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

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

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;


Suzuki