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

Nicolas Saenz Julienne
2020-10-01T17:31:28Z

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On Thu, 2020-10-01 at 18:23 +0100, Catalin Marinas wrote:
> 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?

I did it this way as I vaguely remembered Rob saying he wanted to centralise
all early boot fdt code in one place. But I'll be happy to move it there.

Regards,
Nicolas

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