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

[Sai Prakash Ranjan]

Hi Suzuki,

On 2020-10-16 18:45, Suzuki Poulose wrote:
> 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.

Sure I will check again.

> > 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>

Thanks. One more thing, does the internal erratum
number (if it exists) is good enough to be documented in
the Documentation/arm64/silicon-errata.rst ? I ask this
because outside qualcomm, it won't mean much right.

Thanks,
Sai

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