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Message-ID: <fa39e477-7faf-46e4-8ae2-9eb2321afc26@arm.com>
Date: Tue, 19 Dec 2023 13:54:00 +0000
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User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v3 2/8] coresight-tpda: Add support to configure CMB
 element
Content-Language: en-GB
To: Tao Zhang <quic_taozha@quicinc.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>, Song Chai <quic_songchai@quicinc.com>,
 linux-arm-msm@vger.kernel.org, andersson@kernel.org
References: <1700533494-19276-1-git-send-email-quic_taozha@quicinc.com>
 <1700533494-19276-3-git-send-email-quic_taozha@quicinc.com>
 <88e51407-344e-4584-8711-29cc014c782b@arm.com>
 <b5965008-b51d-4bb7-8cf2-d21aa35d2205@quicinc.com>
From: Suzuki K Poulose <suzuki.poulose@arm.com>
In-Reply-To: <b5965008-b51d-4bb7-8cf2-d21aa35d2205@quicinc.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit

On 19/12/2023 02:13, Tao Zhang wrote:
> 
> On 12/18/2023 6:27 PM, Suzuki K Poulose wrote:
>> On 21/11/2023 02:24, Tao Zhang wrote:
>>> Read the CMB element size from the device tree. Set the register
>>> bit that controls the CMB element size of the corresponding port.
>>>
>>> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
>>> Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com>
>>> ---
>>>   drivers/hwtracing/coresight/coresight-tpda.c | 117 +++++++++++--------
>>>   drivers/hwtracing/coresight/coresight-tpda.h |   6 +
>>>   2 files changed, 74 insertions(+), 49 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-tpda.c 
>>> b/drivers/hwtracing/coresight/coresight-tpda.c
>>> index 5f82737c37bb..e3762f38abb3 100644
>>> --- a/drivers/hwtracing/coresight/coresight-tpda.c
>>> +++ b/drivers/hwtracing/coresight/coresight-tpda.c
>>> @@ -28,24 +28,54 @@ static bool coresight_device_is_tpdm(struct 
>>> coresight_device *csdev)
>>>               CORESIGHT_DEV_SUBTYPE_SOURCE_TPDM);
>>>   }
>>>   +static void tpdm_clear_element_size(struct coresight_device *csdev)
>>> +{
>>> +    struct tpda_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>>> +
>>> +    if (drvdata->dsb_esize)
>>> +        drvdata->dsb_esize = 0;
>>> +    if (drvdata->cmb_esize)
>>> +        drvdata->cmb_esize = 0;
>>
>> Why do we need the if (...) check here ?
> 
> The element size of all the TPDM sub-unit should be set to 0 here.
> 
> I will update this in the next patch series.
> 
>>
>>> +}
>>> +
>>> +static void tpda_set_element_size(struct tpda_drvdata *drvdata, u32 
>>> *val)
>>> +{
>>> +
>>> +    if (drvdata->dsb_esize == 64)
>>> +        *val |= TPDA_Pn_CR_DSBSIZE;
>>> +    else if (drvdata->dsb_esize == 32)
>>> +        *val &= ~TPDA_Pn_CR_DSBSIZE;
>>> +
>>> +    if (drvdata->cmb_esize == 64)
>>> +        *val |= FIELD_PREP(TPDA_Pn_CR_CMBSIZE, 0x2);
>>> +    else if (drvdata->cmb_esize == 32)
>>> +        *val |= FIELD_PREP(TPDA_Pn_CR_CMBSIZE, 0x1);
>>> +    else if (drvdata->cmb_esize == 8)
>>> +        *val &= ~TPDA_Pn_CR_CMBSIZE;
>>> +}
>>> +
>>
>>
>>>   /*
>>> - * Read the DSB element size from the TPDM device
>>> + * Read the element size from the TPDM device
>>>    * Returns
>>> - *    The dsb element size read from the devicetree if available.
>>> + *    The element size read from the devicetree if available.
>>>    *    0 - Otherwise, with a warning once.
>>
>> This doesn't match the function ? It return 0 on success and
>> error (-EINVAL) on failure ?
> 
> 0 means the element size property is found from the devicetree.
