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authorMike Tipton <quic_mdtipton@quicinc.com>2023-08-07 07:29:14 -0700
committerGeorgi Djakov <djakov@kernel.org>2023-08-22 21:04:50 +0300
commit770c69f037c18cfaa37c3d6c6ef8bd257635513f (patch)
tree488802bd957b41301c9a4b192f518bba2d382aca /Documentation/driver-api
parent1d13d3b745377f49090882e0482e8786e719a6a4 (diff)
interconnect: Add debugfs test client
It's often useful during test, debug, and development to issue path votes from shell. Add a debugfs client for this purpose. Example usage: cd /sys/kernel/debug/interconnect/test-client/ # Configure node endpoints for the path from CPU to DDR on # qcom/sm8550. echo chm_apps > src_node echo ebi > dst_node # Get path between src_node and dst_node. This is only # necessary after updating the node endpoints. echo 1 > get # Set desired BW to 1GBps avg and 2GBps peak. echo 1000000 > avg_bw echo 2000000 > peak_bw # Vote for avg_bw and peak_bw on the latest path from "get". # Voting for multiple paths is possible by repeating this # process for different nodes endpoints. echo 1 > commit Allowing userspace to directly enable and set bus rates can be dangerous So, following in the footsteps of the regmap [0] and clk [1] frameworks, keep these userspace controls compile-time disabled without Kconfig options to enable them. Enabling this will require code changes to define INTERCONNECT_ALLOW_WRITE_DEBUGFS. [0] commit 09c6ecd39410 ("regmap: Add support for writing to regmap registers via debugfs") [1] commit 37215da5553e ("clk: Add support for setting clk_rate via debugfs") Signed-off-by: Mike Tipton <quic_mdtipton@quicinc.com> Link: https://lore.kernel.org/r/20230807142914.12480-4-quic_mdtipton@quicinc.com Signed-off-by: Georgi Djakov <djakov@kernel.org>
Diffstat (limited to 'Documentation/driver-api')
-rw-r--r--Documentation/driver-api/interconnect.rst25
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/driver-api/interconnect.rst b/Documentation/driver-api/interconnect.rst
index 5ed4f57a6bac..a92d0f277a1f 100644
--- a/Documentation/driver-api/interconnect.rst
+++ b/Documentation/driver-api/interconnect.rst
@@ -113,3 +113,28 @@ through dot to generate diagrams in many graphical formats::
$ cat /sys/kernel/debug/interconnect/interconnect_graph | \
dot -Tsvg > interconnect_graph.svg
+
+The ``test-client`` directory provides interfaces for issuing BW requests to
+any arbitrary path. Note that for safety reasons, this feature is disabled by
+default without a Kconfig to enable it. Enabling it requires code changes to
+``#define INTERCONNECT_ALLOW_WRITE_DEBUGFS``. Example usage::
+
+ cd /sys/kernel/debug/interconnect/test-client/
+
+ # Configure node endpoints for the path from CPU to DDR on
+ # qcom/sm8550.
+ echo chm_apps > src_node
+ echo ebi > dst_node
+
+ # Get path between src_node and dst_node. This is only
+ # necessary after updating the node endpoints.
+ echo 1 > get
+
+ # Set desired BW to 1GBps avg and 2GBps peak.
+ echo 1000000 > avg_bw
+ echo 2000000 > peak_bw
+
+ # Vote for avg_bw and peak_bw on the latest path from "get".
+ # Voting for multiple paths is possible by repeating this
+ # process for different nodes endpoints.
+ echo 1 > commit