| Message ID | 20200604015317.31389-1-thara.gopinath@linaro.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Introduce Power domain based warming device driver | expand |
Hi! > Certain resources modeled as a generic power domain in linux kernel can be > used to warm up the SoC (mx power domain on sdm845) if the temperature > falls below certain threshold. These power domains can be considered as > thermal warming devices. (opposite of thermal cooling devices). Would you explain when this is needed? I'd normally expect "too low" temperature to be a problem during power-on, but at that time Linux is not running so it can not provide the heating... Best regards, Pavel
On 6/16/20 6:53 AM, Pavel Machek wrote: > Hi! > >> Certain resources modeled as a generic power domain in linux kernel can be >> used to warm up the SoC (mx power domain on sdm845) if the temperature >> falls below certain threshold. These power domains can be considered as >> thermal warming devices. (opposite of thermal cooling devices). > > Would you explain when this is needed? > > I'd normally expect "too low" temperature to be a problem during power-on, but at > that time Linux is not running so it can not provide the heating... Hi Pavel, This is more in the scenario if the system in on and temperature is dipping (I have been told in colder climates). Idea is to turn on resources so as to prevent further dipping of temperature if possible. > > Best regards, > > Pavel >
Hi! > >>falls below certain threshold. These power domains can be considered as > >>thermal warming devices. (opposite of thermal cooling devices). > > > >Would you explain when this is needed? > > > >I'd normally expect "too low" temperature to be a problem during power-on, but at > >that time Linux is not running so it can not provide the heating... > Hi Pavel, > > This is more in the scenario if the system in on and temperature is dipping > (I have been told in colder climates). Idea is to turn on resources so as to > prevent further dipping of temperature if possible. I guess even that makes sense... But, out of curiosity, do you know which kind of device is that and in what kind of environment? I mean, theoretically it may make sense on a cellphone, but... I guess you have some fun device and would like to know what it is :-). Hmm. And we can make this quite generic. while (too_cold()) barrier(); Wasting power is really easy :-). Pavel
Certain resources modeled as a generic power domain in linux kernel can be used to warm up the SoC (mx power domain on sdm845) if the temperature falls below certain threshold. These power domains can be considered as thermal warming devices. (opposite of thermal cooling devices). In kernel, these warming devices can be modeled as a thermal cooling device. Since linux kernel today has no instance of a resource modeled as a power domain acting as a thermal warming device, a generic power domain based thermal warming device driver that can be used pan-Socs is the approach taken in this patch series. Since thermal warming devices can be thought of as the mirror opposite of thermal cooling devices, this patch series re-uses thermal cooling device framework. To use these power domains as warming devices require further tweaks in the thermal framework which are out of scope of this patch series. These tweaks have been posted as a separate series[1]. The first patch in this series extends the genpd framework to export out the performance states of a power domain so that when a power domain is modeled as a cooling device, the number of possible states and current state of the cooling device can be retrieved from the genpd framework. The second patch implements the newly added genpd callback for Qualcomm RPMH power domain driver which hosts the mx power domain. The third patch introduces a new cooling device register API that allows a parent to be specified for the cooling device. The fourth patch introduces the generic power domain warming device driver. The fifth patch extends Qualcomm RPMh power controller driver to register mx power domain as a thermal warming device in the kernel. The sixth patch describes the dt binding extensions for mx power domain to be a thermal warming device. The seventh patch introduces the DT entreis for sdm845 to register mx power domain as a thermal warming device. v1->v2: - Rename the patch series from "qcom: Model RPMH power domains as thermal cooling devices" to "Introduce Power domain based thermal warming devices" as it is more appropriate. - Introduce a new patch(patch 3) describing the dt-bindings for generic power domain warming device. - Patch specific changes mentioned in respective patches. v2->v3: - Changed power domain warming device from a virtual device node entry in DT to being a subnode of power domain controller binding following Rob's review comments. - Implemented Ulf's review comments. - The changes above introduced two new patches (patch 3 and 4) v3->v4: - Dropped late_init hook in cooling device ops. Instead introduced a new cooling device register API that allows to define a parent for the cooling device. - Patch specific changes mentioned in respective patches. v4->v5: - Dropped the patch that introduced the cooling device register API with parent as per review comments from Ulf. - Patch specific changes mentioned in respective patches. v5->v6: - Rebased to latest kernel - Few other fixes identified in the review process mentioned in respective patches 1. https://lkml.org/lkml/2019/9/18/1180 Thara Gopinath (6): PM/Domains: Add support for retrieving genpd performance states information soc: qcom: rpmhpd: Introduce function to retrieve power domain performance state count thermal: Add generic power domain warming device driver. soc: qcom: Extend RPMh power controller driver to register warming devices. dt-bindings: power: Extend RPMh power controller binding to describe thermal warming device arm64: dts: qcom: Indicate rpmhpd hosts a power domain that can be used as a warming device. .../devicetree/bindings/power/qcom,rpmpd.yaml | 3 + arch/arm64/boot/dts/qcom/sdm845.dtsi | 1 + drivers/base/power/domain.c | 37 ++++ drivers/soc/qcom/rpmhpd.c | 25 ++- drivers/thermal/Kconfig | 10 ++ drivers/thermal/Makefile | 4 + drivers/thermal/pd_warming.c | 169 ++++++++++++++++++ include/linux/pd_warming.h | 29 +++ include/linux/pm_domain.h | 13 ++ 9 files changed, 290 insertions(+), 1 deletion(-) create mode 100644 drivers/thermal/pd_warming.c create mode 100644 include/linux/pd_warming.h