linux-kernel - Re: [PATCH] riscv: Do not invoke early_init_dt_verify() twice

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Message-ID: <20210325155550.udz33f3kivbi7j76@mail.google.com>
Date:   Thu, 25 Mar 2021 15:55:51 +0000
From:   Changbin Du <changbin.du@...il.com>
To:     Anup Patel <anup@...infault.org>
Cc:     Changbin Du <changbin.du@...il.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] riscv: Do not invoke early_init_dt_verify() twice

On Wed, Mar 24, 2021 at 08:51:06PM +0530, Anup Patel wrote:
> On Wed, Mar 24, 2021 at 8:33 PM Changbin Du <changbin.du@...il.com> wrote:
> >
> > In the setup_arch() of riscv, function early_init_dt_verify() has
> > been done by parse_dtb(). So no need to call it again. Just directly
> > invoke unflatten_device_tree().
> >
> > Signed-off-by: Changbin Du <changbin.du@...il.com>
> > ---
> >  arch/riscv/kernel/setup.c | 5 +----
> >  1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> > index f8f15332caa2..2a3d487e1710 100644
> > --- a/arch/riscv/kernel/setup.c
> > +++ b/arch/riscv/kernel/setup.c
> > @@ -255,10 +255,7 @@ void __init setup_arch(char **cmdline_p)
> >  #if IS_ENABLED(CONFIG_BUILTIN_DTB)
> >         unflatten_and_copy_device_tree();
> >  #else
> > -       if (early_init_dt_verify(__va(dtb_early_pa)))
> > -               unflatten_device_tree();
> > -       else
> > -               pr_err("No DTB found in kernel mappings\n");
> > +       unflatten_device_tree();
> >  #endif
> 
> The early_init_dt_verify() set he DTB base address in Linux OF.
> 
> When parse_dtb() calls early_init_dt_verify(), MMU is enabled but
> we have temporary mapping for DTB (i.e. dtb_early_va).
> 
> After paging_init(), we have moved to final swapper_pg_dir so
> temporary mapping for DTB does not exists anymore but DTB
> is at same physical address so update DTB base address in
> Linux OF by calling early_init_dt_verify() again.
> 
> Based on above, NACK to this patch.
>
No problem, thanks!
 
> Regards,
> Anup
> 
> >         misc_mem_init();
> >
> > --
> > 2.30.2
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv

-- 
Cheers,
Changbin Du

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