diff mbox series

[v3,4/4] MIPS: CI20: Add second percpu timer for SMP.

Message ID 1624547189-61079-5-git-send-email-zhouyanjie@wanyeetech.com (mailing list archive)
State Superseded
Headers show
Series Misc Ingenic patches. | expand

Commit Message

Zhou Yanjie June 24, 2021, 3:06 p.m. UTC
1.Add a new TCU channel as the percpu timer of core1, this is to
  prepare for the subsequent SMP support. The newly added channel
  will not adversely affect the current single-core state.
2.Adjust the position of TCU node to make it consistent with the
  order in jz4780.dtsi file.

Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
---

Notes:
    v2:
    New patch.
    
    v2->v3:
    No change.

 arch/mips/boot/dts/ingenic/ci20.dts | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

Comments

Paul Cercueil June 25, 2021, 11:31 a.m. UTC | #1
Hi Zhou,

Le jeu., juin 24 2021 at 23:06:29 +0800, 周琰杰 (Zhou Yanjie) 
<zhouyanjie@wanyeetech.com> a écrit :
> 1.Add a new TCU channel as the percpu timer of core1, this is to
>   prepare for the subsequent SMP support. The newly added channel
>   will not adversely affect the current single-core state.
> 2.Adjust the position of TCU node to make it consistent with the
>   order in jz4780.dtsi file.

That's a bit superfluous, the order matters when adding new nodes, but 
once they are added, moving them around only cause annoyance.

> 
> Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
> ---
> 
> Notes:
>     v2:
>     New patch.
> 
>     v2->v3:
>     No change.
> 
>  arch/mips/boot/dts/ingenic/ci20.dts | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/mips/boot/dts/ingenic/ci20.dts 
> b/arch/mips/boot/dts/ingenic/ci20.dts
> index 8877c62..70005cc 100644
> --- a/arch/mips/boot/dts/ingenic/ci20.dts
> +++ b/arch/mips/boot/dts/ingenic/ci20.dts
> @@ -118,6 +118,17 @@
>  	assigned-clock-rates = <48000000>;
>  };
> 
> +&tcu {
> +	/*
> +	 * 750 kHz for the system timers and 3 MHz for the clocksources,
> +	 * use channel #0 and #1 for the per cpu system timers, and use
> +	 * channel #2 for the clocksource.
> +	 */
> +	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu TCU_CLK_TIMER1>,
> +					  <&tcu TCU_CLK_TIMER2>, <&tcu TCU_CLK_OST>;
> +	assigned-clock-rates = <750000>, <750000>, <3000000>, <3000000>;

Ideally you'd set TIMER1 to 3 MHz and TIMER2 to 750 kHz, otherwise it 
kind of breaks support for older kernels (they would still boot, but 
with a very slow clocksource). So in the new DTS you could use the 
timer0 clock for CPU #0, timer1 for the clocksource, and timer2+ for 
cpus > 0.

Cheers,
-Paul

> +};
> +
>  &mmc0 {
>  	status = "okay";
> 
> @@ -522,13 +533,3 @@
>  		bias-disable;
>  	};
>  };
> -
> -&tcu {
> -	/*
> -	 * 750 kHz for the system timer and 3 MHz for the clocksource,
> -	 * use channel #0 for the system timer, #1 for the clocksource.
> -	 */
> -	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu TCU_CLK_TIMER1>,
> -					  <&tcu TCU_CLK_OST>;
> -	assigned-clock-rates = <750000>, <3000000>, <3000000>;
> -};
> --
> 2.7.4
>
Zhou Yanjie June 25, 2021, 12:14 p.m. UTC | #2
于 Fri, 25 Jun 2021 12:31:17 +0100
Paul Cercueil <paul@crapouillou.net> 写道:

