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

[Suzuki K Poulose]

On 10/03/2019 11:20 AM, Daniel Thompson wrote:
> 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@xxxxxxxxxxxxxx> wrote:
> > > On 2019-10-01 11:01, Jeffrey Hugo wrote:
> > > > On Tue, Oct 1, 2019 at 11:52 AM Sai Prakash Ranjan
> > > > <saiprakash.ranjan@xxxxxxxxxxxxxx> 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@xxxxxxxxx>
> > > > Tested-by: Jeffrey Hugo <jeffrey.l.hugo@xxxxxxxxx>
> > >
> > > 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 ?

Or like Mathieu said, all the Coresight specific nodes could be moved in
to say, msm8998-coresight.dtsi and could be included into the platforms
where it actually works.

Suzuki