Re: [RFC PATCH 0/2] thermal: Add generic devfreq cooling device

[Punit Agrawal <punit.agrawal@arm.com>]

Hi Chanwoo,

Chanwoo Choi <cw00.choi@samsung.com> writes:

> This patchset introduce the generic devfreq cooling device for generic thermal
> framework. The devfreq devices are used ad cooling device to reduce the
> overheating temperature. This patch is based on drivers/thermal/cpu_cooling.c.
> The devfreq cooling device can change the ragne of the frequency table of
> devfreq device according to cooling level in device tree file.
>

Have you had a look at the devfreq cooling patches from Javi[0][1]? How
is the current patchset different?

At first glance, it seems that you are not implementing the extensions
that allow devfreq cooling devices to be used with power_allocator
thermal governor that got merged in v4.2-rc1.

Thanks,
Punit

[0] http://article.gmane.org/gmane.linux.power-management.general/61936
[1] http://article.gmane.org/gmane.linux.power-management.general/62417


> To verify the devfreq cooling device driver, I testd it with following platform:
>
> For example,
> - The Mali GPU of Exynos5433 SoC uses the devfreq framework to support the DVFS
> feature and Exynos5433 contains the G3D (GPU) thermal sensor. Following example
> explain the correlation between mali dt node and thermal sensor/zone.
> : thermal sensor : G3D sensor of Samsung Exynos5433 [1][2]
> : devfreq cooling device : Mali GPU [3]
>
> According to the temperature of g3d thermal sensor inclued in Exynos5433,
> devfreq cooling device can change the maximum frequency of Mali GPU.
>
> 1. In Exynos5433-based board dts file, Mali GPU dt node uses the devfreq
> framework to suppot the DVFS feature. Following dt node includes the
> both 'cooling-cells' and 'operating-points' which means the supported
> frequency entries:
>
> 	mali: mali@14AC0000 {
> 		compatible = "arm,mali-midgard";
> 		reg = <0x14AC0000 0x5000>;
> 		interrupts = <0 282 0>, <0 283 0>, <0 281 0>;
> 		interrupt-names = "JOB", "MMU", "GPU";
> 		clocks = <&cmu_g3d CLK_ACLK_G3D>;
> 		clock-names = "clk_mali";
> 		power-domains = <&pd_g3d>;
> 		status = "disabled";
>
> 		#cooling-cells = <2>;
>
> 		operating-points = <
> 			700000 1150000
> 			600000 1150000
> 			550000 1125000
> 			500000 1075000
> 			420000 1025000
> 			350000 1025000
> 			266000 1000000
> 			160000 1000000
> 		>;
> 	};
>
> 2. In exynos5433.dtsi, G3D thermal sensor measure the temperature of Mali GPU:
>
> 	tmu_g3d: tmu@10070000 {
> 		compatible = "samsung,exynos5433-tmu";
> 		reg = <0x10070000 0x200>;
> 		interrupts = <0 99 0>;
> 		clocks = <&cmu_peris CLK_PCLK_TMU1_APBIF>,
> 			 <&cmu_peris CLK_SCLK_TMU1>;
> 		clock-names = "tmu_apbif", "tmu_sclk";
> 		#include "exynos5433-tmu-sensor-conf.dtsi"
> 		status = "disabled";
> 	};
>
> 3. In exynos5433-tmu.dtsi, thermal-zones includes both trip points and
> cooling-maps of g3d thermal sensor. Following cooling-maps show the match
> between each trip point and each cooling device (devfreq device of mali):
>
> 	thermal-zones {
> 		/* ...... */
> 		g3d_thermal: g3d-thermal {
> 			thermal-sensors = <&tmu_g3d>;
> 			polling-delay-passive = <0>;
> 			polling-delay = <0>;
> 			trips {
> 				g3d_alert_0: g3d-alert-0 {
> 					temperature = <30000>;	/* millicelsius */
> 					hysteresis = <10000>;	/* millicelsius */
> 					type = "active";
> 				};
> 				g3d_alert_1: g3d-alert-1 {
> 					temperature = <40000>;	/* millicelsius */
> 					hysteresis = <10000>;	/* millicelsius */
> 					type = "active";
> 				};
>
> 				/* ...... */
> 			};
>
> 			cooling-maps {
> 				map0 {
> 					/* Set maximum frequency as 550MHz  */
> 					trip = <&g3d_alert_0>;
> 					cooling-device = <&mali 2 2>;
> 				};
> 				map1 {
> 					/* Set maximum frequency as 420MHz  */
> 					trip = <&g3d_alert_1>;
> 					cooling-device = <&mali 4 4>;
> 				};
>
> 				/* ...... */
> 			};
> 		};
>
> 		......
> 	};
>
> [1] https://git.kernel.org/cgit/linux/kernel/git/kgene/linux-samsung.git/commit/?h=v4.3-next/dt64-samsung&id=ac008f6b537703bb9a6fcc3882ca4af3331aa24f
> [2] https://git.kernel.org/cgit/linux/kernel/git/kgene/linux-samsung.git/commit/?h=v4.3-next/dt64-samsung&id=bcddc3a84e49ca1c646cf2081687a544a15f9218
> [3] malideveloper.arm.com/downloads/drivers/TX041/r5p0-06rel0/TX041-SW-99002-r5p0-06rel0.tgz
>
> Chanwoo Choi (2):
>   PM: devfreq: Add the prototype of update_devfreq() to export
>   thermal: devfreq_cooling: Add generic devfreq cooling device implementaion
>
>  .../devicetree/bindings/thermal/thermal.txt        |   8 +-
>  drivers/devfreq/devfreq.c                          |  22 +-
>  drivers/thermal/Kconfig                            |  11 +
>  drivers/thermal/Makefile                           |   3 +
>  drivers/thermal/devfreq-cooling.c                  | 309 +++++++++++++++++++++
>  include/linux/devfreq-cooling.h                    |  80 ++++++
>  include/linux/devfreq.h                            |   7 +
>  7 files changed, 425 insertions(+), 15 deletions(-)
>  create mode 100644 drivers/thermal/devfreq-cooling.c
>  create mode 100644 include/linux/devfreq-cooling.h