Re: [PATCH] coresight: etm4x: Skip setting LPOVERRIDE bit for qcom,skip-power-up

[Suzuki Poulose]

On 10/16/20 12:47 PM, Sai Prakash Ranjan wrote:
> Hi Suzuki,
>
> On 2020-10-16 16:51, Suzuki Poulose wrote:
> > Hi Sai,
> >
> > On 10/16/20 11:10 AM, Sai Prakash Ranjan wrote:
> > > There is a bug on the systems supporting to skip power up
> > > (qcom,skip-power-up) where setting LPOVERRIDE bit(low-power
> > > state override behaviour) will result in CPU hangs/lockups
> > > even on the implementations which supports it. So skip
> > > setting the LPOVERRIDE bit for such platforms.
> > >
> > > Fixes: 02510a5aa78d ("coresight: etm4x: Add support to skip trace 
> > > unit power up")
> > > Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> >
> > The fix is fine by me. Btw, is there a hardware Erratum assigned for
> > this ? It would be good to have the Erratum documented somewhere,
> > preferrably ( Documentation/arm64/silicon-errata.rst )
>
> No, afaik we don't have any erratum assigned to this bug.

Ok. Please double check, if there are any.

> It was already present in downstream kernel and since we
> support these targets with the previous HW bug
> (qcom,skip-power-up) now in upstream, we would need this
> fix in upstream kernel as well.

I understand the need for the fix and we must fix it. I was
looking to document this in the central place for errata's
handled in the kernel. And I missed asking this question
when the original patch was posted. So, thought of asking
the question now anyways. Better late than never ;-)

Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>