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

[Jeffrey Hugo]

On Tue, Oct 1, 2019 at 11:52 AM Sai Prakash Ranjan
<saiprakash.ranjan@xxxxxxxxxxxxxx> wrote:
>
> On 2019-10-01 10:14, Jeffrey Hugo wrote:
> > On Tue, Oct 1, 2019 at 11:04 AM Sai Prakash Ranjan
> > <saiprakash.ranjan@xxxxxxxxxxxxxx> wrote:
> >>
> >> On 2019-10-01 09:13, Jeffrey Hugo wrote:
> >> > Sai,
> >> >
> >> > This patch breaks boot on the 835 laptops.  However, I haven't seen
> >> > the same issue on the MTP.  I wonder, is coresight expected to work
> >> > with production fused devices?  I wonder if thats the difference
> >> > between the laptop and MTP that is causing the issue.
> >> >
> >> > Let me know what I can do to help debug.
> >> >
> >>
> >> I did test on MSM8998 MTP and didn't face any issue. I am guessing
> >> this
> >> is the same issue which you reported regarding cpuidle? Coresight ETM
> >
> > Yes, its the same issue.  Right now, I need both patches reverted to
> > boot.
> >
> >> and cpuidle do not work well together since ETMs share the same power
> >> domain as CPU and they might get turned off when CPU enters idle
> >> states.
> >> Can you try with cpuidle.off=1 cmdline or just remove idle states from
> >> DT to confirm? If this is the issue, then we can try the below patch
> >> from Andrew Murray for ETM save and restore:
> >>
> >> https://patchwork.kernel.org/patch/11097893/
> >
> > Is there still value in testing this if the idle states are removed,
> > yet the coresight nodes still cause issues?
> >
> > Funny enough, I'm using the arm64 defconfig which doesn't seem to
> > select CONFIG_CORESIGHT, so I'm not even sure what would be binding to
> > the DT devices...
> >
>
> 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>