linux-kernel - Re: [PATCH V2] spmi: pmic-arb: Enforce the ownership check optionally

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Date:   Tue, 22 Aug 2017 17:01:40 +0800
From:   Shawn Guo <shawnguo@...nel.org>
To:     Stephen Boyd <sboyd@...eaurora.org>
Cc:     Kiran Gunda <kgunda@...eaurora.org>, gregkh@...uxfoundation.org,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Abhijeet Dharmapurikar <adharmap@...eaurora.org>,
        David Collins <collinsd@...eaurora.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH V2] spmi: pmic-arb: Enforce the ownership check optionally

On Mon, Aug 21, 2017 at 04:18:58PM -0700, Stephen Boyd wrote:
> On 08/18/2017 08:28 AM, Kiran Gunda wrote:
> > The peripheral ownership check is not necessary on single master
> > platforms. Hence, enforce the peripheral ownership check optionally.
> >
> > Signed-off-by: Kiran Gunda <kgunda@...eaurora.org>
> > Tested-by: Shawn Guo <shawnguo@...nel.org>
> > ---
> 
> This sounds like a band-aid. Isn't the gpio driver going to keep probing
> all the pins that are not supposed to be accessed due to security
> constraints? What exactly is failing in the gpio case?
> 
> Also, I thought we were getting rid of the ownership checks? Or at
> least, putting them behind some debug kernel feature check or something?

I'm wondering that too.  Since we have the following patch to remove the
check on read/write access anyway, why are we adding the check in .xlate
hook?

spmi: pmic-arb: remove the read/write access checks

Shawn