linux-kernel - Re: [PATCH] powerpc/prom_init: Fixup missing powermac #size-cells

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Message-ID: <CAL_JsqKJzAoxFQ30rJbH7D7zmGtZ+jNpw2BL45dqjOUe2fFbwA@mail.gmail.com>
Date: Tue, 26 Nov 2024 07:37:17 -0600
From: Rob Herring <robh@...nel.org>
To: Michael Ellerman <mpe@...erman.id.au>
Cc: linuxppc-dev@...ts.ozlabs.org, saravanak@...gle.com, 
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH] powerpc/prom_init: Fixup missing powermac #size-cells

On Mon, Nov 25, 2024 at 8:57 PM Michael Ellerman <mpe@...erman.id.au> wrote:
>
> On some powermacs `escc` nodes are missing `#size-cells` properties,
> which is deprecated and now triggers a warning at boot since commit
> 045b14ca5c36 ("of: WARN on deprecated #address-cells/#size-cells
> handling").
>
> For example:
>
>   Missing '#size-cells' in /pci@...00000/mac-io@...scc@...00
>   WARNING: CPU: 0 PID: 0 at drivers/of/base.c:133 of_bus_n_size_cells+0x98/0x108
>   Hardware name: PowerMac3,1 7400 0xc0209 PowerMac
>   ...
>   Call Trace:
>     of_bus_n_size_cells+0x98/0x108 (unreliable)
>     of_bus_default_count_cells+0x40/0x60
>     __of_get_address+0xc8/0x21c
>     __of_address_to_resource+0x5c/0x228
>     pmz_init_port+0x5c/0x2ec
>     pmz_probe.isra.0+0x144/0x1e4
>     pmz_console_init+0x10/0x48
>     console_init+0xcc/0x138
>     start_kernel+0x5c4/0x694
>
> As powermacs boot via prom_init it's possible to add the missing
> properties to the device tree during boot, avoiding the warning. Note
> that `escc-legacy` nodes are also missing `#size-cells` properties, but
> they are skipped by the macio driver, so leave them alone.
>
> Depends-on: 045b14ca5c36 ("of: WARN on deprecated #address-cells/#size-cells handling")
> Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
> ---
>  arch/powerpc/kernel/prom_init.c | 29 +++++++++++++++++++++++++++--
>  1 file changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
> index 73210e5bcfa7..8e776ba39497 100644
> --- a/arch/powerpc/kernel/prom_init.c
> +++ b/arch/powerpc/kernel/prom_init.c
> @@ -2848,7 +2848,7 @@ static void __init fixup_device_tree_chrp(void)
>  #endif
>
>  #if defined(CONFIG_PPC64) && defined(CONFIG_PPC_PMAC)
> -static void __init fixup_device_tree_pmac(void)
> +static void __init fixup_device_tree_pmac64(void)
>  {
>         phandle u3, i2c, mpic;
>         u32 u3_rev;
> @@ -2888,7 +2888,31 @@ static void __init fixup_device_tree_pmac(void)
>                      &parent, sizeof(parent));
>  }
>  #else
> -#define fixup_device_tree_pmac()
> +#define fixup_device_tree_pmac64()
> +#endif
> +
> +#ifdef CONFIG_PPC_PMAC
> +static void __init fixup_device_tree_pmac(void)
> +{
> +       __be32 val = 1;
> +       char type[8];
> +       phandle node;

I suppose you are keeping the existing style, but you could use
IS_ENABLED() here instead of #ifdef.

Either way,

Reviewed-by: Rob Herring <robh@...nel.org>