Re: [PATCH 1/5] soc: mediatek: Add SMI driver

From: Paul Bolle <pebolle@tiscali.nl>
To: Yong Wu <yong.wu@mediatek.com>
Cc: Rob Herring <robh+dt@kernel.org>, Joerg Roedel <joro@8bytes.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Daniel Kurtz <djkurtz@google.com>, Tomasz Figa <tfiga@google.com>,
	Lucas Stach <l.stach@pengutronix.de>,
	Mark Rutland <mark.rutland@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	linux-mediatek@lists.infradead.org,
	Sasha Hauer <kernel@pengutronix.de>,
	srv_heupstream@mediatek.com, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	iommu@lists.linux-foundation.org
Subject: Re: [PATCH 1/5] soc: mediatek: Add SMI driver
Date: Mon, 09 Mar 2015 18:59:37 +0100	[thread overview]
Message-ID: <1425923977.2317.4.camel@tiscali.nl> (raw)
In-Reply-To: <1425902271.13300.18.camel@mhfsdcap03>

Hi Yong,

Yong Wu schreef op ma 09-03-2015 om 19:57 [+0800]:
> On Fri, 2015-03-06 at 12:30 +0100, Paul Bolle wrote:
> > On Fri, 2015-03-06 at 18:48 +0800, yong.wu@mediatek.com wrote:
> > > --- a/drivers/soc/mediatek/Kconfig
> > > +++ b/drivers/soc/mediatek/Kconfig
> > > @@ -20,3 +20,10 @@ config MT8173_PMIC_WRAP
> > >  	  PMIC wrapper is a proprietary hardware in MT8173 to make
> > >  	  communication protocols to access PMIC device.
> > >  	  This driver implement access protocols for MT8173.
> > > +
> > > +config MTK_SMI
> > > +        bool
> > 
> > Nit: make this one tab instead of 8 spaces, please.
> > 
> > > +	help
> > > +	  Smi help enable/disable iommu in mt8173 and control the
> > > +	  clock of each local arbiter.
> > > +	  It should be true while MTK_IOMMU enable.
> > 
> > I don't think anyone using the *config tools will ever see this text, as
> > there's no prompt. So you might as well make this a comment or drop it
> > altogether.
> > 
>      We could search it in the tool even though we don't see it. In next
> version, I will try to make it a comment.
> > Is this selected by more than just MTK_IOMMU (see 2/5)? If not, I think
> > MTK_SMI will be set and unset in lockstep with MTK_IOMMU. In other
> > words, you could as well use one Kconfig symbol.
> > 
>     if we disable MTK_IOMMU, the MTK_SMI also should be selected.That is because 
> if the multimedia h/w want to work, the clock of the local arbiters always should be opened.

This is a bit confusing, I'm afraid. Do you mean to say that it ought to
be possible for MTK_SMI to be 'y' even if MTK_IOMMU would be 'n'?

Paul Bolle