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Message-ID: <ef2d485f-1a43-46b1-ba71-12623332e7bf@quicinc.com>
Date: Mon, 15 Jan 2024 14:20:11 +0800
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Subject: Re: [PATCH v3 8/8] coresight-tpdm: Add msr register support for CMB
Content-Language: en-US
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>,
        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>
 <1700533494-19276-9-git-send-email-quic_taozha@quicinc.com>
 <185b23e7-a42f-4a12-85ba-8a093bc5ea58@arm.com>
 <4409f3cf-7ca9-407f-92c0-5aa7ba6f7b61@quicinc.com>
 <d8262a32-cc3c-4889-a5f0-a6b128b7e9d6@arm.com>
 <3e27b0e2-afb2-4706-9996-f567e33e35ba@quicinc.com>
 <94f504c4-76dd-4139-a8e0-c2858b7937bb@quicinc.com>
 <bfc274b8-8b60-4d7d-a8bf-467bc8ebbf1c@arm.com>
From: Tao Zhang <quic_taozha@quicinc.com>
In-Reply-To: <bfc274b8-8b60-4d7d-a8bf-467bc8ebbf1c@arm.com>
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On 1/12/2024 5:43 PM, Suzuki K Poulose wrote:
> On 12/01/2024 09:12, Tao Zhang wrote:
>>
>> On 12/20/2023 5:06 PM, Tao Zhang wrote:
>>>
>>> On 12/19/2023 10:09 PM, Suzuki K Poulose wrote:
>>>> On 19/12/2023 06:58, Tao Zhang wrote:
>>>>>
>>>>> On 12/18/2023 7:02 PM, Suzuki K Poulose wrote:
>>>>>> On 21/11/2023 02:24, Tao Zhang wrote:
>>>>>>> Add the nodes for CMB subunit MSR(mux select register) support.
>>>>>>> CMB MSRs(mux select registers) is to separate mux,arbitration,
>>>>>>> ,interleaving,data packing control from stream filtering control.
>>>>>>>
>>>>>>> Reviewed-by: James Clark <james.clark@arm.com>
>>>>>>> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
>>>>>>> Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com>
>>>>>>> ---
>>>>>>>   .../testing/sysfs-bus-coresight-devices-tpdm  |  8 ++
>>>>>>>   drivers/hwtracing/coresight/coresight-tpdm.c  | 86 
>>>>>>> +++++++++++++++++++
>>>>>>>   drivers/hwtracing/coresight/coresight-tpdm.h  | 16 +++-
>>>>>>>   3 files changed, 109 insertions(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git 
>>>>>>> a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm 
>>>>>>> b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>>>>>>> index e0b77107be13..914f3fd81525 100644
>>>>>>> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>>>>>>> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
>>>>>>> @@ -249,3 +249,11 @@ Description:
>>>>>>>           Accepts only one of the 2 values -  0 or 1.
>>>>>>>           0 : Disable the timestamp of all trace packets.
>>>>>>>           1 : Enable the timestamp of all trace packets.
>>>>>>> +
>>>>>>> +What: /sys/bus/coresight/devices/<tpdm-name>/cmb_msr/msr[0:31]
>>>>>>> +Date:        September 2023
>>>>>>> +KernelVersion    6.7
>>>>>>> +Contact:    Jinlong Mao (QUIC) <quic_jinlmao@quicinc.com>, Tao 
>>>>>>> Zhang (QUIC) <quic_taozha@quicinc.com>
>>>>>>> +Description:
>>>>>>> +        (RW) Set/Get the MSR(mux select register) for the CMB 
>>>>>>> subunit
>>>>>>> +        TPDM.
>>>>>>> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c 
>>>>>>> b/drivers/hwtracing/coresight/coresight-tpdm.c
>>>>>>> index f6cda5616e84..7e331ea436cc 100644
>>>>>>> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
>>>>>>> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
>>>>>>> @@ -86,6 +86,11 @@ static ssize_t 
>>>>>>> tpdm_simple_dataset_show(struct device *dev,
>>>>>>>               return -EINVAL;
>>>>>>>           return sysfs_emit(buf, "0x%x\n",
>>>>>>> drvdata->cmb->patt_mask[tpdm_attr->idx]);
>>>>>>> +    case CMB_MSR:
>>>>>>> +        if (tpdm_attr->idx >= drvdata->cmb_msr_num)
