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

[Yushan Wang <wangyushan12@huawei.com>]

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@huawei.com>
> ---
>  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@huawei.com>

>
>
>       /* 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
>  };
>

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