linux-kernel - Re: [PATCHv9 2/3] arm64: dts: qcom: msm8998: Add Coresight support

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Date:   Thu, 3 Oct 2019 11:20:23 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Jeffrey Hugo <jeffrey.l.hugo@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        MSM <linux-arm-msm@...r.kernel.org>,
        Marc Gonzalez <marc.w.gonzalez@...e.fr>,
        lkml <linux-kernel@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        Leo Yan <leo.yan@...aro.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCHv9 2/3] arm64: dts: qcom: msm8998: Add Coresight support

On Wed, Oct 02, 2019 at 09:03:59AM -0600, Mathieu Poirier wrote:
> On Tue, 1 Oct 2019 at 12:05, Sai Prakash Ranjan
> <saiprakash.ranjan@...eaurora.org> wrote:
> >
> > On 2019-10-01 11:01, Jeffrey Hugo wrote:
> > > On Tue, Oct 1, 2019 at 11:52 AM Sai Prakash Ranjan
> > > <saiprakash.ranjan@...eaurora.org> wrote:
> > >>
> > >>
> > >> Haan then likely it's the firmware issue.
> > >> We should probably disable coresight in soc dtsi and enable only for
> > >> MTP. For now you can add a status=disabled for all coresight nodes in
> > >> msm8998.dtsi and I will send the patch doing the same in a day or
> > >> two(sorry I am travelling currently).
> > >
> > > This sounds sane to me (and is what I did while bisecting the issue).
> > > When you do create the patch, feel free to add the following tags as
> > > you see fit.
> > >
> > > Reported-by: Jeffrey Hugo <jeffrey.l.hugo@...il.com>
> > > Tested-by: Jeffrey Hugo <jeffrey.l.hugo@...il.com>
> >
> > Thanks Jeffrey, I will add them.
> > Hope Mathieu and Suzuki are OK with this.
> 
> The problem here is that a debug and production device are using the
> same device tree, i.e msm8998.dtsi.  Disabling coresight devices in
> the DTS file will allow the laptop to boot but completely disabled
> coresight blocks on the MTP board.  Leaving things as is breaks the
> laptop but allows coresight to be used on the MTP board.  One of three
> things can happen:
> 
> 1) Nothing gets done and production board can't boot without DTS modifications.
> 2) Disable tags are added to the DTS file and the debug board can't
> use coresight without modifications.
> 2) The handling of the debug power domain is done properly on the
> MSM8998 rather than relying on the bootloader to enable it.
> 3) The DTS file is split or reorganised to account for debug/production devices.

msm8998.dtsi is a SoC include file. Can't whatever default it adopts be
reversed in the board include files such as msm8998-mtp.dtsi or
msm8998-clamshell.dtsi ?


Daniel.