linux-kernel - Re: [PATCH v2 4/8] coresight-tpdm: Add support to configure CMB

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Date:   Wed, 1 Nov 2023 17:06:51 +0800
From:   Tao Zhang <quic_taozha@...cinc.com>
To:     James Clark <james.clark@....com>
CC:     Jinlong Mao <quic_jinlmao@...cinc.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <coresight@...ts.linaro.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        Tingwei Zhang <quic_tingweiz@...cinc.com>,
        Yuanfang Zhang <quic_yuanfang@...cinc.com>,
        Trilok Soni <quic_tsoni@...cinc.com>,
        Song Chai <quic_songchai@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <andersson@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Konrad Dybcio <konradybcio@...il.com>,
        Mike Leach <mike.leach@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Subject: Re: [PATCH v2 4/8] coresight-tpdm: Add support to configure CMB


On 10/30/2023 7:29 PM, James Clark wrote:
>
> On 25/10/2023 03:53, Tao Zhang wrote:
>> TPDM CMB subunits support two forms of CMB data set element creation:
>> continuous and trace-on-change collection mode. Continuous change
>> creates CMB data set elements on every CMBCLK edge. Trace-on-change
>> creates CMB data set elements only when a new data set element differs
>> in value from the previous element in a CMB data set. Set CMB_CR.MODE
>> to 0 for continuous CMB collection mode. Set CMB_CR.MODE to 1 for
>> trace-on-change CMB collection mode
>>
>> Signed-off-by: Tao Zhang <quic_taozha@...cinc.com>
>> Signed-off-by: Jinlong Mao <quic_jinlmao@...cinc.com>
>> ---
>>   .../ABI/testing/sysfs-bus-coresight-devices-tpdm   | 10 +++
>>   drivers/hwtracing/coresight/coresight-tpdm.c       | 71 ++++++++++++++++++++++
>>   drivers/hwtracing/coresight/coresight-tpdm.h       | 12 ++++
>>   3 files changed, 93 insertions(+)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>> index f07218e..ace7231 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>> @@ -170,3 +170,13 @@ Contact:	Jinlong Mao (QUIC) <quic_jinlmao@...cinc.com>, Tao Zhang (QUIC) <quic_t
>>   Description:
>>   		(RW) Set/Get the MSR(mux select register) for the DSB subunit
>>   		TPDM.
>> +
>> +What:		/sys/bus/coresight/devices/<tpdm-name>/cmb_mode
>> +Date:		March 2023
>> +KernelVersion	6.7
>> +Contact:	Jinlong Mao (QUIC) <quic_jinlmao@...cinc.com>, Tao Zhang (QUIC) <quic_taozha@...cinc.com>
>> +Description:	(Write) Set the data collection mode of CMB tpdm.
> I know it's expanded elsewhere, but it's probably worth expanding the
> CMB abbreviation here as well so people reading the docs don't have to
> go into the code.

Sure, I will update in the next patch series.


Best,

Tao

>
> Otherwise:
>
> Reviewed-by: James Clark <james.clark@....com>
>
>> +
>> +		Accepts only one of the 2 values -  0 or 1.
>> +		0 : Continuous CMB collection mode.
>> +		1 : Trace-on-change CMB collection mode.
>> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c b/drivers/hwtracing/coresight/coresight-tpdm.c
>> index c8bb388..efb376e 100644
>> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
>> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
>> @@ -148,6 +148,18 @@ static umode_t tpdm_dsb_is_visible(struct kobject *kobj,
>>   	return 0;
>>   }
> [...]