> Hi Zhou,
> 
> Le jeu., juin 24 2021 at 23:06:29 +0800, 周琰杰 (Zhou Yanjie) 
> <zhouyanjie@wanyeetech.com> a écrit :
> > 1.Add a new TCU channel as the percpu timer of core1, this is to
> >   prepare for the subsequent SMP support. The newly added channel
> >   will not adversely affect the current single-core state.
> > 2.Adjust the position of TCU node to make it consistent with the
> >   order in jz4780.dtsi file.  
> 
> That's a bit superfluous, the order matters when adding new nodes,
> but once they are added, moving them around only cause annoyance.
> 
> > 
> > Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
> > ---
> > 
> > Notes:
> >     v2:
> >     New patch.
> > 
> >     v2->v3:
> >     No change.
> > 
> >  arch/mips/boot/dts/ingenic/ci20.dts | 21 +++++++++++----------
> >  1 file changed, 11 insertions(+), 10 deletions(-)
> > 
> > diff --git a/arch/mips/boot/dts/ingenic/ci20.dts 
> > b/arch/mips/boot/dts/ingenic/ci20.dts
> > index 8877c62..70005cc 100644
> > --- a/arch/mips/boot/dts/ingenic/ci20.dts
> > +++ b/arch/mips/boot/dts/ingenic/ci20.dts
> > @@ -118,6 +118,17 @@
> >  	assigned-clock-rates = <48000000>;
> >  };
> > 
> > +&tcu {
> > +	/*
> > +	 * 750 kHz for the system timers and 3 MHz for the
> > clocksources,
> > +	 * use channel #0 and #1 for the per cpu system timers,
> > and use
> > +	 * channel #2 for the clocksource.
> > +	 */
> > +	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu
> > TCU_CLK_TIMER1>,
> > +					  <&tcu TCU_CLK_TIMER2>,
> > <&tcu TCU_CLK_OST>;
> > +	assigned-clock-rates = <750000>, <750000>, <3000000>,
> > <3000000>;  
> 
> Ideally you'd set TIMER1 to 3 MHz and TIMER2 to 750 kHz, otherwise it 
> kind of breaks support for older kernels (they would still boot, but 
> with a very slow clocksource). So in the new DTS you could use the 
> timer0 clock for CPU #0, timer1 for the clocksource, and timer2+ for 
> cpus > 0.

Sure, I will change it in v4.

Thanks and best regards!

> 
> Cheers,
> -Paul
> 
> > +};
> > +
> >  &mmc0 {
> >  	status = "okay";
> > 
> > @@ -522,13 +533,3 @@
> >  		bias-disable;
> >  	};
> >  };
> > -
> > -&tcu {
> > -	/*
> > -	 * 750 kHz for the system timer and 3 MHz for the
> > clocksource,
> > -	 * use channel #0 for the system timer, #1 for the
> > clocksource.
> > -	 */
> > -	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu
> > TCU_CLK_TIMER1>,
> > -					  <&tcu TCU_CLK_OST>;
> > -	assigned-clock-rates = <750000>, <3000000>, <3000000>;
> > -};
> > --
> > 2.7.4
> >   
>
Zhou Yanjie June 25, 2021, 3:19 p.m. UTC | #3
Hi Paul,

于 Fri, 25 Jun 2021 12:31:17 +0100
Paul Cercueil <paul@crapouillou.net> 写道:

> Hi Zhou,
> 
> Le jeu., juin 24 2021 at 23:06:29 +0800, 周琰杰 (Zhou Yanjie) 
> <zhouyanjie@wanyeetech.com> a écrit :
> > 1.Add a new TCU channel as the percpu timer of core1, this is to
> >   prepare for the subsequent SMP support. The newly added channel
> >   will not adversely affect the current single-core state.
> > 2.Adjust the position of TCU node to make it consistent with the
> >   order in jz4780.dtsi file.  
> 
> That's a bit superfluous, the order matters when adding new nodes,
> but once they are added, moving them around only cause annoyance.
> 
> > 
> > Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
> > ---
> > 
> > Notes:
> >     v2:
> >     New patch.
> > 
> >     v2->v3:
> >     No change.
> > 
> >  arch/mips/boot/dts/ingenic/ci20.dts | 21 +++++++++++----------
> >  1 file changed, 11 insertions(+), 10 deletions(-)
> > 
> > diff --git a/arch/mips/boot/dts/ingenic/ci20.dts 
> > b/arch/mips/boot/dts/ingenic/ci20.dts
> > index 8877c62..70005cc 100644
> > --- a/arch/mips/boot/dts/ingenic/ci20.dts
> > +++ b/arch/mips/boot/dts/ingenic/ci20.dts
> > @@ -118,6 +118,17 @@
> >  	assigned-clock-rates = <48000000>;
> >  };
> > 
> > +&tcu {
> > +	/*
> > +	 * 750 kHz for the system timers and 3 MHz for the
> > clocksources,
> > +	 * use channel #0 and #1 for the per cpu system timers,
> > and use
> > +	 * channel #2 for the clocksource.
> > +	 */
> > +	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu
> > TCU_CLK_TIMER1>,
> > +					  <&tcu TCU_CLK_TIMER2>,
> > <&tcu TCU_CLK_OST>;
> > +	assigned-clock-rates = <750000>, <750000>, <3000000>,
> > <3000000>;  
> 
> Ideally you'd set TIMER1 to 3 MHz and TIMER2 to 750 kHz, otherwise it 
> kind of breaks support for older kernels (they would still boot, but 
> with a very slow clocksource). So in the new DTS you could use the 
> timer0 clock for CPU #0, timer1 for the clocksource, and timer2+ for 
> cpus > 0.

