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Message-ID: <14a10466-3241-4375-f795-92cd155b27d7@quicinc.com>
Date:   Fri, 26 May 2023 11:22:00 +0800
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Subject: Re: [PATCH v4 02/11] coresight-tpda: Add DSB dataset support
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To:     Suzuki K Poulose <suzuki.poulose@arm.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Konrad Dybcio <konradybcio@gmail.com>,
        Mike Leach <mike.leach@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
CC:     Jinlong Mao <quic_jinlmao@quicinc.com>,
        Leo Yan <leo.yan@linaro.org>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        <coresight@lists.linaro.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        Tingwei Zhang <quic_tingweiz@quicinc.com>,
        Yuanfang Zhang <quic_yuanfang@quicinc.com>,
        Trilok Soni <quic_tsoni@quicinc.com>,
        Hao Zhang <quic_hazha@quicinc.com>,
        <linux-arm-msm@vger.kernel.org>, <andersson@kernel.org>
References: <1682586037-25973-1-git-send-email-quic_taozha@quicinc.com>
 <1682586037-25973-3-git-send-email-quic_taozha@quicinc.com>
 <444bc278-a3e3-7d99-6020-7c3337371f66@arm.com>
 <9c4c4ea0-b5dd-d18a-fadf-cd3a65c2cf5a@quicinc.com>
 <9f414290-0219-302f-ca8b-231217e68efb@arm.com>
From:   Tao Zhang <quic_taozha@quicinc.com>
In-Reply-To: <9f414290-0219-302f-ca8b-231217e68efb@arm.com>
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On 5/25/2023 5:08 PM, Suzuki K Poulose wrote:
> On 25/05/2023 08:16, Tao Zhang wrote:
>>
>> On 5/23/2023 6:07 PM, Suzuki K Poulose wrote:
>>> On 27/04/2023 10:00, Tao Zhang wrote:
>>>> Read the DSB element size from the device tree. Set the register
>>>> bit that controls the DSB element size of the corresponding port.
>>>>
>>>> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
>>>> ---
>>>>   drivers/hwtracing/coresight/coresight-core.c |  1 +
>>>>   drivers/hwtracing/coresight/coresight-tpda.c | 92 
>>>> +++++++++++++++++++++++++---
>>>>   drivers/hwtracing/coresight/coresight-tpda.h |  4 ++
>>>>   drivers/hwtracing/coresight/coresight-tpdm.c |  2 +-
>>>>   include/linux/coresight.h                    |  1 +
>>>>   5 files changed, 90 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/hwtracing/coresight/coresight-core.c 
>>>> b/drivers/hwtracing/coresight/coresight-core.c
>>>> index 2af416b..f1eacbb 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-core.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-core.c
>>>> @@ -1092,6 +1092,7 @@ static int coresight_validate_source(struct 
>>>> coresight_device *csdev,
>>>>         if (subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_PROC &&
>>>>           subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE &&
>>>> +        subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_TPDM &&
>>>>           subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_OTHERS) {
>>>>           dev_err(&csdev->dev, "wrong device subtype in %s\n", 
>>>> function);
>>>>           return -EINVAL;
>>>
>>> Please see the comment at the bottom.
>>>
>>>> diff --git a/drivers/hwtracing/coresight/coresight-tpda.c 
>>>> b/drivers/hwtracing/coresight/coresight-tpda.c
>>>> index 8d2b9d2..af9c72f 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-tpda.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-tpda.c
>>>> @@ -21,6 +21,56 @@
>>>>     DEFINE_CORESIGHT_DEVLIST(tpda_devs, "tpda");
>>>>   +/* Search and read element data size from the TPDM node in
>>>> + * the devicetree. Each input port of TPDA is connected to
>>>> + * a TPDM. Different TPDM supports different types of dataset,
>>>> + * and some may support more than one type of dataset.
>>>> + * Parameter "inport" is used to pass in the input port number
>>>> + * of TPDA, and it is set to 0 in the recursize call.
>>>> + * Parameter "parent" is used to pass in the original call.
>>>> + */
>>>> +static int tpda_set_element_size(struct tpda_drvdata *drvdata,
>>>> +               struct coresight_device *csdev, int inport, bool 
>>>> parent)
>>>> +{
>>>> +    static int nr_inport;
>>>> +    int i;
>>>> +    static bool tpdm_found;
>>>> +    struct coresight_device *in_csdev;
>>>> +
>>>> +    if (inport > (TPDA_MAX_INPORTS - 1))
>>>> +        return -EINVAL;
>>>> +
>>>> +    if (parent) {
>>>> +        nr_inport = inport;
>>>> +        tpdm_found = false;
>>>> +    }
>>>> +
>>>> +    for (i = 0; i < csdev->pdata->nr_inconns; i++) {
>>>> +        in_csdev = csdev->pdata->in_conns[i]->src_dev;
>>>> +        if (!in_csdev)
>>>> +            break;
>>>> +
>>>> +        if (parent)
>>>> +            if (csdev->pdata->in_conns[i]->dest_port != inport)
>>>> +                continue;
>>>> +
>>>> +        if (in_csdev->subtype.source_subtype
>>>
>>> We must match the in_csdev->type to be SOURCE && the subtype.
>> Sure, I will update it in the next patch series.
>>>
>>>> +                   == CORESIGHT_DEV_SUBTYPE_SOURCE_TPDM) {
>>>> + of_property_read_u8(in_csdev->dev.parent->of_node,
>>>> +                    "qcom,dsb-element-size", 
>>>> &drvdata->dsb_esize[nr_inport]);
>>>> +            if (!tpdm_found)
>>>> +                tpdm_found = true;
>>>> +            else
>>>> +                dev_warn(drvdata->dev,
>>>> +                    "More than one TPDM is mapped to the TPDA 
>>>> input port %d.\n",
>>>> +                    nr_inport);
>>>
>>> When we know, we have found a source device, we don't need to recurse
>>> down and could simply 'continue' to the next one in the list and skip
>>> the call below.
>>
>> Actually, one input port on TPDA only can connect to one TPDM. In the 
>> current design, it will
>>
>> find out all the TPDMs on one input port and warn the users all the 
>> TPDMs it found. If we
>>
>> replace 'recurse down' as 'continue' here, it may not find some TPDMs 
>> that might be connected
>>
>> incorrectly.
>
>
> What do you mean ? When you enter the if () above, the in_csdev is a
> source and it is TPDM. There must be no input connections TPDM, i.e.
> in_csdev, so no need to go further up the connection chain looking at
> the in_csdev. The loop will continue to analyse this device (where we
> found one TPDM already) and detect any further duplicate TPDMs
> connected.

Got it. You're right.

I will update this in the next patch series as well.

>
> Suzuki
>
>