linux-kernel - Re: [RFC PATCH v3 0/7] PM / devfreq: Simple QoS for exynos-bus using interconnect

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Date:   Sun, 22 Dec 2019 04:58:38 +0900
From:   Chanwoo Choi <chanwoo@...nel.org>
To:     Artur Świgoń <a.swigon@...sung.com>
Cc:     devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>, inki.dae@...sung.com,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        Leonard Crestez <leonard.crestez@....com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>
Subject: Re: [RFC PATCH v3 0/7] PM / devfreq: Simple QoS for exynos-bus using interconnect

Hi Artur,

I agree this approach. On next version, please update exynos-bus
dt-binding document with example.

On Fri, Dec 20, 2019 at 9:01 PM Artur Świgoń <a.swigon@...sung.com> wrote:
>
> The following patchset adds interconnect[1][2] framework support to the
> exynos-bus devfreq driver. Extending the devfreq driver with
> interconnect functionality started as a response to the issue referenced
> in [3]. The patches can be subdivided into three groups:
>
> (a) Tweaking the interconnect framework to support the exynos-bus use
> case (patches 01--03/07). Exporting of_icc_get_from_provider() allows to
> avoid hardcoding every single graph edge in the DT or driver source, and
> relaxing the requirement on #interconnect-cells removes the need to
> provide dummy node IDs in the DT. A new field in struct icc_provider is
> used to explicitly allow configuring node pairs from two different
> providers.
>
> (b) Implementing interconnect providers in the exynos-bus devfreq driver
> and adding required DT properties for one selected platform, namely
> Exynos4412 (patches 04--05/07). Due to the fact that this aims to be a
> generic driver for various Exynos SoCs, node IDs are generated
> dynamically (rather than hardcoded).
>
> (c) Implementing a sample interconnect consumer for exynos-mixer
> targeted at solving the issue referenced in [3], again with DT
> properties only for Exynos4412 (patches 06--07/07).
>
> Integration of devfreq and interconnect frameworks is achieved by using
> the dev_pm_qos_*() API. When CONFIG_INTERCONNECT is 'n' (such as in
> exynos_defconfig) all interconnect API functions are no-ops.
>
> This series depends on these three patches (merged into devfreq-next[6]):
> * https://patchwork.kernel.org/patch/11279087/
> * https://patchwork.kernel.org/patch/11279093/
> * https://patchwork.kernel.org/patch/11293765/
> and on this series:
> * https://patchwork.kernel.org/cover/11304545/
> (which does not apply cleanly on next-20191220, adding
> --exclude=arch/arm/boot/dts/exynos5422-odroid-core.dtsi to 'git am' is a
> quick workaround)
>
> ---
> Changes since v2 [5]:
> * Use icc_std_aggregate().
> * Implement a different modification of apply_constraints() in
>   drivers/interconnect/core.c (patch 03).
> * Use 'exynos,interconnect-parent-node' in the DT instead of
>   'devfreq'/'parent', depending on the bus.
> * Rebase on DT patches that deprecate the 'devfreq' DT property.
> * Improve error handling, including freeing generated IDs on failure.
> * Remove exynos_bus_icc_connect() and add exynos_bus_icc_get_parent().
>
> ---
> Changes since v1 [4]:
> * Rebase on coupled regulators patches.
> * Use dev_pm_qos_*() API instead of overriding frequency in
>   exynos_bus_target().
> * Use IDR for node ID allocation.
> * Reverse order of multiplication and division in
>   mixer_set_memory_bandwidth() (patch 07) to avoid integer overflow.
>
> ---
> Artur Świgoń
> Samsung R&D Institute Poland
> Samsung Electronics
>
> ---
> References:
> [1] Documentation/interconnect/interconnect.rst
> [2] Documentation/devicetree/bindings/interconnect/interconnect.txt
> [3] https://patchwork.kernel.org/patch/10861757/ (original issue)
> [4] https://patchwork.kernel.org/cover/11054417/ (v1 of this RFC)
> [5] https://patchwork.kernel.org/cover/11152595/ (v2 of this RFC)
> [6] https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-next
>
> Artur Świgoń (6):
>   interconnect: Export of_icc_get_from_provider()
>   interconnect: Relax requirement in of_icc_get_from_provider()
>   interconnect: Allow inter-provider pairs to be configured
>   arm: dts: exynos: Add interconnect bindings for Exynos4412
>   devfreq: exynos-bus: Add interconnect functionality to exynos-bus
>   arm: dts: exynos: Add interconnects to Exynos4412 mixer
>
> Marek Szyprowski (1):
>   drm: exynos: mixer: Add interconnect support
>
>  .../boot/dts/exynos4412-odroid-common.dtsi    |   5 +
>  arch/arm/boot/dts/exynos4412.dtsi             |   1 +
>  drivers/devfreq/exynos-bus.c                  | 144 ++++++++++++++++++
>  drivers/gpu/drm/exynos/exynos_mixer.c         |  71 ++++++++-
>  drivers/interconnect/core.c                   |  16 +-
>  include/linux/interconnect-provider.h         |   8 +
>  6 files changed, 232 insertions(+), 13 deletions(-)
>
> --
> 2.17.1
>


-- 
Best Regards,
Chanwoo Choi