I checked the ingenic-timer driver, and it seems that the last TCU
channel is always used as the clocksource in the driver, so it seems
that we can only use timer2 as the clocksource in smp mode. Maybe we
should add a note for smp is closed in the comment. And I found that I
missed a problem, Nikolaus Schaller once reported that because the
frequency of the tcu timer (only 16bit) used to provide the clocksource
is too high, there will be a chance that the system will get stuck
before the clocksource is switched to ost. And reducing the clocksource
to 750kz can prevent it from happening. I will add this part to v4.
When this part is added, both clockevent and clocksource will be
750kHz, but the 750kHz clocksource is only temporary, because it will
then switch to the clocksource provided by ost, and ost works at 3MHz.

Thanks and best regards!

> 
> Cheers,
> -Paul
> 
> > +};
> > +
> >  &mmc0 {
> >  	status = "okay";
> > 
> > @@ -522,13 +533,3 @@
> >  		bias-disable;
> >  	};
> >  };
> > -
> > -&tcu {
> > -	/*
> > -	 * 750 kHz for the system timer and 3 MHz for the
> > clocksource,
> > -	 * use channel #0 for the system timer, #1 for the
> > clocksource.
> > -	 */
> > -	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu
> > TCU_CLK_TIMER1>,
> > -					  <&tcu TCU_CLK_OST>;
> > -	assigned-clock-rates = <750000>, <3000000>, <3000000>;
> > -};
> > --
> > 2.7.4
> >   
>
Paul Cercueil June 25, 2021, 3:47 p.m. UTC | #4
Hi Zhou,

Le ven., juin 25 2021 at 23:19:42 +0800, 周琰杰 
<zhouyanjie@wanyeetech.com> a écrit :
> Hi Paul,
> 
> 于 Fri, 25 Jun 2021 12:31:17 +0100
> Paul Cercueil <paul@crapouillou.net> 写道:
> 
>>  Hi Zhou,
>> 
>>  Le jeu., juin 24 2021 at 23:06:29 +0800, 周琰杰 (Zhou Yanjie)
>>  <zhouyanjie@wanyeetech.com> a écrit :
>>  > 1.Add a new TCU channel as the percpu timer of core1, this is to
>>  >   prepare for the subsequent SMP support. The newly added channel
>>  >   will not adversely affect the current single-core state.
>>  > 2.Adjust the position of TCU node to make it consistent with the
>>  >   order in jz4780.dtsi file.
>> 
>>  That's a bit superfluous, the order matters when adding new nodes,
>>  but once they are added, moving them around only cause annoyance.
>> 
>>  >
>>  > Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
>>  > ---
>>  >
>>  > Notes:
>>  >     v2:
>>  >     New patch.
>>  >
>>  >     v2->v3:
>>  >     No change.
>>  >
>>  >  arch/mips/boot/dts/ingenic/ci20.dts | 21 +++++++++++----------
>>  >  1 file changed, 11 insertions(+), 10 deletions(-)
>>  >
>>  > diff --git a/arch/mips/boot/dts/ingenic/ci20.dts
>>  > b/arch/mips/boot/dts/ingenic/ci20.dts
>>  > index 8877c62..70005cc 100644
>>  > --- a/arch/mips/boot/dts/ingenic/ci20.dts
>>  > +++ b/arch/mips/boot/dts/ingenic/ci20.dts
>>  > @@ -118,6 +118,17 @@
>>  >  	assigned-clock-rates = <48000000>;
>>  >  };
>>  >
>>  > +&tcu {
>>  > +	/*
>>  > +	 * 750 kHz for the system timers and 3 MHz for the
>>  > clocksources,
>>  > +	 * use channel #0 and #1 for the per cpu system timers,
>>  > and use
>>  > +	 * channel #2 for the clocksource.
>>  > +	 */
>>  > +	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu
>>  > TCU_CLK_TIMER1>,
>>  > +					  <&tcu TCU_CLK_TIMER2>,
>>  > <&tcu TCU_CLK_OST>;
>>  > +	assigned-clock-rates = <750000>, <750000>, <3000000>,
>>  > <3000000>;
>> 
>>  Ideally you'd set TIMER1 to 3 MHz and TIMER2 to 750 kHz, otherwise 
>> it
>>  kind of breaks support for older kernels (they would still boot, but
>>  with a very slow clocksource). So in the new DTS you could use the
>>  timer0 clock for CPU #0, timer1 for the clocksource, and timer2+ for
>>  cpus > 0.
> 
> I checked the ingenic-timer driver, and it seems that the last TCU
> channel is always used as the clocksource in the driver, so it seems
> that we can only use timer2 as the clocksource in smp mode. Maybe we
> should add a note for smp is closed in the comment. And I found that I
> missed a problem, Nikolaus Schaller once reported that because the
> frequency of the tcu timer (only 16bit) used to provide the 
> clocksource
> is too high, there will be a chance that the system will get stuck
> before the clocksource is switched to ost. And reducing the 
> clocksource
> to 750kz can prevent it from happening. I will add this part to v4.
> When this part is added, both clockevent and clocksource will be
> 750kHz, but the 750kHz clocksource is only temporary, because it will
> then switch to the clocksource provided by ost, and ost works at 3MHz.