> 
> Otherwise, it will return error(-EINVAL).
> 
> I will update this in the next patch series.
> 
>>
>>>    */
>>> -static int tpdm_read_dsb_element_size(struct coresight_device *csdev)
>>> +static int tpdm_read_element_size(struct tpda_drvdata *drvdata,
>>> +                  struct coresight_device *csdev)
>>>   {
>>> -    int rc = 0;
>>> -    u8 size = 0;
>>> -
>>> -    rc = fwnode_property_read_u8(dev_fwnode(csdev->dev.parent),
>>> -            "qcom,dsb-element-size", &size);
>>> +    int rc = -EINVAL;
>>> +
>>> +    if (!fwnode_property_read_u8(dev_fwnode(csdev->dev.parent),
>>> +            "qcom,dsb-element-size", &drvdata->dsb_esize))
>>> +        rc = 0;
>>> +    if (!fwnode_property_read_u8(dev_fwnode(csdev->dev.parent),
>>> +            "qcom,cmb-element-size", &drvdata->cmb_esize))
>>> +        rc = 0;
>>
>> Are we not silently resetting the error if the former failed ?
>>
>> Could we not :
>>
>>     rc |= fwnode_...
>>
>>     rc |= fwnode_...
>>
>> instead ?
>>
>> Also what is the expectation here ? Are these properties a MUST for
>> TPDM ?
> 
> The TPDM must have one of the element size property. As long as one

Please add a comment in the function. Someone else might try to "fix"
it otherwise.

Suzuki
> 
> can be found, this TPDM configuration can be considered valid. So this
> 
> function will return 0 if one of the element size property is found.


> 
> 
> Best,
> 
> Tao
> 
>>
>>>       if (rc)
>>>           dev_warn_once(&csdev->dev,
>>> -            "Failed to read TPDM DSB Element size: %d\n", rc);
>>> +            "Failed to read TPDM Element size: %d\n", rc);
>>>   -    return size;
>>> +    return rc;
>>>   }
>>>     /*
>>> @@ -56,11 +86,12 @@ static int tpdm_read_dsb_element_size(struct 
>>> coresight_device *csdev)
>>>    * Parameter "inport" is used to pass in the input port number
>>>    * of TPDA, and it is set to -1 in the recursize call.
>>>    */
>>> -static int tpda_get_element_size(struct coresight_device *csdev,
>>> +static int tpda_get_element_size(struct tpda_drvdata *drvdata,
>>> +                 struct coresight_device *csdev,
>>>                    int inport)
>>>   {
>>> -    int dsb_size = -ENOENT;
>>> -    int i, size;
>>> +    int rc = 0;
>>> +    int i;
>>>       struct coresight_device *in;
>>>         for (i = 0; i < csdev->pdata->nr_inconns; i++) {
>>> @@ -74,25 +105,21 @@ static int tpda_get_element_size(struct 
>>> coresight_device *csdev,
>>>               continue;
>>>             if (coresight_device_is_tpdm(in)) {
>>> -            size = tpdm_read_dsb_element_size(in);
>>> +            if ((drvdata->dsb_esize) || (drvdata->cmb_esize))
>>> +                return -EEXIST;
>>> +            rc = tpdm_read_element_size(drvdata, in);
>>> +            if (rc)
>>> +                return rc;
>>>           } else {
>>>               /* Recurse down the path */
>>> -            size = tpda_get_element_size(in, -1);
>>> -        }
>>> -
>>> -        if (size < 0)
>>> -            return size;
>>> -
>>> -        if (dsb_size < 0) {
>>> -            /* Found a size, save it. */
>>> -            dsb_size = size;
>>> -        } else {
>>> -            /* Found duplicate TPDMs */
>>> -            return -EEXIST;
>>> +            rc = tpda_get_element_size(drvdata, in, -1);
>>> +            if (rc)
>>> +                return rc;
>>>           }
