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

From: Daniel Thompson <daniel.thompson@linaro.org>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
	Jeffrey Hugo <jeffrey.l.hugo@gmail.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Rajendra Nayak <rnayak@codeaurora.org>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	MSM <linux-arm-msm@vger.kernel.org>,
	Marc Gonzalez <marc.w.gonzalez@free.fr>,
	lkml <linux-kernel@vger.kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	David Brown <david.brown@linaro.org>,
	Andy Gross <agross@kernel.org>,
	Sibi Sankar <sibis@codeaurora.org>, Leo Yan <leo.yan@linaro.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	linux-arm-msm-owner@vger.kernel.org
Subject: Re: [PATCHv9 2/3] arm64: dts: qcom: msm8998: Add Coresight support
Date: Thu, 3 Oct 2019 11:20:23 +0100	[thread overview]
Message-ID: <20191003102023.qk6ik5vmatheaofs@holly.lan> (raw)
In-Reply-To: <CANLsYkxPOOorqcnPrbhZLzGV9Y7EGWUUyxvi-Cm5xxnzhx=Ecg@mail.gmail.com>

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@codeaurora.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@codeaurora.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@gmail.com>
> > > Tested-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.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.