linux-kernel - Re: [PATCH v3 2/3] arm: shmobile: Add the R9A06G032 SMP enabler driver

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Date:   Fri, 25 May 2018 11:49:13 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Michel Pollet <michel.pollet@...renesas.com>
Cc:     Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Simon Horman <horms@...ge.net.au>,
        Michel Pollet <buserror+upstream@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Juri Lelli <juri.lelli@....com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Magnus Damm <magnus.damm@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Chen-Yu Tsai <wens@...e.org>, Rob Herring <robh+dt@...nel.org>,
        Carlo Caione <carlo@...lessm.com>,
        Kevin Hilman <khilman@...libre.com>,
        Andreas Färber <afaerber@...e.de>,
        Frank Rowand <frank.rowand@...y.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 2/3] arm: shmobile: Add the R9A06G032 SMP enabler driver

Hi Michel,

On Thu, May 24, 2018 at 12:30 PM, Michel Pollet
<michel.pollet@...renesas.com> wrote:
> The Renesas R9A06G032 second CA7 is parked in a ROM pen at boot time, it
> requires a special enable method to get it started.
>
> Signed-off-by: Michel Pollet <michel.pollet@...renesas.com>

Thanks for your patch!

>  arch/arm/mach-shmobile/smp-r9a06g032.c | 85 ++++++++++++++++++++++++++++++++++

I think you can safely call this driver smp-rzn1d.c, or smp-rzn1.c.
Source files are not covered by the stable DT ABI, and can be reordered
later at will.

I expect you will just add more CPU_METHOD_OF_DECLARE() lines later
(perhaps with a little bit of extra code to handle deviations).

> --- /dev/null
> +++ b/arch/arm/mach-shmobile/smp-r9a06g032.c
> @@ -0,0 +1,85 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * RZ/N1D Second CA7 enabler.
> + *
> + * Copyright (C) 2018 Renesas Electronics Europe Limited
> + *
> + * Michel Pollet <michel.pollet@...renesas.com>, <buserror@...il.com>
> + * Derived from action,s500-smp
> + */
> +
> +#include <linux/delay.h>

Do you need this?

> +#include <asm/cacheflush.h>
> +#include <asm/smp_plat.h>
> +#include <asm/smp_scu.h>

Do you need these?

> +static void __init rzn1_smp_prepare_cpus(unsigned int max_cpus)
> +{
> +       struct device_node *dn;
> +       int ret;
> +       u32 bootaddr;

> +       pr_info("CPU#1: cpu-release-addr %08x\n", (u32)bootaddr);

The cast is not needed.

> +
> +       cpu_bootaddr = ioremap(bootaddr, sizeof(bootaddr));
> +       if (!cpu_bootaddr)
> +               pr_err("CPU#1: cpu-release-addr map failed\n");

If this fails, that is basically an OOM condition, which will scream anyway.
So I think you should drop the error message.

> +}

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds