Re: [PATCH v2 4/9] of: Add bindings of hw throttle for soctherm

[Eduardo Valentin <edubezval-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Thu, Apr 28, 2016 at 02:48:41PM +0800, Wei Ni wrote:
> 
> 
> On 2016年04月28日 07:30, Eduardo Valentin wrote:
> > From: Eduardo Valentin <edubezval-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > To: Wei Ni <wni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> > Cc: thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, rui.zhang@intel.com,
> > 	MLongnecker-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org,
> > 	mikko.perttunen-/1wQRMveznE@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
> > 	linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
> > 	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> > Bcc: 
> > Subject: Re: [PATCH v2 4/9] of: Add bindings of hw throttle for soctherm
> > Reply-To: 
> > In-Reply-To: <1461727554-15065-5-git-send-email-wni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> > 
> > The patch title must say something about the fact that this is specific
> > to nvidia thermal driver.
> 
> Yes, it's my mistake, will fix it in next series.
> 
> > 
> > On Wed, Apr 27, 2016 at 11:25:49AM +0800, Wei Ni wrote:
> >> Add HW throttle configuration sub-node for soctherm, which
> >> is used to describe the throttle event, and worked as a
> >> cooling device. The "hot" type trip in thermal zone can
> >> be bound to this cooling device, and trigger the throttle
> >> function.
> >>
> >> Signed-off-by: Wei Ni <wni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> >> ---
> >>  .../bindings/thermal/nvidia,tegra124-soctherm.txt  | 89 +++++++++++++++++++++-
> >>  1 file changed, 87 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt b/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt
> >> index edebfa0a985e..dc337d139f49 100644
> >> --- a/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt
> >> +++ b/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt
> >> @@ -10,8 +10,14 @@ Required properties :
> >>  - compatible : For Tegra124, must contain "nvidia,tegra124-soctherm".
> >>    For Tegra132, must contain "nvidia,tegra132-soctherm".
> >>    For Tegra210, must contain "nvidia,tegra210-soctherm".
> >> -- reg : Should contain 1 entry:
> >> +- reg : Should contain at least 2 entries for each entry in reg-names:
> >>    - SOCTHERM register set
> >> +  - Tegra CAR register set: Required for Tegra124 and Tegra210.
> >> +  - CCROC register set: Required for Tegra132.
> >> +- reg-names :  Should contain at least 2 entries:
> >> +  - soctherm-reg
> >> +  - car-reg
> >> +  - ccroc-reg
> >>  - interrupts : Defines the interrupt used by SOCTHERM
> >>  - clocks : Must contain an entry for each entry in clock-names.
> >>    See ../clocks/clock-bindings.txt for details.
> >> @@ -25,17 +31,44 @@ Required properties :
> >>  - #thermal-sensor-cells : Should be 1. See ./thermal.txt for a description
> >>      of this property. See <dt-bindings/thermal/tegra124-soctherm.h> for a
> >>      list of valid values when referring to thermal sensors.
> >> +- throttle-cfgs: A sub-node which is a container of configuration for each
> >> +    hardware throttle events. These events can be set as cooling devices.
> >> +  * throttle events: Sub-nodes must be named as "light" or "heavy".
> >> +      Properties:
> >> +      - priority: Each throttles has its own throttle settings, so the SW need
> >> +        to set priorities for various throttle, the HW arbiter can select the
> >> +        final throttle settings.
> >> +        Bigger value indicates higher priority, In general, higher priority
> >> +        translates to lower target frequency. SW needs to ensure that critical
> >> +        thermal alarms are given higher priority, and ensure that there is
> >> +        no race if priority of two vectors is set to the same value.
> >> +      - cpu-throt-depth:  This property is for Tegra124 and Tegra210. It is
> >> +        the throttling depth of pulse skippers, it's the percentage
> >> +        throttling.
> >> +      - cpu-throt-level: This property is only for Tegra132, it is the level
> >> +        of pulse skippers, which used to throttle clock frequencies. It
> >> +        indicates cpu clock throttling depth, and the depth can be programmed.