>>>>>>> +            return -EINVAL;
>>>>>>> +        return sysfs_emit(buf, "0x%x\n",
>>>>>>> + drvdata->cmb->msr[tpdm_attr->idx]);
>>>>>>>       }
>>>>>>>       return -EINVAL;
>>>>>>>   }
>>>>>>> @@ -162,6 +167,12 @@ static ssize_t 
>>>>>>> tpdm_simple_dataset_store(struct device *dev,
>>>>>>>           else
>>>>>>>               ret = -EINVAL;
>>>>>>>           break;
>>>>>>> +    case CMB_MSR:
>>>>>>> +        if (tpdm_attr->idx < drvdata->cmb_msr_num)
>>>>>>> + drvdata->cmb->msr[tpdm_attr->idx] = val;
>>>>>>> +        else
>>>>>>> +            ret = -EINVAL;
>>>>>>
>>>>>>
>>>>>> minor nit: Could we not break from here instead of adding return 
>>>>>> -EINVAL
>>>>>> for each case ? (I understand it has been done for the existing 
>>>>>> cases.
>>>>>> But I think we should clean up all of that, including the ones 
>>>>>> you added
>>>>>> in Patch 5. Similarly for the dataset_show()
>>>>>
>>>>> Sure, do I also need to change the DSB corresponding code? If so, 
>>>>> how about
>>>>>
>>>>> if I add a new patch to the next patch series to change the 
>>>>> previous existing cases?
>>>>
>>>> You could fix the existing cases as a preparatory patch of the next 
>>>> version of this series. I can pick it up and push it to next as I 
>>>> see fit.
>>>
>>> Got it. I will update this to the next patch series.
>>
>> Hi Suzuki,
>>
>>
>> Since the dataset data is configured with spin lock protection, it 
>> needs to be unlock before return.
>>
>> List my modification below. Would you mind help review to see if it 
>> is good for you.
>>
>> static ssize_t tpdm_simple_dataset_store(struct device *dev,
>>                       struct device_attribute *attr,
>>                       const char *buf,
>>                       size_t size)
>> {
>>      unsigned long val;
>>
>>      struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
>>      struct tpdm_dataset_attribute *tpdm_attr =
>>          container_of(attr, struct tpdm_dataset_attribute, attr);
>>
>>      if (kstrtoul(buf, 0, &val))
>>          return -EINVAL;
>>
>>      spin_lock(&drvdata->spinlock);
>
> Use guard() to avoid explicit unlock on return and then you don't need 
> the spin_unlock() everywhere. It would be done on return from the
> function implicitly.
>
>
>>      switch (tpdm_attr->mem) {
>>      case DSB_TRIG_PATT:
>
> With guard() in place:
>
>     ret = -EINVAL;
>
>     switch () {
>     case XXX:
>
>        if (tpdm_attr->idx < TPDM_XXXX_IDX) {
>            drvdata->dsb->trig_patt[tpdm_attr->idx] = val;
>            ret = size;
>        }
>        break;
>     case ...
>         ...
>     }
>
>     return ret;

Thanks for your suggestion. I will update the code like below.

I will update it in the next version of the patch series if it meets 
your expectation.

static ssize_t tpdm_simple_dataset_store(struct device *dev,
                      struct device_attribute *attr,
                      const char *buf,
                      size_t size)
{
     unsigned long val;
     ssize_t ret = -EINVAL;

     struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
     struct tpdm_dataset_attribute *tpdm_attr =
         container_of(attr, struct tpdm_dataset_attribute, attr);

     if (kstrtoul(buf, 0, &val))
         return ret;

     guard(spinlock)(&drvdata->spinlock);
     switch (tpdm_attr->mem) {
     case DSB_TRIG_PATT:
         if (tpdm_attr->idx < TPDM_DSB_MAX_PATT) {
             drvdata->dsb->trig_patt[tpdm_attr->idx] = val;
             ret =size;
         }
         break;
     case ...

         ...
     }
     return ret;
}

Best,

Tao

>
>
> Suzuki
>