[PATCH v3 0/4] clk: ti: add am33xx spread spectrum clock support

[PATCH v3 0/4] clk: ti: add am33xx spread spectrum clock support

[Dario Binacchi]

As reported by the TI spruh73x RM, MPU and LCD modules support spread
spectrum clocking (SSC) on their output clocks. SSC is used to spread
the spectral peaking of the clock to reduce any electromagnetic
interference (EMI) that may be caused due to the clock’s fundamental
or any of its harmonics.
The series allows you to enable and adjust the spread spectrum clocking
for all am33xx PLLs for which it is supported.


Changes in v3:
- Add '-hz' suffix to "ti,ssc-modfreq" binding.
- Add Tony Lindgren acked tag.
- Use "ti,ssc-modfreq-hz" binding instead of "ti,ssc-modfreq".

Changes in v2:
- Remove SSC registers from dpll_core_ck@490 node (SSC is not supported)
- Add SSC registers to dpll_mpu_ck@488 node.
- Move the DT changes to the previous patch in the series.

Dario Binacchi (4):
  clk: ti: fix typo in routine description
  dt-bindings: ti: dpll: add spread spectrum support
  ARM: dts: am33xx-clocks: add spread spectrum support
  clk: ti: add am33xx spread spectrum clock support

 .../devicetree/bindings/clock/ti/dpll.txt     | 20 +++++
 arch/arm/boot/dts/am33xx-clocks.dtsi          |  4 +-
 drivers/clk/ti/dpll.c                         | 42 +++++++++
 drivers/clk/ti/dpll3xxx.c                     | 87 ++++++++++++++++++-
 include/linux/clk/ti.h                        | 24 +++++
 5 files changed, 174 insertions(+), 3 deletions(-)

-- 
2.17.1

[PATCH v3 2/4] dt-bindings: ti: dpll: add spread spectrum support

[Dario Binacchi]

DT bindings for enabling and adjusting spread spectrum clocking have
been added.

Signed-off-by: Dario Binacchi <dariobin@libero.it>

---

Changes in v3:
- Add '-hz' suffix to "ti,ssc-modfreq" binding.

 .../devicetree/bindings/clock/ti/dpll.txt     | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/devicetree/bindings/clock/ti/dpll.txt b/Documentation/devicetree/bindings/clock/ti/dpll.txt
index df57009ff8e7..37a7cb6ad07d 100644
--- a/Documentation/devicetree/bindings/clock/ti/dpll.txt
+++ b/Documentation/devicetree/bindings/clock/ti/dpll.txt
@@ -42,6 +42,11 @@ Required properties:
 	"idlest" - contains the idle status register base address
 	"mult-div1" - contains the multiplier / divider register base address
 	"autoidle" - contains the autoidle register base address (optional)
+	"ssc-deltam" - DPLL supports spread spectrum clocking (SSC), contains
+		       the frequency spreading register base address (optional)
+	"ssc-modfreq" - DPLL supports spread spectrum clocking (SSC), contains
+		        the modulation frequency register base address
+			(optional)
   ti,am3-* dpll types do not have autoidle register
   ti,omap2-* dpll type does not support idlest / autoidle registers
 
@@ -51,6 +56,14 @@ Optional properties:
 	- ti,low-power-stop : DPLL supports low power stop mode, gating output
 	- ti,low-power-bypass : DPLL output matches rate of parent bypass clock
 	- ti,lock : DPLL locks in programmed rate
+	- ti,min-div : the minimum divisor to start from to round the DPLL
+		       target rate
+	- ti,ssc-deltam : DPLL supports spread spectrum clocking, frequency
+			  spreading in permille (10th of a percent)
+	- ti,ssc-modfreq-hz : DPLL supports spread spectrum clocking, spread
+			      spectrum modulation frequency
+	- ti,ssc-downspread : DPLL supports spread spectrum clocking, boolean
+			      to enable the downspread feature
 
 Examples:
 	dpll_core_ck: dpll_core_ck@44e00490 {
@@ -83,3 +96,10 @@ Examples:
 		clocks = <&sys_ck>, <&sys_ck>;
 		reg = <0x0500>, <0x0540>;
 	};
+
+	dpll_disp_ck: dpll_disp_ck {
+		#clock-cells = <0>;
+		compatible = "ti,am3-dpll-no-gate-clock";
+		clocks = <&sys_clkin_ck>, <&sys_clkin_ck>;
+		reg = <0x0498>, <0x0448>, <0x0454>, <0x044c>, <0x0450>;
+	};
-- 
2.17.1

[PATCH v3 3/4] ARM: dts: am33xx-clocks: add spread spectrum support

[Dario Binacchi]

Registers for adjusting the spread spectrum clocking (SSC) have been
added. As reported by the TI spruh73x RM, SSC is supported only for
LCD and MPU PLLs.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Acked-by: Tony Lindgren <tony@atomide.com>

---

Changes in v3:
- Add Tony Lindgren acked tag.

