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Date:   Mon, 10 Dec 2018 15:51:32 -0700
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Leo Yan <leo.yan@linaro.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Coresight ML <coresight@lists.linaro.org>,
        Mike Leach <mike.leach@linaro.org>,
        Robert Walker <robert.walker@arm.com>
Subject: Re: [PATCH v2 3/6] perf cs-etm: Rename CS_ETM_TRACE_ON to
 CS_ETM_DISCONTINUITY
Message-ID: <20181210225132.GB12152@xps15>
References: <1544431981-24144-1-git-send-email-leo.yan@linaro.org>
 <1544431981-24144-4-git-send-email-leo.yan@linaro.org>
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Hi Leo,

On Mon, Dec 10, 2018 at 04:52:58PM +0800, Leo Yan wrote:
> TRACE_ON element is used at the beginning of trace, it also can be
> appeared in the middle of trace data to indicate discontinuity; for
> example, it's possible to see multiple TRACE_ON elements in the trace
> stream if the trace is being limited by address range filtering.
> 
> Furthermore, except TRACE_ON element is for discontinuity, NO_SYNC and
> EO_TRACE also can be used to indicate discontinuity, though they are
> used for different scenarios for trace is interrupted.
> 
> This patch is to rename sample type CS_ETM_TRACE_ON to
> CS_ETM_DISCONTINUITY, firstly the new name describes more closely the
> purpose of the packet; secondly this is a preparation for other output
> elements which also cause the trace discontinuity thus they can share
> the same one packet type.
> 
> This patch also refactors the enumerations in cs_etm_sample_type by
> converting from bit shifting value to continuous numbers.
> 
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Mike Leach <mike.leach@linaro.org>
> Cc: Robert Walker <robert.walker@arm.com>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
>  tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 10 +++++-----
>  tools/perf/util/cs-etm-decoder/cs-etm-decoder.h |  6 +++---
>  tools/perf/util/cs-etm.c                        | 12 ++++++------
>  3 files changed, 14 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> index 0b4c862..a3994f1 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c
> @@ -391,11 +391,11 @@ cs_etm_decoder__buffer_range(struct cs_etm_decoder *decoder,
>  }
>  
>  static ocsd_datapath_resp_t
> -cs_etm_decoder__buffer_trace_on(struct cs_etm_decoder *decoder,
> -				const uint8_t trace_chan_id)
> +cs_etm_decoder__buffer_discontinuity(struct cs_etm_decoder *decoder,
> +					   const uint8_t trace_chan_id)
>  {
>  	return cs_etm_decoder__buffer_packet(decoder, trace_chan_id,
> -					     CS_ETM_TRACE_ON);
> +					     CS_ETM_DISCONTINUITY);
>  }
>  
>  static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
> @@ -414,8 +414,8 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer(
>  		decoder->trace_on = false;
>  		break;
>  	case OCSD_GEN_TRC_ELEM_TRACE_ON:
> -		resp = cs_etm_decoder__buffer_trace_on(decoder,
> -						       trace_chan_id);
> +		resp = cs_etm_decoder__buffer_discontinuity(decoder,
> +							    trace_chan_id);
>  		decoder->trace_on = true;
>  		break;
>  	case OCSD_GEN_TRC_ELEM_INSTR_RANGE:
> diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> index b295dd2..a272317 100644
> --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.h
> @@ -23,9 +23,9 @@ struct cs_etm_buffer {
>  };
>  
>  enum cs_etm_sample_type {
> -	CS_ETM_EMPTY = 0,
> -	CS_ETM_RANGE = 1 << 0,
> -	CS_ETM_TRACE_ON = 1 << 1,
> +	CS_ETM_EMPTY,
> +	CS_ETM_RANGE,
> +	CS_ETM_DISCONTINUITY,
>  };

I'm in agreement with what you're doing in this patch but the above is a
different change and you can't pack it in here.  Just split it off in a separate
patch and everything will be fine.

>  
>  enum cs_etm_isa {
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index ffc4fe5..cea3158 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -562,8 +562,8 @@ static inline int cs_etm__t32_instr_size(struct cs_etm_queue *etmq,
>  
>  static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
>  {
> -	/* Returns 0 for the CS_ETM_TRACE_ON packet */
> -	if (packet->sample_type == CS_ETM_TRACE_ON)
> +	/* Returns 0 for the CS_ETM_DISCONTINUITY packet */
> +	if (packet->sample_type == CS_ETM_DISCONTINUITY)
>  		return 0;
>  
>  	return packet->start_addr;
> @@ -572,8 +572,8 @@ static inline u64 cs_etm__first_executed_instr(struct cs_etm_packet *packet)
>  static inline
>  u64 cs_etm__last_executed_instr(const struct cs_etm_packet *packet)
>  {
> -	/* Returns 0 for the CS_ETM_TRACE_ON packet */
> -	if (packet->sample_type == CS_ETM_TRACE_ON)
> +	/* Returns 0 for the CS_ETM_DISCONTINUITY packet */
> +	if (packet->sample_type == CS_ETM_DISCONTINUITY)
>  		return 0;
>  
>  	return packet->end_addr - packet->last_instr_size;
> @@ -972,7 +972,7 @@ static int cs_etm__sample(struct cs_etm_queue *etmq)
>  		bool generate_sample = false;
>  
>  		/* Generate sample for tracing on packet */
> -		if (etmq->prev_packet->sample_type == CS_ETM_TRACE_ON)
> +		if (etmq->prev_packet->sample_type == CS_ETM_DISCONTINUITY)
>  			generate_sample = true;
>  
>  		/* Generate sample for branch taken packet */
> @@ -1148,7 +1148,7 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
>  					 */
>  					cs_etm__sample(etmq);
>  					break;
> -				case CS_ETM_TRACE_ON:
> +				case CS_ETM_DISCONTINUITY:
>  					/*
>  					 * Discontinuity in trace, flush
>  					 * previous branch stack
> -- 
> 2.7.4
>