From b29f6d3e59a1ff8dd5c0aeae8594801a15efcc2c Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Mon, 26 Sep 2016 15:27:05 +0300 Subject: [PATCH] stm class: Document stm_source channel assignment This patch adds an explanation of how and when stm_source devices are assigned STP masters and channels. Signed-off-by: Alexander Shishkin --- Documentation/trace/stm.txt | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/Documentation/trace/stm.txt b/Documentation/trace/stm.txt index 349869851463..11cff47eecce 100644 --- a/Documentation/trace/stm.txt +++ b/Documentation/trace/stm.txt @@ -85,6 +85,16 @@ $ echo dummy_stm.0 > /sys/class/stm_source/console/stm_source_link For examples on how to use stm_source interface in the kernel, refer to stm_console or stm_heartbeat drivers. +Each stm_source device will need to assume a master and a range of +channels, depending on how many channels it requires. These are +allocated for the device according to the policy configuration. If +there's a node in the root of the policy directory that matches the +stm_source device's name (for example, "console"), this node will be +used to allocate master and channel numbers. If there's no such policy +node, the stm core will pick the first contiguous chunk of channels +within the first available master. Note that the node must exist +before the stm_source device is connected to its stm device. + stm_console ===========