Re: [PATCH 3/9] coresight-tpdm: Initialize DSB subunit configuration

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

On 26/10/2022 09:10, Tao Zhang wrote:
> Hi Suzuki,
> 
> 在 10/24/2022 6:02 PM, Suzuki K Poulose 写道:
>> Hi
>>
>> On 08/09/2022 09:44, Tao Zhang wrote:
>>> DSB subunit need to be configured in enablement and disablement.
>>> A struct that specifics associated to dsb dataset is needed. It
>>> saves the configuration and parameters of the dsb datasets. This
>>> change is to add this struct and initialize the configuration of
>>> DSB subunit.
>>>
>>> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
>>> ---
>>>   drivers/hwtracing/coresight/coresight-tpdm.c | 44 
>>> ++++++++++++++++++++++++++--
>>>   drivers/hwtracing/coresight/coresight-tpdm.h | 17 +++++++++++
>>>   2 files changed, 58 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c 
>>> b/drivers/hwtracing/coresight/coresight-tpdm.c
>>> index 88df3e6..69ea453 100644
>>> --- a/drivers/hwtracing/coresight/coresight-tpdm.c
>>> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c
>>> @@ -24,6 +24,22 @@ static void tpdm_enable_dsb(struct tpdm_drvdata 
>>> *drvdata)
>>>   {
>>>       u32 val;
>>>   +    val = readl_relaxed(drvdata->base + TPDM_DSB_TIER);
>>> +    /* Set trigger timestamp */
>>> +    if (drvdata->dsb->trig_ts)
>>
>> What happens if this instance doesn't have a DSB set ? Have
>> you tested this on a system without the DSB ?
>>
> The function "tpdm_enable_dsb" will only be called when it is checked 
> that the DSB dataset is present.
> 
> And only the TPDM that supports the DSB dataset will have the DSB TIER 
> register.
> 
> If the TPDM doesn't support the DSB dataset, this instance should not be 
> run. Otherwise, it will cause that the incorrect register is accessed.

Thanks, this is what happens when you send something that is not queued
anywhwere. Please provide a reference tree in the future, for ease of
reviewing such things

Suzuki