Re: [PATCH v2 7/8] hwtracing: hisi_ptt: Add pattern PMU config for trace format selection

[Sizhe Liu]

On 2026/9/1 9:31, Yushan Wang wrote:
> On 8/27/2026 10:04 PM, Sizhe Liu wrote:
> > Introduce a `pattern` PMU config field (config:36-39) that controls
> > which TLP header format the hardware traces. bit[3:1] are reserved for
> > future extension and only bit0 is used currently:
> >
> > - pattern=0 (default, compatibility mode): the driver sets bit[8] of
> >     HISI_PTT_TRACE_CTRL so the hardware traces the data in compatibility
> >     mode.
> > - pattern=1: the driver clears bit[8] of HISI_PTT_TRACE_CTRL so the
> >     hardware traces the data pattern including some bitfields of the TLP
> >     header defined in PCIe r6.4 sec 2.2.1.2.
> >
> > Note that bit[8] of HISI_PTT_TRACE_CTRL is inverted with respect to the
> > `pattern` value: bit[8]=1 selects the legacy format, bit[8]=0 selects
> > the new format. Bit[11:9] is still reserved, which is consistent with the
> > PMU config field. The driver validates the 4-bit value in
> > hisi_ptt_trace_valid_pattern() and applies it in hisi_ptt_trace_start().
> >
> > Document the new parameter in Documentation/trace/hisi-ptt.rst.
> >
> > Signed-off-by: Sizhe Liu <liusizhe5@xxxxxxxxxx>
> > ---
> >    Documentation/trace/hisi-ptt.rst | 25 +++++++++++++++++++++++--
> >    drivers/hwtracing/ptt/hisi_ptt.c | 25 ++++++++++++++++++++++++-
> >    drivers/hwtracing/ptt/hisi_ptt.h |  4 ++++
> >    3 files changed, 51 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/trace/hisi-ptt.rst b/Documentation/trace/hisi-ptt.rst
> > index f6a2655f99e5..c95eaa12f4d3 100644
> > --- a/Documentation/trace/hisi-ptt.rst
> > +++ b/Documentation/trace/hisi-ptt.rst
> > @@ -255,7 +255,28 @@ directly from the TLP header.
> >         DW2 [                     Header DW2                            ]
> >         DW3 [                     Header DW3                            ]
> >
> > -5. Memory Management
> > +5. Trace pattern
> > +-----------------
> > +
> > +You can control whether the trace is taken with the new version of the
> > +TLP header format by specifying the `pattern` parameter. The default
> > +value is 0, which means the legacy format is used for backward
> > +compatibility. The parameter value is 4 bit and bit[3:1] are currently
> > +reserved for extension. Current supported values are shown below:
> > +
> > +- 4'b0000: legacy trace format
> > +    DW2 and DW3 are printed with generic field names only, and
> > +    no message-type-basedfield decoding.
> > +- 4'b0001: trace format v1
> > +    DW2 and DW3 are decoded according to the TLP message type (MWr,
> > +    Msg, Atomic, IO, CPL, Cfg) with detailed field names. It is recommended to
> > +    use trace format v1 when the current PCIe link generation is higher than
> > +    PCIe 6.0.
> > +
> > +For trace data recorded by an older tracer without the `pattern` parameter,
> > +the decoder will work as `pattern` forced to 0.
> > +
> > +6. Memory Management
> >    --------------------
> >
> >    The traced TLP headers will be written to the memory allocated
> > @@ -274,7 +295,7 @@ will commit the AUX buffer first and then apply for a new one with
> >    the same size. The size of AUX buffer is default to 16MiB. User can
> >    adjust the size by specifying the `-m` parameter of the perf command.
> >
> > -6. Decoding
> > +7. Decoding
> >    -----------
> >
> >    You can decode the traced data with `perf report -D` command (currently
> > diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c
> > index 94c371c49135..1696c30ac4c9 100644
> > --- a/drivers/hwtracing/ptt/hisi_ptt.c
> > +++ b/drivers/hwtracing/ptt/hisi_ptt.c
> > @@ -233,6 +233,10 @@ static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
> >         val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_TARGET_SEL, hisi_ptt->trace_ctrl.filter);
> >         if (!hisi_ptt->trace_ctrl.is_port)
> >                 val |= HISI_PTT_TRACE_CTRL_FILTER_MODE;
> > +     if (!ctrl->pattern)
> > +             val |= HISI_PTT_TRACE_CTRL_PATTERN;
> > +     else
> > +             val &= ~HISI_PTT_TRACE_CTRL_PATTERN;
>
> Hi Sizhe,
>
> This hunk seems not able to be applied to mainstream cleanly, otherwise
> this series LGTM.
>
> Reviewed-by: Yushan Wang <wangyushan12@xxxxxxxxxx>
Hi Yushan,

I will fix it in v3. Thanks for your Reviewed-by tag.

Regards,
Sizhe >>
> >         /* Start the Trace */
> >         val |= HISI_PTT_TRACE_CTRL_EN;
> > @@ -805,12 +809,14 @@ PMU_FORMAT_ATTR(filter,         "config:0-19");
> >    PMU_FORMAT_ATTR(direction,   "config:20-23");
> >    PMU_FORMAT_ATTR(type,                "config:24-31");
> >    PMU_FORMAT_ATTR(format,              "config:32-35");
> > +PMU_FORMAT_ATTR(pattern,             "config:36-39");
> >
> >    static struct attribute *hisi_ptt_pmu_format_attrs[] = {
> >         &format_attr_filter.attr,
> >         &format_attr_direction.attr,
> >         &format_attr_type.attr,
> >         &format_attr_format.attr,
> > +     &format_attr_pattern.attr,
> >         NULL
> >    };
>
> [...]