linux-kernel - Re: [PATCH v5 08/13] ARM: sunxi: Add initialization of CNTVOFF

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Message-ID: <20180403220628.19c9acaf@dell-desktop.home>
Date:   Tue, 3 Apr 2018 22:06:28 +0200
From:   Mylène Josserand <mylene.josserand@...tlin.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     linux@...linux.org.uk, wens@...e.org, marc.zyngier@....com,
        mark.rutland@....com, robh+dt@...nel.org,
        devicetree@...r.kernel.org, clabbe.montjoie@...il.com,
        quentin.schulz@...tlin.com, thomas.petazzoni@...tlin.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 08/13] ARM: sunxi: Add initialization of CNTVOFF

Hello,

Thank you for the review.

On Tue, 3 Apr 2018 11:12:18 +0200
Maxime Ripard <maxime.ripard@...tlin.com> wrote:

> On Tue, Apr 03, 2018 at 08:18:31AM +0200, Mylène Josserand wrote:
> > Add the initialization of CNTVOFF for sun8i-a83t.
> > 
> > For boot CPU, Create a new machine that handles this
> > function's call in an "init_early" callback.
> > For secondary CPUs, add this function into secondary_startup
> > assembly entry.
> > 
> > Signed-off-by: Mylène Josserand <mylene.josserand@...tlin.com>
> > ---
> >  arch/arm/mach-sunxi/headsmp.S |  1 +
> >  arch/arm/mach-sunxi/sunxi.c   | 18 +++++++++++++++++-
> >  2 files changed, 18 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm/mach-sunxi/headsmp.S b/arch/arm/mach-sunxi/headsmp.S
> > index 79890fbe5613..b586b7cf803a 100644
> > --- a/arch/arm/mach-sunxi/headsmp.S
> > +++ b/arch/arm/mach-sunxi/headsmp.S
> > @@ -71,6 +71,7 @@ ENDPROC(sunxi_mc_smp_cluster_cache_enable)
> >  
> >  ENTRY(sunxi_mc_smp_secondary_startup)
> >  	bl	sunxi_mc_smp_cluster_cache_enable
> > +	bl	smp_init_cntvoff
> >  	b	secondary_startup
> >  ENDPROC(sunxi_mc_smp_secondary_startup)
> >  
> > diff --git a/arch/arm/mach-sunxi/sunxi.c b/arch/arm/mach-sunxi/sunxi.c
> > index 5e9602ce1573..090784108c0a 100644
> > --- a/arch/arm/mach-sunxi/sunxi.c
> > +++ b/arch/arm/mach-sunxi/sunxi.c
> > @@ -16,6 +16,7 @@
> >  #include <linux/platform_device.h>
> >  
> >  #include <asm/mach/arch.h>
> > +#include <asm/smp_cntvoff.h>
> >  
> >  static const char * const sunxi_board_dt_compat[] = {
> >  	"allwinner,sun4i-a10",
> > @@ -62,7 +63,6 @@ MACHINE_END
> >  static const char * const sun8i_board_dt_compat[] = {
> >  	"allwinner,sun8i-a23",
> >  	"allwinner,sun8i-a33",
> > -	"allwinner,sun8i-a83t",
> >  	"allwinner,sun8i-h2-plus",
> >  	"allwinner,sun8i-h3",
> >  	"allwinner,sun8i-r40",
> > @@ -75,6 +75,22 @@ DT_MACHINE_START(SUN8I_DT, "Allwinner sun8i Family")
> >  	.dt_compat	= sun8i_board_dt_compat,
> >  MACHINE_END
> >  
> > +void __init sun8i_cntvoff_init(void)
> > +{
> > +	smp_init_cntvoff();  
> 
> Can't this be moved to the SMP setup code?

I tried to put it in the first lines of "sunxi_mc_smp_init" function
but it did not work. I tried to find some callbacks to have an
early "init" and I only found the "init_early"'s one. There is probably
another way to handle that so do not hesitate to tell me any ideas.

> 
> > +}
> > +
> > +static const char * const sun8i_cntvoff_board_dt_compat[] = {
> > +	"allwinner,sun8i-a83t",
> > +	NULL,
> > +};
> > +
> > +DT_MACHINE_START(SUN8I_CNTVOFF_DT, "Allwinner sun8i boards needing cntvoff")  
> 
> All of the SoCs need CNTVOFF, so that doesn't really make sense. Why
> not just calling it for what it is: an A83t?

Sure, I will update it.

Best regards,

-- 
Mylène Josserand, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com