linux-kernel - Re: [PATCH v5 6/9] coresight: add support for CPU debug module

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Message-ID: <b3bed726-921c-0f5c-8b51-2beaa19921c9@arm.com>
Date:   Thu, 30 Mar 2017 16:47:59 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Mike Leach <mike.leach@...aro.org>, Leo Yan <leo.yan@...aro.org>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Wei Xu <xuwei5@...ilicon.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Guodong Xu <guodong.xu@...aro.org>,
        John Stultz <john.stultz@...aro.org>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-clk@...r.kernel.org,
        "Suzuki K. Poulose" <Suzuki.Poulose@....com>
Subject: Re: [PATCH v5 6/9] coresight: add support for CPU debug module



On 29/03/17 15:56, Mike Leach wrote:

[...]
> 
> No - EDPRCR_COREPURQ and EDPRCR_CORENPDRQ have different semantics and purposes
> 
> EDPRCR_COREPURQ is in the debug power domain an is tied to an external
> debug request that should be an input to the external (to the PE)
> system power controller.
> The requirement is that the system power controller powers up the core
> domain and does not power it down while it remains asserted.
> 
> EDPRCR_CORENPDRQ is in the core power domain and thus to the specific
> core only. This ensures that any power control software running on
> that core should emulate a power down if this is set to one.
> 
> We cannot know the power control design of the system, so the safe
> solution is to set both bits.
> 

+1

I agree that's the safe bet.

-- 
Regards,
Sudeep