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

Message

Dario Binacchi March 29, 2021, 4:42 p.m. UTC

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(-)

Comments

Stephen Boyd March 30, 2021, 2:24 a.m. UTC | #1

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?

Tony Lindgren March 31, 2021, 5:51 a.m. UTC | #2

* Stephen Boyd <[e-mail]> [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

Dario Binacchi March 31, 2021, 4:48 p.m. UTC | #3

> Il 31/03/2021 07:51 Tony Lindgren <[e-mail]> ha scritto:
> 
>  
> * Stephen Boyd <[e-mail]> [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 [e-mail] ?
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

Stephen Boyd April 1, 2021, 1:47 a.m. UTC | #4

Quoting Tony Lindgren (2021-03-30 22:51:04)
> * Stephen Boyd <[e-mail]> [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.

Dario Binacchi May 9, 2021, 1:06 p.m. UTC | #5

Hi Stephen, Hi Tony

> Il 01/04/2021 03:47 Stephen Boyd <[e-mail]> ha scritto:
> 
>  
> Quoting Tony Lindgren (2021-03-30 22:51:04)
> > * Stephen Boyd <[e-mail]> [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