Re: [PATCH 3/9] coresight-tpdm: Initialize DSB subunit configuration

[Suzuki K Poulose]

On 26/10/2022 09:10, Tao Zhang wrote:
> Hi Suzuki,
>
> 在 10/24/2022 6:02 PM, Suzuki K Poulose 写道:
> > Hi
> >
> > On 08/09/2022 09:44, Tao Zhang wrote:
> > > DSB subunit need to be configured in enablement and disablement.
> > > A struct that specifics associated to dsb dataset is needed. It
> > > saves the configuration and parameters of the dsb datasets. This
> > > change is to add this struct and initialize the configuration of
> > > DSB subunit.
> > >
> > > Signed-off-by: Tao Zhang <quic_taozha@xxxxxxxxxxx>
> > > ---
> > >   drivers/hwtracing/coresight/coresight-tpdm.c | 44 
> > > ++++++++++++++++++++++++++--
> > >   drivers/hwtracing/coresight/coresight-tpdm.h | 17 +++++++++++
> > >   2 files changed, 58 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c 
> > > b/drivers/hwtracing/coresight/coresight-tpdm.c
> > > index 88df3e6..69ea453 100644
> > > --- a/drivers/hwtracing/coresight/coresight-tpdm.c
> > > +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
> > > @@ -24,6 +24,22 @@ static void tpdm_enable_dsb(struct tpdm_drvdata 
> > > *drvdata)
> > >   {
> > >       u32 val;
> > >   +    val = readl_relaxed(drvdata->base + TPDM_DSB_TIER);
> > > +    /* Set trigger timestamp */
> > > +    if (drvdata->dsb->trig_ts)
> >
> > What happens if this instance doesn't have a DSB set ? Have
> > you tested this on a system without the DSB ?
> The function "tpdm_enable_dsb" will only be called when it is checked 
> that the DSB dataset is present.
>
> And only the TPDM that supports the DSB dataset will have the DSB TIER 
> register.
>
> If the TPDM doesn't support the DSB dataset, this instance should not be 
> run. Otherwise, it will cause that the incorrect register is accessed.

Thanks, this is what happens when you send something that is not queued
anywhwere. Please provide a reference tree in the future, for ease of
reviewing such things

Suzuki