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

From: Eduardo Valentin
Date: Thu Apr 28 2016 - 10:48:44 EST

On Thu, Apr 28, 2016 at 02:48:41PM +0800, Wei Ni wrote:
>
>
> On 2016å04æ28æ 07:30, Eduardo Valentin wrote:
> > From: Eduardo Valentin <edubezval@xxxxxxxxx>
> > To: Wei Ni <wni@xxxxxxxxxx>
> > Cc: thierry.reding@xxxxxxxxx, robh+dt@xxxxxxxxxx, rui.zhang@xxxxxxxxx,
> > MLongnecker@xxxxxxxxxx, swarren@xxxxxxxxxxxxx,
> > mikko.perttunen@xxxxxxxx, linux-tegra@xxxxxxxxxxxxxxx,
> > linux-pm@xxxxxxxxxxxxxxx, devicetree@xxxxxxxxxxxxxxx,
> > linux-kernel@xxxxxxxxxxxxxxx
> > 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@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxx>
> >> ---
> >> .../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.