diff mbox series

[v5,3/5] dt-bindings: clk: qcom: Add bindings for CPU clock for msm8996

Message ID 1593766185-16346-4-git-send-email-loic.poulain@linaro.org (mailing list archive)
State Superseded
Headers show
Series msm8996 CPU scaling support | expand

Commit Message

Loic Poulain July 3, 2020, 8:49 a.m. UTC 
From: Ilia Lin <ilialin@codeaurora.org>

Each of the CPU clusters (Power and Perf) on msm8996 are
clocked via 2 PLLs, a primary and alternate. There are also
2 Mux'es, a primary and secondary all connected together
as shown below

                             +-------+
              XO             |       |
          +------------------>0      |
                             |       |
                   PLL/2     | SMUX  +----+
                     +------->1      |    |
                     |       |       |    |
                     |       +-------+    |    +-------+
                     |                    +---->0      |
                     |                         |       |
+---------------+    |             +----------->1      | CPU clk
|Primary PLL    +----+ PLL_EARLY   |           |       +------>
|               +------+-----------+    +------>2 PMUX |
+---------------+      |                |      |       |
                       |   +------+     |   +-->3      |
                       +--^+  ACD +-----+   |  +-------+
+---------------+          +------+         |
|Alt PLL        |                           |
|               +---------------------------+
+---------------+         PLL_EARLY

The primary PLL is what drives the CPU clk, except for times
when we are reprogramming the PLL itself (for rate changes) when
we temporarily switch to an alternate PLL. A subsequent patch adds
support to switch between primary and alternate PLL during rate
changes.

The primary PLL operates on a single VCO range, between 600MHz
and 3GHz. However the CPUs do support OPPs with frequencies
between 300MHz and 600MHz. In order to support running the CPUs
at those frequencies we end up having to lock the PLL at twice
the rate and drive the CPU clk via the PLL/2 output and SMUX.

Signed-off-by: Ilia Lin <ilialin@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../bindings/clock/qcom,msm8996-apcc.yaml          | 56 ++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/qcom,msm8996-apcc.yaml

Comments

Stephen Boyd July 11, 2020, 12:13 a.m. UTC | #1 
Quoting Loic Poulain (2020-07-03 01:49:43)
> From: Ilia Lin <ilialin@codeaurora.org>
> 
> Each of the CPU clusters (Power and Perf) on msm8996 are
> clocked via 2 PLLs, a primary and alternate. There are also
> 2 Mux'es, a primary and secondary all connected together
> as shown below
> 
>                              +-------+
>               XO             |       |
>           +------------------>0      |
>                              |       |
>                    PLL/2     | SMUX  +----+
>                      +------->1      |    |
>                      |       |       |    |
>                      |       +-------+    |    +-------+
>                      |                    +---->0      |
>                      |                         |       |
> +---------------+    |             +----------->1      | CPU clk
> |Primary PLL    +----+ PLL_EARLY   |           |       +------>
> |               +------+-----------+    +------>2 PMUX |
> +---------------+      |                |      |       |
>                        |   +------+     |   +-->3      |
>                        +--^+  ACD +-----+   |  +-------+
> +---------------+          +------+         |
> |Alt PLL        |                           |
> |               +---------------------------+
> +---------------+         PLL_EARLY
> 
> The primary PLL is what drives the CPU clk, except for times
> when we are reprogramming the PLL itself (for rate changes) when
> we temporarily switch to an alternate PLL. A subsequent patch adds
> support to switch between primary and alternate PLL during rate
> changes.
> 
> The primary PLL operates on a single VCO range, between 600MHz
> and 3GHz. However the CPUs do support OPPs with frequencies
> between 300MHz and 600MHz. In order to support running the CPUs
> at those frequencies we end up having to lock the PLL at twice
> the rate and drive the CPU clk via the PLL/2 output and SMUX.
> 
> Signed-off-by: Ilia Lin <ilialin@codeaurora.org>
> Reviewed-by: Rob Herring <robh@kernel.org>
> ---

Applied to clk-next
Rob Herring July 13, 2020, 3:21 p.m. UTC | #2 
On Fri, Jul 10, 2020 at 05:13:24PM -0700, Stephen Boyd wrote:
> Quoting Loic Poulain (2020-07-03 01:49:43)
> > From: Ilia Lin <ilialin@codeaurora.org>
> > 
> > Each of the CPU clusters (Power and Perf) on msm8996 are
> > clocked via 2 PLLs, a primary and alternate. There are also
> > 2 Mux'es, a primary and secondary all connected together
> > as shown below
> > 
> >                              +-------+
> >               XO             |       |
> >           +------------------>0      |
> >                              |       |
> >                    PLL/2     | SMUX  +----+
> >                      +------->1      |    |
> >                      |       |       |    |
> >                      |       +-------+    |    +-------+
> >                      |                    +---->0      |
> >                      |                         |       |
> > +---------------+    |             +----------->1      | CPU clk
> > |Primary PLL    +----+ PLL_EARLY   |           |       +------>
> > |               +------+-----------+    +------>2 PMUX |
> > +---------------+      |                |      |       |
> >                        |   +------+     |   +-->3      |
> >                        +--^+  ACD +-----+   |  +-------+
> > +---------------+          +------+         |
> > |Alt PLL        |                           |
> > |               +---------------------------+
> > +---------------+         PLL_EARLY
> > 
> > The primary PLL is what drives the CPU clk, except for times
> > when we are reprogramming the PLL itself (for rate changes) when
> > we temporarily switch to an alternate PLL. A subsequent patch adds
> > support to switch between primary and alternate PLL during rate
> > changes.
> > 
> > The primary PLL operates on a single VCO range, between 600MHz
> > and 3GHz. However the CPUs do support OPPs with frequencies
> > between 300MHz and 600MHz. In order to support running the CPUs
> > at those frequencies we end up having to lock the PLL at twice
> > the rate and drive the CPU clk via the PLL/2 output and SMUX.
> > 
> > Signed-off-by: Ilia Lin <ilialin@codeaurora.org>
> > Reviewed-by: Rob Herring <robh@kernel.org>
> > ---
> 
> Applied to clk-next