>>>       }
>>>   -    return dsb_size;
>>> +
>>> +    return rc;
>>>   }
>>>     /* Settings pre enabling port control register */
>>> @@ -109,7 +136,7 @@ static void tpda_enable_pre_port(struct 
>>> tpda_drvdata *drvdata)
>>>   static int tpda_enable_port(struct tpda_drvdata *drvdata, int port)
>>>   {
>>>       u32 val;
>>> -    int size;
>>> +    int rc;
>>>         val = readl_relaxed(drvdata->base + TPDA_Pn_CR(port));
>>>       /*
>>> @@ -117,29 +144,21 @@ static int tpda_enable_port(struct tpda_drvdata 
>>> *drvdata, int port)
>>>        * Set the bit to 0 if the size is 32
>>>        * Set the bit to 1 if the size is 64
>>>        */
>>> -    size = tpda_get_element_size(drvdata->csdev, port);
>>> -    switch (size) {
>>> -    case 32:
>>> -        val &= ~TPDA_Pn_CR_DSBSIZE;
>>> -        break;
>>> -    case 64:
>>> -        val |= TPDA_Pn_CR_DSBSIZE;
>>> -        break;
>>> -    case 0:
>>> -        return -EEXIST;
>>> -    case -EEXIST:
>>> +    tpdm_clear_element_size(drvdata->csdev);
>>> +    rc = tpda_get_element_size(drvdata, drvdata->csdev, port);
>>> +    if (!rc && ((drvdata->dsb_esize) || (drvdata->cmb_esize))) {
>>> +        tpda_set_element_size(drvdata, &val);
>>> +        /* Enable the port */
>>> +        val |= TPDA_Pn_CR_ENA;
>>> +        writel_relaxed(val, drvdata->base + TPDA_Pn_CR(port));
>>> +    } else if (rc == -EEXIST)
>>>           dev_warn_once(&drvdata->csdev->dev,
>>> -            "Detected multiple TPDMs on port %d", -EEXIST);
>>> -        return -EEXIST;
>>> -    default:
>>> -        return -EINVAL;
>>> -    }
>>> -
>>> -    /* Enable the port */
>>> -    val |= TPDA_Pn_CR_ENA;
>>> -    writel_relaxed(val, drvdata->base + TPDA_Pn_CR(port));
>>> +                  "Detected multiple TPDMs on port %d", -EEXIST);
>>> +    else
>>> +        dev_warn_once(&drvdata->csdev->dev,
>>> +                  "Didn't find TPDM elem size");
>>
>> "element size"
>>
>>>   -    return 0;
>>> +    return rc;
>>>   }
>>>     static int __tpda_enable(struct tpda_drvdata *drvdata, int port)
>>> diff --git a/drivers/hwtracing/coresight/coresight-tpda.h 
>>> b/drivers/hwtracing/coresight/coresight-tpda.h
>>> index b3b38fd41b64..29164fd9711f 100644
>>> --- a/drivers/hwtracing/coresight/coresight-tpda.h
>>> +++ b/drivers/hwtracing/coresight/coresight-tpda.h
>>> @@ -10,6 +10,8 @@
>>>   #define TPDA_Pn_CR(n)        (0x004 + (n * 4))
>>>   /* Aggregator port enable bit */
>>>   #define TPDA_Pn_CR_ENA        BIT(0)
>>> +/* Aggregator port CMB data set element size bit */
>>> +#define TPDA_Pn_CR_CMBSIZE        GENMASK(7, 6)
>>>   /* Aggregator port DSB data set element size bit */
>>>   #define TPDA_Pn_CR_DSBSIZE        BIT(8)
>>>   @@ -25,6 +27,8 @@
>>>    * @csdev:      component vitals needed by the framework.
>>>    * @spinlock:   lock for the drvdata value.
>>>    * @enable:     enable status of the component.
>>> + * @dsb_esize   Record the DSB element size.
>>> + * @cmb_esize   Record the CMB element size.
>>>    */
>>>   struct tpda_drvdata {
>>>       void __iomem        *base;
>>> @@ -32,6 +36,8 @@ struct tpda_drvdata {
>>>       struct coresight_device    *csdev;
>>>       spinlock_t        spinlock;
>>>       u8            atid;
>>> +    u8            dsb_esize;
>>> +    u8            cmb_esize;
>>>   };
>>>     #endif  /* _CORESIGHT_CORESIGHT_TPDA_H */
>>
>> Suzuki
>>
>>