Re: [PATCH] coresight: Add coresight name support

[Jinlong Mao]

On 1/3/2024 11:32 PM, Rob Herring wrote:
> On Tue, Jan 2, 2024 at 5:05 AM Mike Leach <mike.leach@xxxxxxxxxx> wrote:
> > As James mentions this is clearly a V2 of a previous patch - please
> > mark as such in future.
> >
> > Adding to what James has already said:-
> >
> > 1) Mapping between the canonical names used in the drivers and the
> > information as to the precise device is as easy as running 'ls' on
> > /sys/bus/coresight/devices:-
> >
> > root@linaro-developer:/home/linaro/cs-mods# ls -al /sys/bus/coresight/devices/
> > total 0
> > drwxr-xr-x 2 root root 0 Jan  2 11:27 .
> > drwxr-xr-x 4 root root 0 Jan  2 11:27 ..
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 cti_cpu0 ->
> > ../../../devices/platform/soc@0/858000.cti/cti_cpu0
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 cti_cpu1 ->
> > ../../../devices/platform/soc@0/859000.cti/cti_cpu1
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 cti_cpu2 ->
> > ../../../devices/platform/soc@0/85a000.cti/cti_cpu2
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 cti_cpu3 ->
> > ../../../devices/platform/soc@0/85b000.cti/cti_cpu3
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 cti_sys0 ->
> > ../../../devices/platform/soc@0/810000.cti/cti_sys0
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 cti_sys1 ->
> > ../../../devices/platform/soc@0/811000.cti/cti_sys1
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 etm0 ->
> > ../../../devices/platform/soc@0/85c000.etm/etm0
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 etm1 ->
> > ../../../devices/platform/soc@0/85d000.etm/etm1
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 etm2 ->
> > ../../../devices/platform/soc@0/85e000.etm/etm2
> > lrwxrwxrwx 1 root root 0 Jan  2 11:27 etm3 ->
> > ../../../devices/platform/soc@0/85f000.etm/etm3
> > lrwxrwxrwx 1 root root 0 Jan  2 11:42 funnel0 ->
> > ../../../devices/platform/soc@0/821000.funnel/funnel0
> > lrwxrwxrwx 1 root root 0 Jan  2 11:42 funnel1 ->
> > ../../../devices/platform/soc@0/841000.funnel/funnel1
> > lrwxrwxrwx 1 root root 0 Jan  2 11:42 replicator0 ->
> > ../../../devices/platform/soc@0/824000.replicator/replicator0
> > lrwxrwxrwx 1 root root 0 Jan  2 11:42 tmc_etf0 ->
> > ../../../devices/platform/soc@0/825000.etf/tmc_etf0
> > lrwxrwxrwx 1 root root 0 Jan  2 11:42 tmc_etr0 ->
> > ../../../devices/platform/soc@0/826000.etr/tmc_etr0
> >
> >
> > 2) The patch set must contain the usage and specification in the .yaml
> >   file(s) of the property used.
>
> For the record, I don't like "coresight-name". I don't have another
> suggestion because "easy" is not sufficient reasoning for why this is
> needed.

For example, if we want to configure the trigger and HW events for 
modem, we can't know which cti or TPDM is for modem from current names.

lrwxrwxrwx    1 root     0                0 Jan  1 00:01 cti_sys0 -> 
./../../devices/platform/soc@0/138f0000.cti/cti_sys0
lrwxrwxrwx    1 root     0                0 Jan  1 00:01 cti_sys1 -> 
./../../devices/platform/soc@0/13900000.cti/cti_sys1
lrwxrwxrwx    1 root     0                0 Jan  1 00:01 tpdm0 -> 
./../../devices/platform/soc@0/10b0d000.tpdm/tpdm0
lrwxrwxrwx    1 root     0                0 Jan  1 00:01 tpdm1 -> 
./../../devices/platform/soc@0/10c28000.tpdm/tpdm1
lrwxrwxrwx    1 root     0                0 Jan  1 00:01 tpdm2 -> 
./../../devices/platform/soc@0/10c29000.tpdm/tpdm2

Thanks
Jinlong Mao
> > However, there was a standard property called 'name' which is
> > deprecated - see
> > https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html
> > section 2.3.11. I do not believe that adding another 'name' property
> > would be accepted by the DT maintainers.
>
> "name" is just the node name for anything in the last 15 years. They
> used to be separate, but would still mostly be the same. The only case
> I found with them different was old PowerPC Macs.
>
> > 3) the 'device_node' structure has a 'name' field that contains the
> > node name in the DT approved "node-name@unit-address" format.
>
> Actually, it is without the unit-address. full_name is with the unit-address.
>
> > This
> > contains whatever node names you used in the dt.  Why not use this if
> > a change has to be made and find some conditional to activate it.
>
> Don't go accessing "name" or "full_name" directly. I intend to get rid
> of "name" and generate it from full_name. So use the accessors and
> printk specifiers if you need node names.
>
> Rob