Re: [PATCH 00/11] thermal: add new flag irq-mode for trip point

From: "Krzysztof Kozłowski" <k.kozlowski.k+lkml@gmail.com>
To: l.luba@partner.samsung.com
Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-pm@vger.kernel.org, rui.zhang@intel.com,
	edubezval@gmail.com, daniel.lezcano@linaro.org,
	robh+dt@kernel.org, mark.rutland@arm.com, corbet@lwn.net,
	"Bartłomiej Żołnierkiewicz" <b.zolnierkie@samsung.com>
Subject: Re: [PATCH 00/11] thermal: add new flag irq-mode for trip point
Date: Wed, 17 Oct 2018 09:03:13 +0200	[thread overview]
Message-ID: <CAJKOXPei6b7TnOnG7DUMNm+xEUsMxqcMOfbG10cJbrNROXLN2w@mail.gmail.com> (raw)
In-Reply-To: <20181016145637eucas1p2dfa78042b9fd4fd27af7cc8537b7f485~eHqCoEO-42133821338eucas1p2F@eucas1p2.samsung.com>

On Tue, 16 Oct 2018 at 16:56, Lukasz Luba <l.luba@partner.samsung.com> wrote:
>
> Hi all,
>
> This patch set adds new flag and mechanism in thermal trip point in DT.
> The current situation with 'passive' (passive cooling - DVFS)
> trip point is that it enables polling mode in thermal framework.

For DT platform, I checked it some months ago... and that time I was
pretty sure - passive mode does not enable polling (unless you tell it
explicitly with "polling-delay-passive"). Maybe something changed...
but quick look at the code tell me that not. Passive does not indicate
polling mode.

Why do you think that passive enables polling?

Best regards

> If the device supports irqs fired when the desired temerature is met,
> thermal framwork should be notifed from driver's irq routine.
> This is sufficent and there is no need of polling.
> As a workaround, people declare trip point as 'active'
> (active cooling, i.e. fan) to bypass polling mode setup in thermal
> framework.
>
> With this patch set trip point 'passive' declared in DT with explicit flag:
> 'irq-mode;' will not register itself as polling mode.
>
> A good example is Exynos4 SoC family, where there is 4 HW supported
> trip points and there is a need of 6. The rest 2 are declared as 'passive'
> without 'irq-mode;' flag, thus polling needed.
>
> It does not break existing design for trip points which do not have 'irq-mode'
> flag - they will use polling.
>
> For consistency this flag should be added to all trip point types('active',
> 'passive', 'hot', 'critical') when need (meaning, when irq will notify thermal
> framework).
>
> Regards,
> Lukasz Luba
>
> Lukasz Luba (11):
>   thermal: remove unused function parameter
>   thermal: add irq-mode configuration for trip point
>   thermal: add new sysfs file for irq-mode
>   Doc: thermal: new irq-mode for trip point
>   Doc: DT: thermal: new irq-mode for trip point
>   DT: arm64: exynos: add support for thermal trip irq-mode
>   DT: arm64: exynos7: add support for thermal trip irq-mode
>   DT: arm: exynos4: add support for thermal trip irq-mode
>   DT: arm: exynos: add support for thermal trip irq-mode
>   DT: arm: exynos: add support for thermal trip irq-mode
>   DT: arm: exynos: add support for thermal trip irq-mode
>
>  .../devicetree/bindings/thermal/thermal.txt        |   7 ++
>  Documentation/thermal/sysfs-api.txt                |   9 ++
>  arch/arm/boot/dts/exynos4-cpu-thermal.dtsi         |  10 +-
>  arch/arm/boot/dts/exynos5410-odroidxu.dts          |  10 +-
>  arch/arm/boot/dts/exynos5420-trip-points.dtsi      |  10 +-
>  arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi |  40 +++++---
>  arch/arm64/boot/dts/exynos/exynos5433-tmu.dtsi     | 105 ++++++++++++++-------
>  .../arm64/boot/dts/exynos/exynos7-trip-points.dtsi |   8 ++
>  drivers/thermal/of-thermal.c                       |  17 ++++
>  drivers/thermal/thermal_core.c                     |  16 ++--
>  drivers/thermal/thermal_sysfs.c                    |  53 ++++++++++-
>  include/linux/thermal.h                            |   5 +
>  12 files changed, 226 insertions(+), 64 deletions(-)
>
> --
> 2.7.4
>