Changes in v2:
- Remove SSC registers from dpll_core_ck@490 node (SSC is not supported)
- Add SSC registers to dpll_mpu_ck@488 node.

 arch/arm/boot/dts/am33xx-clocks.dtsi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/boot/dts/am33xx-clocks.dtsi b/arch/arm/boot/dts/am33xx-clocks.dtsi
index dced92a8970e..a02e0b1229a4 100644
--- a/arch/arm/boot/dts/am33xx-clocks.dtsi
+++ b/arch/arm/boot/dts/am33xx-clocks.dtsi
@@ -204,7 +204,7 @@
 		#clock-cells = <0>;
 		compatible = "ti,am3-dpll-clock";
 		clocks = <&sys_clkin_ck>, <&sys_clkin_ck>;
-		reg = <0x0488>, <0x0420>, <0x042c>;
+		reg = <0x0488>, <0x0420>, <0x042c>, <0x0424>, <0x0428>;
 	};
 
 	dpll_mpu_m2_ck: dpll_mpu_m2_ck@4a8 {
@@ -244,7 +244,7 @@
 		#clock-cells = <0>;
 		compatible = "ti,am3-dpll-no-gate-clock";
 		clocks = <&sys_clkin_ck>, <&sys_clkin_ck>;
-		reg = <0x0498>, <0x0448>, <0x0454>;
+		reg = <0x0498>, <0x0448>, <0x0454>, <0x044c>, <0x0450>;
 	};
 
 	dpll_disp_m2_ck: dpll_disp_m2_ck@4a4 {
-- 
2.17.1

Re: [PATCH v3 0/4] clk: ti: add am33xx spread spectrum clock support

[Stephen Boyd]

Quoting Dario Binacchi (2021-03-29 09:42:17)
> 
> As reported by the TI spruh73x RM, MPU and LCD modules support spread
> spectrum clocking (SSC) on their output clocks. SSC is used to spread
> the spectral peaking of the clock to reduce any electromagnetic
> interference (EMI) that may be caused due to the clock’s fundamental
> or any of its harmonics.
> The series allows you to enable and adjust the spread spectrum clocking
> for all am33xx PLLs for which it is supported.
> 

What is your merge strategy? Should all the patches go through clk tree?
Or you'll send via arm-soc?

Re: [PATCH v3 2/4] dt-bindings: ti: dpll: add spread spectrum support

[Rob Herring]

On Mon, 29 Mar 2021 18:42:19 +0200, Dario Binacchi wrote:
> DT bindings for enabling and adjusting spread spectrum clocking have
> been added.
> 
> Signed-off-by: Dario Binacchi <dariobin@libero.it>
> 
> ---
> 
> Changes in v3:
> - Add '-hz' suffix to "ti,ssc-modfreq" binding.
> 
>  .../devicetree/bindings/clock/ti/dpll.txt     | 20 +++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v3 0/4] clk: ti: add am33xx spread spectrum clock support

[Tony Lindgren]

* Stephen Boyd <sboyd@kernel.org> [210330 02:25]:
> Quoting Dario Binacchi (2021-03-29 09:42:17)
> > 
> > As reported by the TI spruh73x RM, MPU and LCD modules support spread
> > spectrum clocking (SSC) on their output clocks. SSC is used to spread
> > the spectral peaking of the clock to reduce any electromagnetic
> > interference (EMI) that may be caused due to the clock’s fundamental
> > or any of its harmonics.
> > The series allows you to enable and adjust the spread spectrum clocking
> > for all am33xx PLLs for which it is supported.
> > 
> 
> What is your merge strategy? Should all the patches go through clk tree?
> Or you'll send via arm-soc?

