[PATCH 00/17] coresight: next v4.12-rc4

On Mon, 12 Jun 2017 10:50:43 -0600
Mathieu Poirier [off-list ref] wrote:

Hi Mathieu,

On 9 June 2017 at 16:53, Kim Phillips [off-list ref] wrote:

quoted

On Mon,  5 Jun 2017 14:15:01 -0600
Mathieu Poirier [off-list ref] wrote:

Hi Mathieu,

quoted

Please consider for inclusion in the 4.13 cycle.  Of particular interest

is

quoted

patch 15/17, which adds a new driver under the CoreSight umbrella.

After applying the patchseries, the devices now have self-named
subdirectories under them:

$ find /sys/devices/ -name \*sink\*
/sys/devices/platform/20140000.etf/20140000.etf/enable_sink
/sys/devices/platform/20070000.etr/20070000.etr/enable_sink
/sys/devices/platform/20030000.tpiu/20030000.tpiu/enable_sink
/sys/devices/platform/20010000.etf/20010000.etf/enable_sink
$

This is the expected behaviour.  CoreSight devices are found on the AMBA
bus and like other AMBA devices they will show up under
/sys/devices/platform/.

right, but there are subdevices of themselves, e.g.,
20010000.etf/20010000.etf:

kim at juno platform$ find /sys/devices/ -name \*etf\*
/sys/devices/platform/20140000.etf
/sys/devices/platform/20140000.etf/20140000.etf    <- THIS
/sys/devices/platform/20010000.etf
/sys/devices/platform/20010000.etf/20010000.etf    <- and this
/sys/devices/virtual/misc/20140000.etf
/sys/devices/virtual/misc/20010000.etf

'tree' output:

??? 20010000.etf
??? ??? 20010000.etf
??? ??? ??? enable_sink
??? ??? ??? mgmt
??? ??? ??? ??? ctl
??? ??? ??? ??? devid
??? ??? ??? ??? ffcr
??? ??? ??? ??? ffsr
??? ??? ??? ??? mode
??? ??? ??? ??? pscr
??? ??? ??? ??? rrp
??? ??? ??? ??? rsz
??? ??? ??? ??? rwp
??? ??? ??? ??? sts
??? ??? ??? ??? trg
??? ??? ??? power
??? ??? ??? ??? autosuspend_delay_ms
??? ??? ??? ??? control
??? ??? ??? ??? runtime_active_time
??? ??? ??? ??? runtime_status
??? ??? ??? ??? runtime_suspended_time
??? ??? ??? subsystem -> ../../../../bus/coresight
??? ??? ??? trigger_cntr
??? ??? ??? uevent
??? ??? driver -> ../../../bus/amba/drivers/coresight-tmc
??? ??? driver_override
??? ??? id
??? ??? of_node -> ../../../firmware/devicetree/base/etf at 20010000
??? ??? power
??? ??? ??? autosuspend_delay_ms
??? ??? ??? control
??? ??? ??? runtime_active_time
??? ??? ??? runtime_status
??? ??? ??? runtime_suspended_time
??? ??? resource
??? ??? subsystem -> ../../../bus/amba
??? ??? uevent

so things like power/ are duplicated, driver pointers missing from the
sub-node, etc.  I tried reading the documentation to find the reasoning
behind it, and didn't see any, but I may have missed it.  Normally each
platform device gets its own single node, and doesn't create a node
under itself with the same name.

If the subsystem pointer is of use, then I would have
thought 'bus/coresight' would have registered itself as a 'bus/amba'
node? 

quoted

Which doesn't match the coresight.txt usage documentation...

When operating CoreSight from the sysFS interface there is nothing
preventing people from using the entries under /sys/devices/platform should
they wish to.  It is simply easier to use /sys/bus/coresight/devices/, and
that is well documented in coresight.txt.

quoted

Also, do the current juno platforms not have CPU debug modules?  I'd
like to test the new driver.

By all means - Leo pointed out the patch adding the CPU debug entries in
the DT  file for Juno.

Thanks, I applied it, was able to
toggle /sys/kernel/debug/coresight_cpu_debug/enable, but wasn't sure
how to trigger the cpu debug output...

Thanks,

Kim