- Align and show updated ls devices output from the TC2, based on
current driver
- Provide an example from an ETMv4 based system (Juno)
- Reflect changes to the way the RAM write pointer is accessed since
it got changed in commit 7d83d17795ef ("coresight: tmc: adding sysFS
management entries").
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Signed-off-by: Kim Phillips <kim.phillips@xxxxxxx>
---
v3: address Randy Dunlap's showns->shown, corrected - and + line merging
v2: address Mathieu's comment about clarifying the sinks on the Juno
vs. TC2 platforms.
Documentation/trace/coresight.txt | 43 +++++++++++++++++++------------
1 file changed, 26 insertions(+), 17 deletions(-)
diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt
index 6f0120c3a4f1..15d2a0f1e1b8 100644
--- a/Documentation/trace/coresight.txt
+++ b/Documentation/trace/coresight.txt
@@ -141,13 +141,25 @@ register the device with the core framework. The unregister function takes
a reference to a "struct coresight_device", obtained at registration time.
If everything goes well during the registration process the new devices will
-show up under /sys/bus/coresight/devices, as showns here for a TC2 platform:
+show up under /sys/bus/coresight/devices, as shown here for a TC2 platform:
root:~# ls /sys/bus/coresight/devices/
-replicator 20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm
-20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm
+20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm replicator
+20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm
root:~#
+and here for a Juno platform:
+
+root@juno:~# ls /sys/bus/coresight/devices/
+20010000.etf 20120000.replicator 22040000.etm 230c0000.funnel
+20030000.tpiu 20130000.funnel 220c0000.funnel 23140000.etm
+20040000.funnel 20140000.etf 22140000.etm 23240000.etm
+20070000.etr 20150000.funnel 23040000.etm 23340000.etm
+root@juno:~#
+
+Note that on Juno users can select the ETF, ETR and TPIU as a sink target while
+on TC2, the ETB and TPIU can be selected.
+
The functions take a "struct coresight_device", which looks like this:
struct coresight_desc {
@@ -193,16 +205,16 @@ the information carried in "THIS_MODULE".
How to use the tracer modules
-----------------------------
-Before trace collection can start, a coresight sink needs to be identify.
+Before trace collection can start, a coresight sink needs to be identified.
There is no limit on the amount of sinks (nor sources) that can be enabled at
any given moment. As a generic operation, all device pertaining to the sink
class will have an "active" entry in sysfs:
root:/sys/bus/coresight/devices# ls
-replicator 20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm
-20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm
+20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm replicator
+20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm
root:/sys/bus/coresight/devices# ls 20010000.etb
-enable_sink status trigger_cntr
+enable_sink mgmt power subsystem trigger_cntr uevent
root:/sys/bus/coresight/devices# echo 1 > 20010000.etb/enable_sink
root:/sys/bus/coresight/devices# cat 20010000.etb/enable_sink
1
@@ -216,16 +228,13 @@ trigger a trace capture:
root:/sys/bus/coresight/devices# echo 1 > 2201c000.ptm/enable_source
root:/sys/bus/coresight/devices# cat 2201c000.ptm/enable_source
1
-root:/sys/bus/coresight/devices# cat 20010000.etb/status
-Depth: 0x2000
-Status: 0x1
-RAM read ptr: 0x0
-RAM wrt ptr: 0x19d3 <----- The write pointer is moving
-Trigger cnt: 0x0
-Control: 0x1
-Flush status: 0x0
-Flush ctrl: 0x2001
-root:/sys/bus/coresight/devices#
+
+Observe the write pointer moving:
+
+root:/sys/bus/coresight/devices# cat 20010000.etb/mgmt/rwp
+0x1a8
+root:/sys/bus/coresight/devices# cat 20010000.etb/mgmt/rwp
+0x19a6
Trace collection is stopped the same way:
--
2.17.0
--
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