Probably best to just merge all via the clk tree as that's where most of
the changes are.

Regards,

Tony

Re: [PATCH v3 0/4] clk: ti: add am33xx spread spectrum clock support

[Dario Binacchi]

> Il 31/03/2021 07:51 Tony Lindgren <tony@atomide.com> ha scritto:
> 
>  
> * Stephen Boyd <sboyd@kernel.org> [210330 02:25]:
> > Quoting Dario Binacchi (2021-03-29 09:42:17)
> > > 
> > > As reported by the TI spruh73x RM, MPU and LCD modules support spread
> > > spectrum clocking (SSC) on their output clocks. SSC is used to spread
> > > the spectral peaking of the clock to reduce any electromagnetic
> > > interference (EMI) that may be caused due to the clock’s fundamental
> > > or any of its harmonics.
> > > The series allows you to enable and adjust the spread spectrum clocking
> > > for all am33xx PLLs for which it is supported.
> > > 
> > 
> > What is your merge strategy? Should all the patches go through clk tree?
> > Or you'll send via arm-soc?
> 
> Probably best to just merge all via the clk tree as that's where most of
> the changes are.
> 

This means that I no longer have to send patches to TI / OMAP maintainers, commiters 
and fixers, as well as at linux-omap@vger.kernel.org ?
Even if the a1e980789b06 ("am335x-spread-spectrum) clk: ti: add am33xx spread spectrum clock support") 
patch is basically related to the AM33xx/AM43xx SOCs?

Thanks and regards,
Dario

> Regards,
> 
> Tony

Re: [PATCH v3 0/4] clk: ti: add am33xx spread spectrum clock support

[Stephen Boyd]

Quoting Tony Lindgren (2021-03-30 22:51:04)
> * Stephen Boyd <sboyd@kernel.org> [210330 02:25]:
> > Quoting Dario Binacchi (2021-03-29 09:42:17)
> > > 
> > > As reported by the TI spruh73x RM, MPU and LCD modules support spread
> > > spectrum clocking (SSC) on their output clocks. SSC is used to spread
> > > the spectral peaking of the clock to reduce any electromagnetic
> > > interference (EMI) that may be caused due to the clock’s fundamental
> > > or any of its harmonics.
> > > The series allows you to enable and adjust the spread spectrum clocking
> > > for all am33xx PLLs for which it is supported.
> > > 
> > 
> > What is your merge strategy? Should all the patches go through clk tree?
> > Or you'll send via arm-soc?
> 
> Probably best to just merge all via the clk tree as that's where most of
> the changes are.
> 

Ok. If nobody reviews/acks the last patch in a few days I'll merge the
pile through clk tree.

Re: [PATCH v3 0/4] clk: ti: add am33xx spread spectrum clock support

[Dario Binacchi]

Hi Stephen, Hi Tony

> Il 01/04/2021 03:47 Stephen Boyd <sboyd@kernel.org> ha scritto:
> 
>  
> Quoting Tony Lindgren (2021-03-30 22:51:04)
> > * Stephen Boyd <sboyd@kernel.org> [210330 02:25]:
> > > Quoting Dario Binacchi (2021-03-29 09:42:17)
> > > > 
> > > > As reported by the TI spruh73x RM, MPU and LCD modules support spread
> > > > spectrum clocking (SSC) on their output clocks. SSC is used to spread
> > > > the spectral peaking of the clock to reduce any electromagnetic
> > > > interference (EMI) that may be caused due to the clock’s fundamental
> > > > or any of its harmonics.
> > > > The series allows you to enable and adjust the spread spectrum clocking
> > > > for all am33xx PLLs for which it is supported.
> > > > 
> > > 
> > > What is your merge strategy? Should all the patches go through clk tree?
> > > Or you'll send via arm-soc?
> > 
> > Probably best to just merge all via the clk tree as that's where most of
> > the changes are.
> > 
> 
> Ok. If nobody reviews/acks the last patch in a few days I'll merge the
> pile through clk tree.

It's been over a month since I submitted the patches. Meanwhile Tero Kristo has 
reviewed the most important patch of the series. However, I have not seen any 
progress in the state of the series. Furthermore, I don't see the DTS patches 
in the clk tree. Am I missing something? Or do I have to do something? Sorry 
for the questions but I don't have much experience with patch merge strategies.

Thanks and regards,
Dario