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SubjectRe: [PATCH v3] coresight: documentation: update sysfs section
On 14 May 2018 at 13:18, Kim Phillips <kim.phillips@arm.com> wrote:
> - 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@linaro.org>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Signed-off-by: Kim Phillips <kim.phillips@arm.com>

I'm good with this version - Jonathan, should I take this through my
tree of you'll take care of it?

In case of the former:
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>

> ---
> 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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