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Message-ID: <987a101d-043e-4893-89c0-f9fcd46b5aeb@arm.com>
Date: Tue, 19 Dec 2023 13:59:30 +0000
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Subject: Re: [PATCH v3 2/8] coresight-tpda: Add support to configure CMB
 element
Content-Language: en-GB
From: Suzuki K Poulose <suzuki.poulose@arm.com>
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>
In-Reply-To: <88e51407-344e-4584-8711-29cc014c782b@arm.com>
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On 18/12/2023 10:27, 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 ?
> 
>> +}
>> +
>> +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 ?
> 
>>    */
>> -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))

At this point we have the csdev->dev.parent as the TPDM device and with:

#include <coresight-tpdm.h>

	struct tpdm_drvdata *tpdm_data = get_drvdata(csdev->dev.parent);

	if (tpdm_has_cmb(tpdm_data)) {
		rc = fwnode_...(... "qcom,cmb-element-size"...)
	}

	if (tpdm_has_dsb(tpdm_data)) {
		rc = fwnode_...(..., "qcom,dsb-element-size"..)
	}

Suzuki


>> +        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 ?
> 
>>       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
> 
>