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Subject: Re: [PATCH v8 0/7] Exynos: Simple QoS for exynos-bus using
 interconnect
To:     Sylwester Nawrocki <s.nawrocki@samsung.com>,
        georgi.djakov@linaro.org, krzk@kernel.org
Cc:     devicetree@vger.kernel.org, robh+dt@kernel.org,
        a.swigon@samsung.com, myungjoo.ham@samsung.com,
        inki.dae@samsung.com, sw0312.kim@samsung.com,
        b.zolnierkie@samsung.com, m.szyprowski@samsung.com,
        linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
        linux-samsung-soc@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org
From:   Chanwoo Choi <cw00.choi@samsung.com>
Organization: Samsung Electronics
Message-ID: <25228d5e-4bc3-2e61-6bd5-43e66ae82244@samsung.com>
Date:   Thu, 5 Nov 2020 11:20:55 +0900
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        <20201104103657.18007-1-s.nawrocki@samsung.com>
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Hi Sylwester,

On 11/4/20 7:36 PM, Sylwester Nawrocki wrote:
> This patchset adds interconnect API support for the Exynos SoC "samsung,
> exynos-bus" compatible devices, which already have their corresponding
> exynos-bus driver in the devfreq subsystem.  Complementing the devfreq
> driver with an interconnect functionality allows to ensure the QoS
> requirements of devices accessing the system memory (e.g. video processing
> devices) are fulfilled and aallows to avoid issues like the one discussed
> in thread [1].
> 
> This patch series adds implementation of the interconnect provider per each
> "samsung,exynos-bus" compatible DT node, with one interconnect node per
> provider.  The interconnect code which was previously added as a part of
> the devfreq driver has been converted to a separate platform driver.
> In the devfreq a corresponding virtual child platform device is registered.
> Integration of devfreq and interconnect frameworks is achieved through
> the PM QoS API.
> 
> A sample interconnect consumer for exynos-mixer is added in patches 6/7,
> 7/7, it is currently added only for exynos4412 and allows to address the
> mixer DMA underrun error issues [1].
> 
> Changes since v7:
>  - drivers/interconnect/exynos renamed to drivers/interconnect/samsung,
>  - added INTERCONNECT_SAMSUNG Kconfig symbol,
>  - added missing driver sync_state callback,
>  - improved the DT binding description,
>  - added a patch adding maintainers entry,
>  - updated comment in patch 7/7, typo fix (patch 1/7).
> 
> The series has been tested on Odroid U3 board. It is based on v5.10-rc1.
> 
> --
> Regards,
> Sylwester
> 
> Changes since v6:
>  - the interconnect consumer DT bindings are now used to describe dependencies
>    of the interconnects (samsung,exynos-bus nodes),
>  - bus-width property replaced with samsung,data-clk-ratio,
>  - adaptation to recent changes in the interconnect code
>    (of_icc_get_from_provider(), icc_node_add()).
> 
> Changes since v5:
>  - addition of "bus-width: DT property, which specifies data width
>    of the interconnect bus (patches 1...2/6),
>  - addition of synchronization of the interconnect bandwidth setting
>    with VSYNC (patch 6/6).
> 
> Changes since v3 [4] (v4 skipped to align with patchset [1]), detailed
> changes are listed in patches:
>  - conversion to a separate interconnect (platform) driver,
>  - an update of the DT binding documenting new optional properties:
>    #interconnect-cells, samsung,interconnect-parent in "samsung,exynos-bus"
>    nodes,
>  - new DT properties added to the SoC, rather than to the board specific
>    files.
> 
> 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 [6]:
>  - 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.
> 
> 
> References:
> [1] https://patchwork.kernel.org/patch/10861757/ (original issue)
> [2] https://www.spinics.net/lists/linux-samsung-soc/msg70014.html
> [3] https://www.spinics.net/lists/arm-kernel/msg810722.html
> [4] https://lore.kernel.org/linux-pm/20191220115653.6487-1-a.swigon@samsung.com
> [5] https://patchwork.kernel.org/cover/11054417/ (v1 of this RFC)
> [6] https://patchwork.kernel.org/cover/11152595/ (v2 of this RFC)
> 
> 
> Artur Świgoń (1):
>   ARM: dts: exynos: Add interconnects to Exynos4412 mixer
> 
> Sylwester Nawrocki (6):
>   dt-bindings: devfreq: Add documentation for the interconnect
>     properties
>   interconnect: Add generic interconnect driver for Exynos SoCs
>   MAINTAINERS: Add entry for Samsung interconnect drivers
>   PM / devfreq: exynos-bus: Add registration of interconnect child
>     device
>   ARM: dts: exynos: Add interconnect properties to Exynos4412 bus nodes
>   drm: exynos: mixer: Add interconnect support
> 
>  .../devicetree/bindings/devfreq/exynos-bus.txt     |  71 +++++++-
>  MAINTAINERS                                        |   7 +
>  arch/arm/boot/dts/exynos4412.dtsi                  |   7 +
>  drivers/devfreq/exynos-bus.c                       |  17 ++
>  drivers/gpu/drm/exynos/exynos_mixer.c              | 146 ++++++++++++++-
>  drivers/interconnect/Kconfig                       |   1 +
>  drivers/interconnect/Makefile                      |   1 +
>  drivers/interconnect/samsung/Kconfig               |  13 ++
>  drivers/interconnect/samsung/Makefile              |   4 +
>  drivers/interconnect/samsung/exynos.c              | 199 +++++++++++++++++++++
>  10 files changed, 456 insertions(+), 10 deletions(-)
>  create mode 100644 drivers/interconnect/samsung/Kconfig
>  create mode 100644 drivers/interconnect/samsung/Makefile
>  create mode 100644 drivers/interconnect/samsung/exynos.c
> 

I tested it. It is well working. Thanks.

Tested-by: Chanwoo Choi <cw00.choi@samsung.com>


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics