Re: [PATCH v3 5/8] ARM: mediatek: add smp bringup code for MT6580

From: Scott Shu <scott.shu@mediatek.com>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Matthias Brugger <matthias.bgg@gmail.com>,
	Mark Rutland <mark.rutland@arm.com>, <devicetree@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-mediatek@lists.infradead.org>, <wsd_upstream@mediatek.com>,
	<loda.chou@mediatek.com>, <jades.shih@mediatek.com>,
	<Mars.Cheng@mediatek.com>, <scott.shu@gmail.com>
Subject: Re: [PATCH v3 5/8] ARM: mediatek: add smp bringup code for MT6580
Date: Fri, 7 Aug 2015 09:59:45 +0800	[thread overview]
Message-ID: <1438912785.1900.33.camel@mtkswgap22> (raw)
In-Reply-To: <20150806061918.GK18700@pengutronix.de>

On Thu, 2015-08-06 at 08:19 +0200, Sascha Hauer wrote:
> On Wed, Aug 05, 2015 at 06:47:03PM +0200, Matthias Brugger wrote:
> > On Tuesday, August 04, 2015 09:54:21 PM Scott Shu wrote:
> > > Add support for cpu enable-method "mediatek,mt6580-smp" for booting
> > > secondary CPUs on MT6580.
> > > 
> > > Signed-off-by: Scott Shu <scott.shu@mediatek.com>
> > > ---
> > >  arch/arm/mach-mediatek/platsmp.c |  137
> > > ++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+)
> > > +
> > > +static void __init mt6580_smp_prepare_cpus(unsigned int max_cpus)
> > > +{
> > > +	static void __iomem *infracfg_ao_base;
> > > +
> > > +	infracfg_ao_base = ioremap(MT6580_INFRACFG_AO, 0x1000);
> > > +	if (!infracfg_ao_base) {
> > > +		pr_err("%s: Unable to map I/O memory\n", __func__);
> > > +		return;
> > > +	}
> > > +
> > > +	/* Enable bootrom power down mode */
> > > +	writel_relaxed(readl(infracfg_ao_base + 0x804) | SW_ROM_PD,
> > > +		       infracfg_ao_base + 0x804);
> > 
> > Please use a define for the offset.
> > I prefer to not cascade reads and writes but to use a temporary variable. But 
> > if this is fine with the kernel coding style (I doubt, but I'm not sure) then 
> > this is fine.
> 
> For what it's worth I also prefer
> 
> 	val = readl(infracfg_ao_base + 0x804);
> 	val |= SW_ROM_PD:
> 	writel_relaxed(val, infracfg_ao_base + 0x804);
> 
> I find this better readable. I don't think though that there's common
> agreement that this style is better.
> 
> Sascha
> 
Fixed in next version. Thanks.

Scott