And this breaks linux-next:

https://gitlab.com/robherring/linux-dt-bindings/-/jobs/635720095
Stephen Boyd July 16, 2020, 12:53 a.m. UTC | #3 
Quoting Rob Herring (2020-07-13 08:21:10)
> On Fri, Jul 10, 2020 at 05:13:24PM -0700, Stephen Boyd wrote:
> > Quoting Loic Poulain (2020-07-03 01:49:43)
> > > From: Ilia Lin <ilialin@codeaurora.org>
> > > 
> > > Each of the CPU clusters (Power and Perf) on msm8996 are
> > > clocked via 2 PLLs, a primary and alternate. There are also
> > > 2 Mux'es, a primary and secondary all connected together
> > > as shown below
> > > 
> > >                              +-------+
> > >               XO             |       |
> > >           +------------------>0      |
> > >                              |       |
> > >                    PLL/2     | SMUX  +----+
> > >                      +------->1      |    |
> > >                      |       |       |    |
> > >                      |       +-------+    |    +-------+
> > >                      |                    +---->0      |
> > >                      |                         |       |
> > > +---------------+    |             +----------->1      | CPU clk
> > > |Primary PLL    +----+ PLL_EARLY   |           |       +------>
> > > |               +------+-----------+    +------>2 PMUX |
> > > +---------------+      |                |      |       |
> > >                        |   +------+     |   +-->3      |
> > >                        +--^+  ACD +-----+   |  +-------+
> > > +---------------+          +------+         |
> > > |Alt PLL        |                           |
> > > |               +---------------------------+
> > > +---------------+         PLL_EARLY
> > > 
> > > The primary PLL is what drives the CPU clk, except for times
> > > when we are reprogramming the PLL itself (for rate changes) when
> > > we temporarily switch to an alternate PLL. A subsequent patch adds
> > > support to switch between primary and alternate PLL during rate
> > > changes.
> > > 
> > > The primary PLL operates on a single VCO range, between 600MHz
> > > and 3GHz. However the CPUs do support OPPs with frequencies
> > > between 300MHz and 600MHz. In order to support running the CPUs
> > > at those frequencies we end up having to lock the PLL at twice
> > > the rate and drive the CPU clk via the PLL/2 output and SMUX.
> > > 
> > > Signed-off-by: Ilia Lin <ilialin@codeaurora.org>
> > > Reviewed-by: Rob Herring <robh@kernel.org>
> > > ---
> > 
> > Applied to clk-next
> 
> And this breaks linux-next:
> 
> https://gitlab.com/robherring/linux-dt-bindings/-/jobs/635720095

I guess this is the downside of reviewed-by tags going stale.
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/clock/qcom,msm8996-apcc.yaml b/Documentation/devicetree/bindings/clock/qcom,msm8996-apcc.yaml
new file mode 100644
index 0000000..d673ede
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/qcom,msm8996-apcc.yaml
@@ -0,0 +1,56 @@ 
+# SPDX-License-Identifier: GPL-2.0-only
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/qcom,kryocc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm clock controller for MSM8996 CPUs
+
+maintainers:
+  - Loic Poulain <loic.poulain@linaro.org>
+
+description: |
+  Qualcomm CPU clock controller for MSM8996 CPUs, clock 0 is for Power cluster
+  and clock 1 is for Perf cluster.
+
+properties:
+  compatible:
+    enum:
+      - qcom,msm8996-apcc
+
+  reg:
+    maxItems: 1
+
+  '#clock-cells':
+    const: 1
+
+  clocks:
+    items:
+      - description: Primary PLL clock for power cluster (little)
+      - description: Primary PLL clock for perf cluster (big)
+      - description: Alternate PLL clock for power cluster (little)
+      - description: Alternate PLL clock for perf cluster (big)
+
+  clock-names:
+    items:
+      - const: pwrcl_pll
+      - const: perfcl_pll
+      - const: pwrcl_alt_pll
+      - const: perfcl_alt_pll
+
+required:
+  - compatible
+  - reg
+  - '#clock-cells'
+
+additionalProperties: false
+
+examples:
+  # Example for msm8996
+  - |
+    kryocc: clock-controller@6400000 {
+        compatible = "qcom,msm8996-apcc";
+        reg = <0x6400000 0x90000>;
+        #clock-cells = <1>;
+  };
+...