCH 1/4] of/fdt: Update zone_dma_bits when running in bcm2711

Catalin Marinas
2020-10-01T17:23:29Z

On Thu, Oct 01, 2020 at 06:15:01PM +0100, Catalin Marinas wrote:
> 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.

Actually, even better, could we not move the check to
arm64_memblock_init() when we initialise zone_dma_bits?

--
Catalin