Ok, then first change the clocksource to 750 kHz, then update it with 
timer2.

Cheers,
-Paul

> 
> Thanks and best regards!
> 
>> 
>>  Cheers,
>>  -Paul
>> 
>>  > +};
>>  > +
>>  >  &mmc0 {
>>  >  	status = "okay";
>>  >
>>  > @@ -522,13 +533,3 @@
>>  >  		bias-disable;
>>  >  	};
>>  >  };
>>  > -
>>  > -&tcu {
>>  > -	/*
>>  > -	 * 750 kHz for the system timer and 3 MHz for the
>>  > clocksource,
>>  > -	 * use channel #0 for the system timer, #1 for the
>>  > clocksource.
>>  > -	 */
>>  > -	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu
>>  > TCU_CLK_TIMER1>,
>>  > -					  <&tcu TCU_CLK_OST>;
>>  > -	assigned-clock-rates = <750000>, <3000000>, <3000000>;
>>  > -};
>>  > --
>>  > 2.7.4
>>  >
>> 
>
Zhou Yanjie June 25, 2021, 4:32 p.m. UTC | #5
Hi Paul,

于 Fri, 25 Jun 2021 16:47:30 +0100
Paul Cercueil <paul@crapouillou.net> 写道:

> Hi Zhou,
> 
> Le ven., juin 25 2021 at 23:19:42 +0800, 周琰杰 
> <zhouyanjie@wanyeetech.com> a écrit :
> > Hi Paul,
> > 
> > 于 Fri, 25 Jun 2021 12:31:17 +0100
> > Paul Cercueil <paul@crapouillou.net> 写道:
> >   
> >>  Hi Zhou,
> >> 
> >>  Le jeu., juin 24 2021 at 23:06:29 +0800, 周琰杰 (Zhou Yanjie)
> >>  <zhouyanjie@wanyeetech.com> a écrit :  
> >>  > 1.Add a new TCU channel as the percpu timer of core1, this is to
> >>  >   prepare for the subsequent SMP support. The newly added
> >>  > channel will not adversely affect the current single-core state.
> >>  > 2.Adjust the position of TCU node to make it consistent with the
> >>  >   order in jz4780.dtsi file.  
> >> 
> >>  That's a bit superfluous, the order matters when adding new nodes,
> >>  but once they are added, moving them around only cause annoyance.
> >>   
> >>  >
> >>  > Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
> >>  > ---
> >>  >
> >>  > Notes:
> >>  >     v2:
> >>  >     New patch.
> >>  >
> >>  >     v2->v3:
> >>  >     No change.
> >>  >
> >>  >  arch/mips/boot/dts/ingenic/ci20.dts | 21 +++++++++++----------
> >>  >  1 file changed, 11 insertions(+), 10 deletions(-)
> >>  >
> >>  > diff --git a/arch/mips/boot/dts/ingenic/ci20.dts
> >>  > b/arch/mips/boot/dts/ingenic/ci20.dts
> >>  > index 8877c62..70005cc 100644
> >>  > --- a/arch/mips/boot/dts/ingenic/ci20.dts
> >>  > +++ b/arch/mips/boot/dts/ingenic/ci20.dts
> >>  > @@ -118,6 +118,17 @@
> >>  >  	assigned-clock-rates = <48000000>;
> >>  >  };
> >>  >
> >>  > +&tcu {
> >>  > +	/*
> >>  > +	 * 750 kHz for the system timers and 3 MHz for the
> >>  > clocksources,
> >>  > +	 * use channel #0 and #1 for the per cpu system timers,
> >>  > and use
> >>  > +	 * channel #2 for the clocksource.
> >>  > +	 */
> >>  > +	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu  
> >>  > TCU_CLK_TIMER1>,  
> >>  > +					  <&tcu
> >>  > TCU_CLK_TIMER2>, <&tcu TCU_CLK_OST>;
> >>  > +	assigned-clock-rates = <750000>, <750000>, <3000000>,
> >>  > <3000000>;  
> >> 
> >>  Ideally you'd set TIMER1 to 3 MHz and TIMER2 to 750 kHz,
> >> otherwise it
> >>  kind of breaks support for older kernels (they would still boot,
> >> but with a very slow clocksource). So in the new DTS you could use
> >> the timer0 clock for CPU #0, timer1 for the clocksource, and
> >> timer2+ for cpus > 0.  
> > 
> > I checked the ingenic-timer driver, and it seems that the last TCU
> > channel is always used as the clocksource in the driver, so it seems
> > that we can only use timer2 as the clocksource in smp mode. Maybe we
> > should add a note for smp is closed in the comment. And I found
> > that I missed a problem, Nikolaus Schaller once reported that
> > because the frequency of the tcu timer (only 16bit) used to provide
> > the clocksource
> > is too high, there will be a chance that the system will get stuck
> > before the clocksource is switched to ost. And reducing the 
> > clocksource
> > to 750kz can prevent it from happening. I will add this part to v4.
> > When this part is added, both clockevent and clocksource will be
> > 750kHz, but the 750kHz clocksource is only temporary, because it
> > will then switch to the clocksource provided by ost, and ost works
> > at 3MHz.  
> 
> Ok, then first change the clocksource to 750 kHz, then update it with 
> timer2.

