[PATCH v5 04/12] coresight: etm4x: exclude ss_status from drvdata->config

[Mike Leach]

Hi,

On 4/21/26 11:30, Yeoreum Yun wrote:
>> Hi Mike,
>>
>>> Hi,
>>>
>>> This register [bit 31] indicates if a single shot comparator has matched. So
>>> read-back provides information to the user post run to determine which if
>>> any of the comparators set in this way has actually matched.
>>
>> Okay. so after disable sysfs session, to check former session
>> check whether comprator has matched.
>>
>>>
>>> Moreover, the specification states "Software must reset this bit to 0 to
>>> re-enable single-shot control" and "Reset state is unknown. STATUS must be
>>> written to set an initial state...."
>>>
>>> Therefore this register must be written as part of any configuration so
>>> should be available in the drvdata->config for both read and write,
>>
>> But I don't think this is the reason for locate ss_status into "config"
>> since its write purpose is not to configure but the "clear" former bit.
>> That's why I think it's enough to clear when the new sysfs session starts.
>>
> 
> IOW, I think it's better to remove ss_status from configfs item
> and
>    - add field ss_cmp in etm4_cpas
>    - add another field ss_status under "etm4_drvdata" to show "PENDING
>      and STATUS" bits to sysfs after finishing session.
> 
> Is is valid for you?
> 

No. Why two different locations for a single register read? If I have 
the ETMv4 hardware manual I am going to look for a something that is 
recognizable as being related to the single shot comparator status 
register(s).

So in sysfs I would expect to see all the bits from the register, 
displayed, without masking off the STATUS and PENDING bits as happens now.

In the code I would expect to see a single location with a sensible name 
- ss_cmp doesn't really correlate terribly well with TRCSSCSR. If you do 
not like the original ss_status, then ss_cmp_status may actually be 
better, ss_cmp could be either the ss comparator status or control 
register.

Regards

Mike


>> --
>> Sincerely,
>> Yeoreum Yun
>>
> 
> --
> Sincerely,
> Yeoreum Yun