Re: [PATCH v2 2/9] coresight-tpda: Add DSB dataset support

[Tao Zhang]

Hi Suzuki,

Currently if the dsb_esize is not set to 32 or 64, we will not set the 
DSBSIZE bit of the register here.

This design is really not good enough.

I will change this in the next version of patch to issue a warning if an 
unexpected value is obtained.

在 2/22/2023 8:46 PM, Suzuki K Poulose 写道:
> On 19/01/2023 07:41, Tao Zhang wrote:
> > Read the DSB element size from the device tree. Set the register
> > bit that controls the DSB element size of the corresponding port.
> >
> > Signed-off-by: Tao Zhang <quic_taozha@xxxxxxxxxxx>
> > Signed-off-by: Tao Zhang <taozha@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/hwtracing/coresight/coresight-tpda.c | 62 
> > ++++++++++++++++++++++++++++
> >   drivers/hwtracing/coresight/coresight-tpda.h |  4 ++
> >   2 files changed, 66 insertions(+)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-tpda.c 
> > b/drivers/hwtracing/coresight/coresight-tpda.c
> > index 5989798..be13e08 100644
> > --- a/drivers/hwtracing/coresight/coresight-tpda.c
> > +++ b/drivers/hwtracing/coresight/coresight-tpda.c
> > @@ -37,6 +37,15 @@ static void tpda_enable_port(struct tpda_drvdata 
> > *drvdata, int port)
> >       u32 val;
> >         val = readl_relaxed(drvdata->base + TPDA_Pn_CR(port));
> > +    /*
> > +     * Configure aggregator port n DSB data set element size
> > +     * Set the bit to 0 if the size is 32
> > +     * Set the bit to 1 if the size is 64
> > +     */
> > +    if (drvdata->dsb_esize[port] == 32)
> > +        val &= ~TPDA_Pn_CR_DSBSIZE;
> > +    else if (drvdata->dsb_esize[port] == 64)
> > +        val |= TPDA_Pn_CR_DSBSIZE;
>
> What are the chances of having a value other than 32 or 64 ?
> What should we do in that case ? Should the driver at least
> give out a warning at least in the unhandled case rather than
> silently reusing the existing setting ?
>
> Suzuki
Best,

Tao