Re: [PATCH] ARM: owl: smp: Drop owl_secondary_boot()

From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
To: "Andreas Färber" <afaerber@suse.de>
Cc: "Florian Fainelli" <f.fainelli@gmail.com>,
	linux-arm-kernel@lists.infradead.org, support@lemaker.org,
	张天益 <tyzhang@actions-semi.com>, "Arnd Bergmann" <arnd@arndb.de>,
	梅利 <harrymei@actions-semi.com>,
	linux-kernel@vger.kernel.org,
	"Thomas Liau" <thomas.liau@actions-semi.com>,
	"Russell King" <linux@armlinux.org.uk>,
	support@cubietech.com, lee@cubietech.com,
	张东风 <zhangdf@actions-semi.com>, 刘炜 <liuwei@actions-semi.com>,
	"Jason Cooper" <jason@lakedaemon.net>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Gregory Clement" <gregory.clement@free-electrons.com>,
	"Sebastian Hesselbarth" <sebastian.hesselbarth@gmail.com>,
	"Neil Armstrong" <narmstrong@baylibre.com>,
	"Nicolas Ferre" <nicolas.ferre@microchip.com>
Subject: Re: [PATCH] ARM: owl: smp: Drop owl_secondary_boot()
Date: Thu, 6 Jul 2017 19:38:41 +0200	[thread overview]
Message-ID: <20170706173841.jwaskrrkooget6nk@piout.net> (raw)
In-Reply-To: <c037a437-0e9e-e451-d3a6-3a866db8bb16@suse.de>

On 06/07/2017 at 19:17:28 +0200, Andreas Färber wrote:
> Am 05.07.2017 um 04:36 schrieb Florian Fainelli:
> > On July 4, 2017 4:32:18 PM PDT, "Andreas Färber" <afaerber@suse.de> wrote:
> >> Commit 18cfd9429d8a82c49add8f3ca9d366599bfcac45 ("ARM: owl: smp: Drop
> >> bogus holding pen") simplified the S500 SMP code by removing a loop for
> >> pen_release in owl_secondary_boot(). Since then it is only calling
> >> owl_v7_invalidate_l1() before branching to secondary_startup().
> >>
> >> The owl_v7_invalidate_l1() assembler function is superfluous, too.
> >> Therefore drop owl_secondary_boot() and use secondary_boot() directly.
> >>
> >> Cc: David Liu <liuwei@actions-semi.com>
> >> Signed-off-by: Andreas Färber <afaerber@suse.de>
> >> ---
> > 
> >> -	writel(virt_to_phys(owl_secondary_startup),
> >> +	writel(virt_to_phys(secondary_startup),
> >> 	       timer_base_addr + OWL_CPU1_ADDR + (cpu - 1) * 4);
> > 
> > This is a kernel symbol so please use __pa_symbol() here, also you might want to build with CONFIG_DEBUG_VIRTUAL and see if you get other warnings about using virt_to_phys() in the owl platform code (I did not check if there are other uses)
> 
> Thanks for the report. There are no other such uses in mach-actions, but
> git-grep'ing for virt_to_phys in arch/arm/mach-* I spot at least one
> other such usage in mach-oxnas:
> 
> arch/arm/mach-oxnas/platsmp.c:
> writel(virt_to_phys(ox820_secondary_startup),
> 
> as well as this in mach-mvebu:
> 
> arch/arm/mach-mvebu/platsmp.c:  writel(virt_to_phys(boot_addr), base +
> MV98DX3236_CPU_RESUME_ADDR_REG);
> 
> and these in mach-at91:
> 
> arch/arm/mach-at91/pm.c:        pm_bu->canary = virt_to_phys(&canary);
> arch/arm/mach-at91/pm.c:        pm_bu->resume = virt_to_phys(cpu_resume);
> 

They can probably use __pa_symbol() (I must admit I didn't know about
it before this email)


-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com