linux-kernel - Re: [PATCH 1/2] socfpga: hotplug: put cpu1 in wfi

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Date:	Wed, 1 Oct 2014 09:17:18 -0500
From:	atull <atull@...nsource.altera.com>
To:	Pavel Machek <pavel@...x.de>
CC:	<dinguyen@...nsource.altera.com>, <linux@....linux.org.uk>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <delicious.quinoa@...il.com>,
	<yvanderv@...nsource.altera.com>
Subject: Re: [PATCH 1/2] socfpga: hotplug: put cpu1 in wfi

On Wed, 1 Oct 2014, Pavel Machek wrote:

> Hi!
> 
> > From: Alan Tull <atull@...nsource.altera.com>
> > 
> > Use WFI when putting CPU1 to sleep.  Don't hold CPU1 in reset
> > since that results in increased power consumption.
> > 
> > Reset CPU1 briefly during CPU1 bootup.
> > 
> > This has been tested for hotplug and suspend/resume and results
> > in no increased power consumption.
> > 
> > Signed-off-by: Alan Tull <atull@...nsource.altera.com>
> > ---
> >  arch/arm/mach-socfpga/core.h    |    2 ++
> >  arch/arm/mach-socfpga/platsmp.c |   12 +++++++++---
> >  2 files changed, 11 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/arm/mach-socfpga/core.h b/arch/arm/mach-socfpga/core.h
> > index 572b8f7..c4a0929 100644
> > --- a/arch/arm/mach-socfpga/core.h
> > +++ b/arch/arm/mach-socfpga/core.h
> > @@ -28,6 +28,8 @@
> >  #define RSTMGR_CTRL_SWCOLDRSTREQ	0x1	/* Cold Reset */
> >  #define RSTMGR_CTRL_SWWARMRSTREQ	0x2	/* Warm Reset */
> >  
> > +#define RSTMGR_MPUMODRST_CPU1		0x2     /*CPU1 Reset*/
> > +
> 
> It would be nice to have space after /* and before */.

Hi Pavel,

I will fix the comment space here and the other place you pointed out.

> 
> > diff --git a/arch/arm/mach-socfpga/platsmp.c b/arch/arm/mach-socfpga/platsmp.c
> > index 5356a72..1d5f8ad 100644
> > --- a/arch/arm/mach-socfpga/platsmp.c
> > +++ b/arch/arm/mach-socfpga/platsmp.c
> > @@ -34,6 +34,10 @@ static int socfpga_boot_secondary(unsigned int cpu, struct task_struct *idle)
> >  	int trampoline_size = &secondary_trampoline_end - &secondary_trampoline;
> >  
> >  	if (cpu1start_addr) {
> > +		/* This will put CPU #1 into reset.*/
> 
> Same here.
> 
> > +		__raw_writel(RSTMGR_MPUMODRST_CPU1,
> > +			     rst_manager_base_addr + 0x10);
> 
> Would it be possible to copy reset manager description struct from
> u-boot and use it here, instead of raw offset?

I will replace this 0x10 with a macro that reflects how the register is 
named in the register map.

Thanks for the review!

Alan

> 								Pavel
> -- 
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
> 
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