From 9d77db3c730780c8ef5ccd4b66403ff5675cfe4e Mon Sep 17 00:00:00 2001 From: hc <hc@nodka.com> Date: Mon, 13 May 2024 10:30:14 +0000 Subject: [PATCH] modify sin led gpio --- kernel/Documentation/trace/intel_th.rst | 32 ++++++++++++++++++++++++++++++-- 1 files changed, 30 insertions(+), 2 deletions(-) diff --git a/kernel/Documentation/trace/intel_th.rst b/kernel/Documentation/trace/intel_th.rst index 19e2d63..b31818d 100644 --- a/kernel/Documentation/trace/intel_th.rst +++ b/kernel/Documentation/trace/intel_th.rst @@ -1,3 +1,5 @@ +.. SPDX-License-Identifier: GPL-2.0 + ======================= Intel(R) Trace Hub (TH) ======================= @@ -42,7 +44,8 @@ MSU can be configured to collect trace data into a system memory buffer, which can later on be read from its device nodes via read() or -mmap() interface. +mmap() interface and directed to a "software sink" driver that will +consume the data and/or relay it further. On the whole, Intel(R) Trace Hub does not require any special userspace software to function; everything can be configured, started @@ -55,7 +58,7 @@ For each Intel TH device in the system a bus of its own is created and assigned an id number that reflects the order in which TH -devices were emumerated. All TH subdevices (devices on intel_th bus) +devices were enumerated. All TH subdevices (devices on intel_th bus) begin with this id: 0-gth, 0-msc0, 0-msc1, 0-pti, 0-sth, which is followed by device's name and an optional index. @@ -120,3 +123,28 @@ will show up on the intel_th bus. Also, trace configuration and capture controlling attribute groups of the 'gth' device will not be exposed. The 'sth' device will operate as usual. + +Software Sinks +-------------- + +The Memory Storage Unit (MSU) driver provides an in-kernel API for +drivers to register themselves as software sinks for the trace data. +Such drivers can further export the data via other devices, such as +USB device controllers or network cards. + +The API has two main parts:: + - notifying the software sink that a particular window is full, and + "locking" that window, that is, making it unavailable for the trace + collection; when this happens, the MSU driver will automatically + switch to the next window in the buffer if it is unlocked, or stop + the trace capture if it's not; + - tracking the "locked" state of windows and providing a way for the + software sink driver to notify the MSU driver when a window is + unlocked and can be used again to collect trace data. + +An example sink driver, msu-sink illustrates the implementation of a +software sink. Functionally, it simply unlocks windows as soon as they +are full, keeping the MSU running in a circular buffer mode. Unlike the +"multi" mode, it will fill out all the windows in the buffer as opposed +to just the first one. It can be enabled by writing "sink" to the "mode" +file (assuming msu-sink.ko is loaded). -- Gitblit v1.6.2