Re: [PATCH v3 8/8] coresight-tpdm: Add msr register support for CMB

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 15/01/2024 06:20, Tao Zhang wrote:
> 
> 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;
> }
> 

Yes that looks good to me. Please rebase this on to for-next/queue 
branch on the coresight repository.

Suzuki