linux-kernel - [PATCH v7 1/7] dt-bindings: opp: Introduce opp-peak-kBps and opp-avg-kBps bindings

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Date:   Fri, 24 Apr 2020 18:53:58 +0300
From:   Georgi Djakov <georgi.djakov@...aro.org>
To:     vireshk@...nel.org, nm@...com, sboyd@...nel.org,
        robh+dt@...nel.org, rjw@...ysocki.net, saravanak@...gle.com,
        sibis@...eaurora.org
Cc:     rnayak@...eaurora.org, bjorn.andersson@...aro.org,
        vincent.guittot@...aro.org, jcrouse@...eaurora.org,
        evgreen@...omium.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        georgi.djakov@...aro.org
Subject: [PATCH v7 1/7] dt-bindings: opp: Introduce opp-peak-kBps and opp-avg-kBps bindings

From: Saravana Kannan <saravanak@...gle.com>

Interconnects often quantify their performance points in terms of
bandwidth. So, add opp-peak-kBps (required) and opp-avg-kBps (optional) to
allow specifying Bandwidth OPP tables in DT.

opp-peak-kBps is a required property that replaces opp-hz for Bandwidth OPP
tables.

opp-avg-kBps is an optional property that can be used in Bandwidth OPP
tables.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
Signed-off-by: Georgi Djakov <georgi.djakov@...aro.org>
---
v7:
* I have dropped Rob's Reviewed-by, because of the minor change below:
* In order to store the bandwidth values for multiple paths, the
opp-peak-kBps and opp-avg-kBps are now defined as arrays of integers,
instead of just integers.
* Improved wording (Viresh)

v6: https://lore.kernel.org/r/20191207002424.201796-2-saravanak@google.com

 Documentation/devicetree/bindings/opp/opp.txt | 20 ++++++++++++++++---
 .../devicetree/bindings/property-units.txt    |  4 ++++
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
index 68592271461f..a8a6a3bfcfcb 100644
--- a/Documentation/devicetree/bindings/opp/opp.txt
+++ b/Documentation/devicetree/bindings/opp/opp.txt
@@ -83,9 +83,17 @@ properties.
 
 Required properties:
 - opp-hz: Frequency in Hz, expressed as a 64-bit big-endian integer. This is a
-  required property for all device nodes but devices like power domains. The
-  power domain nodes must have another (implementation dependent) property which
-  uniquely identifies the OPP nodes.
+  required property for all device nodes except for devices like power domains
+  or bandwidth opp tables. The devices which don't have this property must have
+  another (implementation dependent) property which uniquely identifies the OPP
+  nodes.
+
+
+- opp-peak-kBps: Peak bandwidth in kilobytes per second, expressed as an array
+  of 32-bit big-endian integers. Each element of the array represents the
+  peak bandwidth value of each interconnect path. The number of elements should
+  match the number of interconnect paths. This is a required property for
+  bandwidth OPP tables.
 
 Optional properties:
 - opp-microvolt: voltage in micro Volts.
@@ -132,6 +140,12 @@ Optional properties:
 - opp-level: A value representing the performance level of the device,
   expressed as a 32-bit integer.
 
+- opp-avg-kBps: Average bandwidth in kilobytes per second, expressed as an array
+  of 32-bit big-endian integers. Each element of the array represents the
+  average bandwidth value of each interconnect path. The number of elements
+  should match the number of interconnect paths. This property is only
+  meaningful in OPP tables where opp-peak-kBps is present.
+
 - clock-latency-ns: Specifies the maximum possible transition latency (in
   nanoseconds) for switching to this OPP from any other OPP.
 
diff --git a/Documentation/devicetree/bindings/property-units.txt b/Documentation/devicetree/bindings/property-units.txt
index e9b8360b3288..c80a110c1e26 100644
--- a/Documentation/devicetree/bindings/property-units.txt
+++ b/Documentation/devicetree/bindings/property-units.txt
@@ -41,3 +41,7 @@ Temperature
 Pressure
 ----------------------------------------
 -kpascal	: kilopascal
+
+Throughput
+----------------------------------------
+-kBps		: kilobytes per second