Re: [PATCH v4 04/11] coresight-tpdm: Add reset node to TPDM node

[Tao Zhang]

On 5/23/2023 10:53 PM, Suzuki K Poulose wrote:
> On 27/04/2023 10:00, Tao Zhang wrote:
> > TPDM device need a node to reset the configurations and status of
> > it. This change provides a node to reset the configurations and
> > disable the TPDM if it has been enabled.
> >
> > Signed-off-by: Tao Zhang <quic_taozha@xxxxxxxxxxx>
> > ---
> >   .../ABI/testing/sysfs-bus-coresight-devices-tpdm   | 10 ++++++++
> >   drivers/hwtracing/coresight/coresight-tpdm.c       | 27 
> > ++++++++++++++++++++++
> >   2 files changed, 37 insertions(+)
> >
> > diff --git 
> > a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm 
> > b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> > index 4a58e64..686bdde 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> > +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
> > @@ -11,3 +11,13 @@ Description:
> >           Accepts only one of the 2 values -  1 or 2.
> >           1 : Generate 64 bits data
> >           2 : Generate 32 bits data
> > +
> > +What:        /sys/bus/coresight/devices/<tpdm-name>/reset
> > +Date:        March 2023
> > +KernelVersion    6.3
> > +Contact:    Jinlong Mao (QUIC) <quic_jinlmao@xxxxxxxxxxx>, Tao Zhang 
> > (QUIC) <quic_taozha@xxxxxxxxxxx>
> > +Description:
> > +        (Write) Reset the dataset of the tpdm, and disable the tpdm.
> > +
> > +        Accepts only one value -  1.
> > +        1 : Reset the dataset of the tpdm
> > diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c 
> > b/drivers/hwtracing/coresight/coresight-tpdm.c
> > index 6f8a8ab..2e64cfd 100644
> > --- a/drivers/hwtracing/coresight/coresight-tpdm.c
> > +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
> > @@ -164,6 +164,32 @@ static int tpdm_datasets_setup(struct 
> > tpdm_drvdata *drvdata)
> >       return 0;
> >   }
> >   +static ssize_t reset_store(struct device *dev,
> > +                      struct device_attribute *attr,
> > +                      const char *buf,
> > +                      size_t size)
> > +{
> > +    int ret = 0;
> > +    unsigned long val;
> > +    struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > +
> > +    ret = kstrtoul(buf, 10, &val);
> > +    if (ret || val != 1)
> > +        return -EINVAL;
> > +
> > +    spin_lock(&drvdata->spinlock);
> > +    tpdm_reset_datasets(drvdata);
> > +
> > +    spin_unlock(&drvdata->spinlock);
> > +
> > +    /* Disable tpdm if enabled */
> > +    if (drvdata->enable)
> > +        coresight_disable_source(drvdata->csdev, NULL);
>
> I am not really keen on doing this behind the back. What about the 
> path of components ? We could simply reject the request when the TPDA 
> is enabled and let the user alway follow :
>     1) Disable the TPDM manually via sysfs
>       2) Reset the TPDM.
>
> So, please remove the disable step here.

I will update this in the next patch series.

Best,

Tao

> Suzuki
>
>
> > +
> > +    return size;
> > +}
> > +static DEVICE_ATTR_WO(reset);
> > +
> >   /*
> >    * value 1: 64 bits test data
> >    * value 2: 32 bits test data
> > @@ -204,6 +230,7 @@ static ssize_t integration_test_store(struct 
> > device *dev,
> >   static DEVICE_ATTR_WO(integration_test);
> >     static struct attribute *tpdm_attrs[] = {
> > +    &dev_attr_reset.attr,
> >       &dev_attr_integration_test.attr,
> >       NULL,
> >   };