> >> +        Must set as following values:
> >> +        TEGRA_SOCTHERM_THROT_LEVEL_LOW, TEGRA_SOCTHERM_THROT_LEVEL_MED
> >> +        TEGRA_SOCTHERM_THROT_LEVEL_HIGH, TEGRA_SOCTHERM_THROT_LEVEL_NONE
> > 
> > These properties are not generic properties. My understanding is that
> > you must have vendor prefix in such case. Same applies to the new nodes.
> 
> Ok, will do it.
> 
> > 
> >> +      - #cooling-cells: Should be 1. This cooling device only support on/off state.
> >> +        See ./thermal.txt for a description of this property.
> >>  
> >>  Note:
> >>  - the "critical" type trip points will be set to SOC_THERM hardware as the
> >>  shut down temperature. Once the temperature of this thermal zone is higher
> >>  than it, the system will be shutdown or reset by hardware.
> >> +- the "hot" type trip points will be set to SOC_THERM hardware as the throttle
> >> +temperature. Once the the temperature of this thermal zone is higher
> >> +than it, it will trigger the HW throttle event.
> >>  
> >>  Example :
> >>  
> >>  	soctherm@700e2000 {
> >>  		compatible = "nvidia,tegra124-soctherm";
> >> -		reg = <0x0 0x700e2000 0x0 0x1000>;
> >> +		reg = <0x0 0x700e2000 0x0 0x600  /* SOC_THERM reg_base */
> >> +			0x0 0x60006000 0x0 0x400 /* CAR reg_base */
> >> +		reg-names = "soctherm-reg", "car-reg";
> >>  		interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
> >>  		clocks = <&tegra_car TEGRA124_CLK_TSENSOR>,
> >>  			<&tegra_car TEGRA124_CLK_SOC_THERM>;
> >> @@ -44,6 +77,45 @@ Example :
> >>  		reset-names = "soctherm";
> >>  
> >>  		#thermal-sensor-cells = <1>;
> >> +
> >> +		throttle-cfgs {
> >> +			throttle_heavy: heavy {
> >> +				priority = <100>;
> >> +				cpu-throt-depth = <85>;
> >> +
> >> +				#cooling-cells = <1>;
> >> +			};
> >> +			throttle_light: light {
> >> +				priority = <80>;
> >> +				cpu-throt-depth = <50>;
> >> +
> >> +				#cooling-cells = <1>;
> >> +			};
> >> +		};
> > 
> > This is a sensor, which at the same time, has sub nodes that can be
> > cooling devices. Is my understanding correct of what you are trying to
> > do?
> 
> Yes, we set this sub nodes as cooling devices.
> Let me explain it.
> The Tegra's soctherm has the HW throttle function, it will be triggered when the
> temperatures reach to the "hot" type trip. These throttle events can be
> configured to different levels "heavy" and "light" on different sensors. So it
> something like cooling devices which can be bound with thermal zones, and in
> this way, we can use the linux of-thermal framework to handle it. If not, we
> have to add more codes to parse these configuration and set them for those
> sensors. I had used this method to handle the shutdown function in Tegra's
> soctherm driver in my previous series, however Rob didn't like it, he preferred
> to use linux framework to handle it.
> So I think it's better to set these throttle-cfgs as cooling devices, so they
> can be bound to the cpu/gpu thermal zones easily.
> 
> > 
> > 
> >> +	};
> >> +
> >> +Example: referring to Tegra132's "reg", "reg-names" and "throttle-cfgs" :
> >> +
> >> +	soctherm@0,700e2000 {
> >> +		compatible = "nvidia,tegra132-soctherm";
> >> +		reg = <0x0 0x700e2000 0x0 0x600  /* SOC_THERM reg_base */
> >> +			0x0 0x70040000 0x0 0x200>; /* CCROC reg_base */;
> >> +		reg-names = "soctherm-reg", "ccroc-reg";
> >> +
> >> +		throttle-cfgs {
> >> +			throttle_heavy: heavy {
> >> +				priority = <100>;
> >> +				cpu-throt-level = <TEGRA_SOCTHERM_THROT_LEVEL_HIGH>;
> >> +
> >> +				#cooling-cells = <1>;
> >> +			};
> >> +			throttle_light: light {
> >> +				priority = <80>;
> >> +				cpu-throt-level = <TEGRA_SOCTHERM_THROT_LEVEL_MED>;
> >> +
> >> +				#cooling-cells = <1>;
> > 
> > Could you please describe a little here what to expect of the above
> > setup?
> 
> Ok, let me describe it.
> When the "heavy" cooling device triggered, the hardware will skip cpu clock's
> pulse in HIGH level, and if the "light" triggered, the hardware will skip cpu
> clock's pulse in MED level.
> If these two devices are triggered in same time, the HW throttle arbiter will
> select the highest priority as the final throttle settings to skip cpu pulse.


I would prefer if you add these descriptions into your examples in your
next version.

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