On 2020-10-14 18:59, Akhil P Oommen wrote:
On 10/9/2020 10:27 PM, Matthias Kaehlcke wrote:
On Fri, Oct 09, 2020 at 08:05:10AM -0700, Doug Anderson wrote:
Hi,
On Thu, Oct 8, 2020 at 10:10 AM Akhil P Oommen
<akhilpo@xxxxxxxxxxxxxx> wrote:
Add cooling-cells property and the cooling maps for the gpu tzones
to support GPU cooling.
Signed-off-by: Akhil P Oommen <akhilpo@xxxxxxxxxxxxxx>
---
arch/arm64/boot/dts/qcom/sc7180.dtsi | 29
++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/boot/dts/qcom/sc7180.dtsi
b/arch/arm64/boot/dts/qcom/sc7180.dtsi
index d46b383..40d6a28 100644
--- a/arch/arm64/boot/dts/qcom/sc7180.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7180.dtsi
@@ -2,7 +2,7 @@
/*
* SC7180 SoC device tree source
*
- * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2019-20, The Linux Foundation. All rights
reserved.
*/
#include <dt-bindings/clock/qcom,dispcc-sc7180.h>
@@ -1885,6 +1885,7 @@
iommus = <&adreno_smmu 0>;
operating-points-v2 = <&gpu_opp_table>;
qcom,gmu = <&gmu>;
+ #cooling-cells = <2>;
Presumably we should add this to the devicetree bindings, too?
Yes, thanks for catching this. Will update in the next patch.
interconnects = <&gem_noc MASTER_GFX3D
&mc_virt SLAVE_EBI1>;
interconnect-names = "gfx-mem";
@@ -3825,16 +3826,16 @@
};
gpuss0-thermal {
- polling-delay-passive = <0>;
+ polling-delay-passive = <100>;
Why did you make this change? I'm pretty sure that we _don't_ want
this since we're using interrupts for the thermal sensor. See commit
22337b91022d ("arm64: dts: qcom: sc7180: Changed polling mode in
Thermal-zones node").
I was going to ask the same, this shouldn't be needed.
As per our understanding unlike "polling-delay", this delay property is
intended to activate polling thread on post trip threshold violation and
it is irrespective of sensor is capable for trip interrupt or not.
This polling is more of governor related. Below are the few references
from Documentation/code which tells polling-delay-passive is needed for
IPA for better IPA performance.
As per Power allocator documentations
1.
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/Documentation/driver-api/thermal/power_allocator.rst?h=v5.4.71#n264
"The power allocator governor's PID controller works best if there is a
periodic tick. If you have a driver that calls
`thermal_zone_device_update()` (or anything that ends up calling the
governor's `throttle()` function) repetitively, the governor response
won't be very good. Note that this is not particular to this
governor, step-wise will also misbehave if you call its throttle()
faster than the normal thermal framework tick (due to interrupts for
example) as it will overreact"
2. In Power allocator code, when switch_on/control trip temp violation,
it is enabling passive counter to activate passive polling @
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/thermal/power_allocator.c?h=v5.4.71#n634
3. while calculating derivative term, it is using passive_delay @
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/thermal/power_allocator.c?h=v5.4.71#n243
4. Sensor interrupt will work if temperature is fluctuating between
trip_temp and hysteresis. But say a case where we are not enabling
polling-delay-passive. In this case if current temperature >
control_temp trip(2nd passive trip) and
temperature trend is still raising, then sensor high trip will be
disabled (OR configured for critical trip threshold). No more trip
interrupt from sensor until it reaches critical trip or falls below
control_temp hysteresis.
How the governor re-evaluate its next mitigation without passive
polling thread here ?
I think the same is required for CPU thermal zone as well.
polling-delay = <0>;
thermal-sensors = <&tsens0 13>;
trips {
gpuss0_alert0: trip-point0 {
- temperature = <90000>;
+ temperature = <95000>;
hysteresis = <2000>;
- type = "hot";
+ type = "passive";
Matthias probably knows better, but I wonder if we should be making
two passive trip levels like we do with CPU. IIRC this is important
if someone wants to be able to use this with IPA.
Yes, please introduce a second trip point and make both of them
'passive'.
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Adding Manaf here.
-Akhil.