Sure, I will do it in v4.

Thanks and best regards!

> 
> Cheers,
> -Paul
> 
> > 
> > Thanks and best regards!
> >   
> >> 
> >>  Cheers,
> >>  -Paul
> >>   
> >>  > +};
> >>  > +
> >>  >  &mmc0 {
> >>  >  	status = "okay";
> >>  >
> >>  > @@ -522,13 +533,3 @@
> >>  >  		bias-disable;
> >>  >  	};
> >>  >  };
> >>  > -
> >>  > -&tcu {
> >>  > -	/*
> >>  > -	 * 750 kHz for the system timer and 3 MHz for the
> >>  > clocksource,
> >>  > -	 * use channel #0 for the system timer, #1 for the
> >>  > clocksource.
> >>  > -	 */
> >>  > -	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu  
> >>  > TCU_CLK_TIMER1>,  
> >>  > -					  <&tcu TCU_CLK_OST>;
> >>  > -	assigned-clock-rates = <750000>, <3000000>, <3000000>;
> >>  > -};
> >>  > --
> >>  > 2.7.4
> >>  >  
> >>   
> >   
>
diff mbox series

Patch

diff --git a/arch/mips/boot/dts/ingenic/ci20.dts b/arch/mips/boot/dts/ingenic/ci20.dts
index 8877c62..70005cc 100644
--- a/arch/mips/boot/dts/ingenic/ci20.dts
+++ b/arch/mips/boot/dts/ingenic/ci20.dts
@@ -118,6 +118,17 @@ 
 	assigned-clock-rates = <48000000>;
 };
 
+&tcu {
+	/*
+	 * 750 kHz for the system timers and 3 MHz for the clocksources,
+	 * use channel #0 and #1 for the per cpu system timers, and use
+	 * channel #2 for the clocksource.
+	 */
+	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu TCU_CLK_TIMER1>,
+					  <&tcu TCU_CLK_TIMER2>, <&tcu TCU_CLK_OST>;
+	assigned-clock-rates = <750000>, <750000>, <3000000>, <3000000>;
+};
+
 &mmc0 {
 	status = "okay";
 
@@ -522,13 +533,3 @@ 
 		bias-disable;
 	};
 };
-
-&tcu {
-	/*
-	 * 750 kHz for the system timer and 3 MHz for the clocksource,
-	 * use channel #0 for the system timer, #1 for the clocksource.
-	 */
-	assigned-clocks = <&tcu TCU_CLK_TIMER0>, <&tcu TCU_CLK_TIMER1>,
-					  <&tcu TCU_CLK_OST>;
-	assigned-clock-rates = <750000>, <3000000>, <3000000>;
-};