Re: [PATCH v2 09/23] coresight: trbe: Clear TRBSR status at stop sites

[Leo Yan]

On Mon, Nov 09, 2026 at 10:51:30PM +0000, Suzuki K Poulose wrote:
> On 16/10/2026 17:55, Leo Yan wrote:
> > TRBSR_EL1 records the status of the buffer that just stopped. Clearing
> > it in trbe_enable_hw() postpones cleanup until another run starts. If
> > AUX output cannot restart, for example when AUX space is exhausted,
> > that clear never executes. Clear the status in arm_trbe_disable()
> > after disabling TRBE instead.
> > 
> > trbe_handle_overflow() can start the next run without calling
> > arm_trbe_disable(). Clear the stopped buffer's syndrome and status bits
> > while TRBE is disabled, before attempting the AUX restart. This also
> > leaves the status clean when the restart fails.
> > 
> > Signed-off-by: Leo Yan <leo.yan@xxxxxxx>
> > ---
> >   drivers/hwtracing/coresight/coresight-trbe.c | 10 +++++++++-
> >   1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> > index 26e7554d6bdd31f8a55a8bc3a7b6d4c49b984b9b..dd9c9330bb0c739795f300dafc6ce34e72fbf280 100644
> > --- a/drivers/hwtracing/coresight/coresight-trbe.c
> > +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> > @@ -655,7 +655,6 @@ static void trbe_enable_hw(struct trbe_buf *buf)
> >   	WARN_ON(buf->trbe_hw_base < buf->trbe_base);
> >   	WARN_ON(buf->trbe_write < buf->trbe_hw_base);
> >   	WARN_ON(buf->trbe_write >= buf->trbe_limit);
> > -	clr_trbe_status();
> 
> TRBSR_ELx is UNKNOWN at reset and if we don't clear it at probe time, we
> endup running the first session with unknown values. It is safer to
> clear this at enable_hw.

This is incorrect. trbe_reset_local() is called locally on each CPU to
clear TRBSR_ELx, it has been guaranteed when the first session starts.

Thanks,
Leo